Before performing TPLO surgery, the veterinary surgeon selects the appropriate bone plate from a range of sizes specific to the implant system being used.

The plate size chart is the reference tool that guides this selection.

Choosing the correct plate is as important as the surgical technique itself an undersized plate risks mechanical failure, and an oversized plate may not fit the tibial anatomy correctly.

Quick answer: The TPLO plate size chart matches body weight and tibial bone dimensions to the appropriate implant. Arthrex plates range from 2.0 mm to 4.5 mm; Synthes covers a similar range. Tibial width is measured on preoperative radiographs and used alongside body weight to select the plate and screw configuration.

Key takeaways

• The plate size chart is a preoperative planning tool that matches body weight and bone dimensions to the appropriate implant
• Arthrex offers TPLO plates from 2.0 mm to 4.5 mm: the small sizes are purpose-designed for small breed anatomy, not scaled-down large plates
• Tibial width is measured on preoperative radiographs: a primary determinant of plate selection alongside body weight
• Plate selection is system-specific: Arthrex plates require Arthrex instruments and screws; Synthes requires Synthes-specific tools
• The plate is single-use sterile: a new plate must be available if a different size is needed intraoperatively
• Correct plate selection directly affects outcomes: undersized plates risk fatigue fracture; oversized plates cause soft tissue irritation

What the plate size chart does

The TPLO plate size chart is a lookup reference similar in function to the rotation chart and weight chart that are part of the Arthrex and Synthes TPLO planning systems.

It takes known inputs (primarily body weight and tibial dimensions measured on radiographs) and outputs the recommended plate size from the manufacturer's product range.

SustainableVet.org explains: a TPLO plate size chart is a reference guide used by veterinary surgeons to select the appropriate implant size for stabilizing the tibia after TPLO surgery.

Plates come in various lengths and hole numbers to fit different dog breeds and bone sizes.

The chart removes the guesswork from a decision that significantly affects the mechanical performance of the repair.

A plate that is correctly sized distributes load evenly across all screw holes and lies flush against the cortical bone surface, minimizing stress risers and soft tissue irritation.

Key variables in plate size selection

Body weight

Body weight is the primary initial filter. Heavier dogs generate higher joint forces and require larger, stiffer plates to withstand the loads applied during weight-bearing and normal activity.

General size categories used across Arthrex and Synthes product lines:

• Small breed (under 10 to 15 kg): 2.0 mm or 2.4 mm plates
• Medium breed (15 to 30 kg): 3.5 mm plates
• Large breed (30 to 50 kg): 3.5 mm or 4.5 mm plates
• Giant breed (over 50 kg): 4.5 mm plates; locking systems particularly important

These ranges are approximate and surgeon-dependent. The specific manufacturer chart values take precedence over general categories.

Tibial width and bone dimensions

The plate must span the osteotomy site with at least 2 screws proximal and 2 screws distal to the cut for adequate fixation.

The tibial width at the planned osteotomy level measured in millimeters on a mediolateral radiograph determines which plate length and screw configuration provides sufficient purchase without overhanging the bone margins.

Number of screw holes

Plates are available with different numbers of holes (typically 4, 5, or 6 holes for standard sizes).

More holes provide more screw fixation points, which is important in larger dogs or those expected to be highly active during recovery.

SustainableVet.org notes: plates come in various lengths and hole numbers to fit different dog breeds and bone sizes, allowing surgeons to select the configuration that best matches each individual patient's anatomy.

Arthrex TPLO plate system

Arthrex produces the most widely used TPLO locking plate system in the United States. The Arthrex TPLO Locking Plate System is designed with specific anatomical features to facilitate consistent plate placement.

From Arthrex Vet Systems documentation: the 2.0 mm and 2.4 mm TPLO locking plates are not simply shrunken versions of larger TPLO plates.

The smaller plates were purpose-designed for small breed bone anatomy.

Small dogs have proportionally different tibial geometry, and scaling down a large plate does not optimize screw angle or load distribution.

Arthrex's 4.5 mm plate incorporates a caudal tilt designed for improved screw purchase in the proximal tibial segment, with a proximal screw trajectory directed to avoid the osteotomy line.

This is an important design feature: screws that inadvertently cross the osteotomy reduce fixation quality and risk creating a stress concentration at the cut.

The Arthrex system includes an InternalBrace ligament augmentation option for dogs with severe stifle instability. This knotless lateral stabilization technique is not part of standard TPLO.

For the Arthrex plate overview, see Arthrex TPLO plate overview and use. For the Synthes plate overview, see Synthes TPLO plate overview and use.

How the plate size chart integrates with other planning tools

The plate size chart is used in concert with two other charts in the preoperative planning sequence:

Rotation chart: determines how many degrees the tibial segment must be rotated to achieve the target postoperative TPA of approximately 5 degrees. This is completed using the preoperative TPA measurement from radiographs.

Weight chart: guides post-operative weight-bearing expectations during rehabilitation.

All three charts together form the complete preoperative planning and post-operative monitoring framework. For the rotation chart, see Arthrex TPLO rotation chart explained.

For the weight chart, see Arthrex TPLO weight chart explained.

Why correct plate size matters

Mechanical adequacy: the plate must be strong enough to withstand the bending forces applied across the osteotomy during recovery typically equivalent to body weight or more during brief dynamic loading events (jumping down from a bed despite restrictions). An undersized plate risks fatigue fracture if the osteotomy takes longer to heal than expected.

Biological fit: the plate must lie flush against the bone surface. A plate that sits proud causes soft tissue irritation and can lead to the implant-associated pain and lameness that eventually requires plate removal.

Screw purchase quality: screws that are too short for the bone depth, or too long and penetrating the far cortex inappropriately, compromise fixation quality. Plate size selection is linked to the specific screw lengths that are compatible with each plate variant.

Frequently asked questions

Can the surgeon change the plate size during surgery?

Yes. If the preoperatively planned plate size does not fit correctly once the osteotomy is made and the bone is positioned, the surgeon may open a different plate size.

This is why surgical teams keep a range of plate sizes available in the sterile field or immediately accessible.

The plate is a single-use sterile item it cannot be resterilized if opened and unused.

Are Arthrex and Synthes plates interchangeable?

No. Each manufacturer's plates require that manufacturer's specific screws, instruments, and jigs.

Using Synthes screws in an Arthrex plate (or vice versa) risks stripped screw heads, incorrect screw purchase geometry, and compromised fixation. The systems are entirely separate.

How does the surgeon know which plate to order before surgery?

The surgeon measures the tibial width and records body weight at the preoperative planning appointment.

Based on these measurements and the manufacturer's size chart, a specific plate and screw set is ordered or identified from the implant inventory before surgery.

Is a larger plate always better for a big dog?

Not necessarily.

The plate must fit the tibial anatomy. A plate longer than the available cortical surface overhangs the bone, creating soft tissue irritation and stress concentration at the plate ends.

The goal is the smallest plate that provides adequate mechanical fixation for the dog's body weight and expected activity level.

What happens if the wrong plate size is used?

An undersized plate risks fatigue fracture under repetitive loading. An oversized plate may not conform to the bone surface, reducing screw fixation quality and potentially causing soft tissue irritation.

Plate failure or malposition requiring revision is a recognized complication of poor implant selection.

Resources

• Arthrex Vet Systems. TPLO Locking Plate System. arthrexvetsystems.com
• Arthrex Vet Systems. 4.5 mm TPLO Plates and Screws. arthrexvetsystems.com
• PMC. Influence of Fixation Systems on Complications After TPLO in Dogs Greater Than 45 kg. ncbi.nlm.nih.gov
• VCA Animal Hospitals. Tibial Plateau Leveling Osteotomy (TPLO) in Dogs. vcahospitals.com

If your dog has been diagnosed with a torn cranial cruciate ligament, you have likely encountered the acronym TPLO possibly before you knew what it meant or why it was being recommended.

TPLO is the most commonly performed CCL surgery in the US. Understanding what the acronym means helps demystify why the surgery works the way it does.

Quick answer: TPLO stands for Tibial Plateau Leveling Osteotomy: Tibial (shin bone), Plateau (upper surface forming the knee), Leveling (making the plateau closer to horizontal), Osteotomy (controlled bone cut). The surgery stabilizes the knee by rotating the tibia, making the CCL biomechanically unnecessary.

Key takeaways

• T = Tibial: the tibia, the shin bone below the knee (stifle) joint
• P = Plateau: the upper tibial surface forming the knee joint; in dogs it has a significant slope called the tibial plateau angle
• L = Leveling: reducing the tibial plateau angle to closer to parallel with the ground, changing joint biomechanics
• O = Osteotomy: a controlled surgical bone cut that allows the tibial segment to be repositioned and fixed
• TPLO does not repair the torn CCL: it changes joint geometry so the ligament becomes biomechanically unnecessary
• TPLO was first described in the early 1980s by Dr. Barclay Slocum and is now the most reliable procedure for CCL disease in dogs

Breaking down each word

T Tibial

The tibia is the main weight-bearing bone of the lower leg, running from the knee (stifle) joint to the ankle (tarsus).

In dogs, the tibia is not perfectly vertical it angles slightly forward relative to the femur above it. This angle contributes to the mechanical forces that act on the stifle during weight-bearing.

Veterinary Partner (VIN) explains: tibial refers to the shin bone.

P Plateau

The tibial plateau is the upper, relatively flat surface of the tibia that contacts the bottom of the femur to form the stifle joint.

Unlike in humans, where the tibial plateau is nearly horizontal, in dogs it has a significant slope the tibial plateau angle (TPA).

A steeper TPA creates more cranial tibial thrust during weight-bearing, which is the force that normally the CCL resists.

Veterinary Partner (VIN) defines it as: the upper surface of the shin bone; the bottom of the knee joint.

L Leveling

Leveling refers to the goal of the surgery: reducing the tibial plateau angle to approximately 5 degrees, making it closer to parallel with the ground.

When the tibial plateau is leveled, the femur no longer tends to slide forward relative to the tibia during weight-bearing the cranial tibial thrust is neutralized.

This is why a functioning CCL is no longer required after TPLO.

Veterinary Partner (VIN) defines it as: making the plateau more parallel to the ground.

O Osteotomy

An osteotomy is a controlled surgical cut through a bone a deliberate, planned fracture performed under anesthesia to allow repositioning of a bone segment.

TPLO involves a curved osteotomy through the proximal tibia, creating a segment that is rotated to the new angle and fixed with a bone plate and screws during healing.

Veterinary Partner (VIN) defines it as: a bone-cutting procedure like a controlled fracture of the bone.

Why TPLO was developed

Before TPLO, the dominant approach to CCL repair was extracapsular stabilization placing sutures outside the joint to mimic the CCL's function.

While effective in small dogs, this approach was unreliable in large, active dogs because the suture material eventually stretched or failed, and the joint depended on periarticular scar tissue for long-term stability.

Veterinary Specialty Center explains: TPLO changes the biomechanics of the knee so the joint can remain stable without relying on the damaged CCL.

Instead of replacing the torn ligament, it changes the mechanics of the knee entirely.

DVM360 confirms: TPLO alters the mechanical forces acting on the stifle, rendering the cranial cruciate ligament unnecessary.

Dr. Barclay Slocum first described TPLO in the early 1980s.

Veterinary Partner (VIN) notes that much research has been done since to refine the technique, and it has emerged as the most reliable technique for CCL disease management in dogs.

How TPLO differs from human ACL surgery

This is one of the most common points of confusion for owners.

In humans, ACL surgery typically involves replacing the torn ligament with a graft (taken from the patient's hamstring, patellar tendon, or a donor).

The new ligament is reconstructed to restore normal joint function.

TPLO does not reconstruct the CCL. It bypasses the need for a functioning CCL entirely by changing joint geometry.

Veterinary Specialty Center confirms: in people, ACL surgery replaces the torn ligament; in dogs, TPLO changes knee mechanics so the joint functions without the CCL.

This is why dogs cannot "re-tear" their CCL after TPLO there is no ligament replacement to fail. The stability provided by TPLO is structural and permanent.

What TPLO treats and who it is for

TPLO is used to treat cranial cruciate ligament (CCL) rupture the canine equivalent of the human ACL.

CCL rupture is the most common cause of hind limb lameness in dogs and costs US dog owners over $1 billion annually.

The ACVS recommends TPLO as the most commonly performed procedure for dogs over 60 lbs. It is also recommended for smaller dogs where long-term mechanical stability and minimal arthritis progression are priorities.

For the surgical causes guide, see what causes TPLO surgery to be needed in dogs. For the full surgical overview, see what is TPLO surgery in dogs?.

For the pros and cons of the procedure, see TPLO surgery pros and cons for dogs.

Frequently asked questions

Does TPLO stand for the same thing in all dogs?

Yes. The acronym and the procedure are the same regardless of breed, size, or the specific implant system used (Arthrex or Synthes).

The variation between cases is in the amount of tibial rotation required (based on the individual TPA), the plate size selected, and the post-operative protocol.

Is TPLO the same as TTA?

No. TTA (Tibial Tuberosity Advancement) is a different procedure with a similar goal both change knee biomechanics rather than replacing the CCL.

TTA advances the tibial tuberosity cranially rather than rotating the tibial plateau. They achieve knee stabilization through different geometric approaches.

Why is it called leveling if the bone is rotated?

The rotation of the tibial bone segment achieves the leveling.

When the proximal tibial segment is rotated, the angle of the tibial plateau changes it becomes less sloped, i.e., more level relative to the ground.

The procedure is named for the result (leveling) rather than the method (rotation).

Was TPLO invented for dogs?

Yes. TPLO was developed specifically for veterinary use in dogs in the early 1980s by Dr. Barclay Slocum.

It was developed because the canine stifle's anatomy and biomechanics differ significantly from the human knee particularly the steep tibial plateau angle that is uniquely problematic in dogs.

Why is TPLO preferred over other CCL surgeries for large dogs?

Large, active dogs generate higher joint forces than small dogs.

Extracapsular repair (lateral suture) provides stability through scar tissue formation adequate for small dogs but inadequate for the forces generated by large, active breeds.

TPLO provides bone-based mechanical stability that is not dependent on scar tissue, making it more durable and reliable for larger patients.

Resources

• Veterinary Partner (VIN). TPLO Surgery. veterinarypartner.vin.com
• VCA Animal Hospitals. Tibial Plateau Leveling Osteotomy (TPLO). vcahospitals.com
• DVM360. Understanding Tibial Plateau Leveling Osteotomies in Dogs. dvm360.com
• Veterinary Specialty Center. TPLO Surgery for Dogs. vetspecialty.com
• ACVS. Cranial Cruciate Ligament Disease. acvs.org

Some degree of lameness after TPLO surgery is expected. The surgery involves a bone cut and plate fixation, and the dog's leg needs weeks to heal.

The clinical challenge for owners is distinguishing between normal post-surgical lameness (which requires patience) and lameness that indicates a complication (which requires prompt veterinary attention).

The answer depends heavily on timing, trajectory, and accompanying signs.

Quick answer: Normal post-TPLO lameness should show consistent week-over-week improvement. The most common pathological causes are: surgical site infection, late meniscal tear, implant loosening, muscle atrophy, delayed bone healing, and progressive osteoarthritis. The key signal is trajectory reversal -- lameness worsening after improvement or failing to improve for 2 or more weeks.

Key takeaways

• Some lameness is normal throughout the first 8 to 12 weeks of TPLO recovery: mild limping that improves gradually over 6 to 12 weeks is typical; the key variable is trajectory
• Trajectory reversal is the key warning sign: lameness that worsens after improvement, or fails to improve for 2 or more consecutive weeks, warrants veterinary evaluation before the next appointment
• Late meniscal tear is a recognized cause of sudden lameness regression: recurrence of lameness after initial resolution can indicate meniscal injury; it occurs in 2 to 22% of TPLO cases
• Muscle atrophy is a commonly underappreciated cause of persistent lameness: the affected leg loses muscle mass during restriction; inadequate rehabilitation leaves an asymmetric gait
• Progressive osteoarthritis is the most common cause of chronic mild lameness starting months after surgery; TPLO slows but does not stop this process
• Implant failure and infection must be ruled out for lameness that is worsening or not responding to conservative management; radiographs and culture are required for diagnosis

Normal post-surgical lameness: what to expect

Week 1 to 2

Most dogs are significantly lame in the first 1 to 2 weeks. They may toe-touch only or hold the leg off the ground entirely.

This is the acute post-surgical inflammatory phase combined with the effects of anesthesia wearing off.

SustainableVet.org confirms: some lameness is expected after TPLO surgery, especially in the first few weeks; normal recovery lameness is mild limping that improves gradually over 6 to 12 weeks.

Week 2 to 6

Consistent improvement should be visible week over week. By week 4, most dogs should be bearing significant weight on the operated leg during slow walking.

Three-legged walking during activity is still common but should be decreasing.

Week 6 to 12

Most dogs should be consistently weight-bearing on the operated leg. By week 12, most are nearly normal for household activities.

Radiographic confirmation of bone healing at weeks 6 to 8 and 12 guides when activity can increase.

Pathological causes of post-TPLO lameness

1. Surgical site infection (SSI)

Timing: most commonly weeks 1 to 4, but can occur at any stage (including months later for deep implant-associated infections).

Mechanism: bacterial contamination of the incision or implant causes inflammation and pain at the plate site, which produces or worsens lameness.

Signs accompanying lameness: redness, warmth, swelling, or discharge at the incision or plate site.

Action required: same-day veterinary contact for any infection signs alongside lameness.

2. Late meniscal tear

Timing: typically weeks 4 to 12 post-surgery, though it can occur months later.

Mechanism: the meniscus, which may have been structurally weakened before surgery or had a small tear not detected at surgery, fails under load during the recovery period.

Signs accompanying lameness: audible or palpable meniscal click; pain on stifle manipulation; sudden lameness regression in a dog that had been improving.

Animal Outpatient Surgery confirms: if lameness resolves after TPLO and recurs at a later time, this can be an indication of meniscal injury.

Action required: veterinary evaluation within 24 to 48 hours; arthroscopy or arthrotomy for diagnosis and partial meniscectomy for treatment.

3. Implant loosening or failure

Timing: most common in the first 6 to 12 weeks when the osteotomy is still healing and the plate bears the full load. Can also occur later from chronic infection or late trauma.

Mechanism: excessive activity before the osteotomy heals applies forces that exceed the plate's tolerance; screws pull out or the plate bends.

Signs accompanying lameness: sudden severe lameness; pain at the plate site; sometimes audible clicking or grinding; radiographic evidence of screw loosening or plate migration.

SustainableVet.org confirms: signs of implant failure include ongoing limping, pain, swelling around the implant site, and unusual clicking or grinding sounds from the joint.

Action required: same-day emergency veterinary contact for sudden severe lameness; radiographs urgently required.

4. Muscle atrophy and weakness

Timing: most prominent from weeks 4 to 12; persists for months if rehabilitation is inadequate.

Mechanism: during activity restriction, the operated leg muscles (quadriceps, hamstrings, hip extensors) atrophy rapidly. Asymmetric muscle mass leads to asymmetric weight distribution and abnormal gait patterns that present as persistent limping.

Vetplayas confirms: limited mobility during recovery leads to muscle loss and decreased strength. This imbalance results in abnormal gait patterns and subsequent limping.

Signs: visible muscle asymmetry (operated thigh smaller than opposite); lameness that worsens with activity and improves with rest; no accompanying warmth, redness, or plate-site changes.

Action required: rehabilitation assessment; physiotherapy to rebuild muscle mass.

5. Delayed bone healing

Timing: identified at the 6 to 8 week radiographic assessment.

Mechanism: the osteotomy is not showing expected callus formation and cortical bridging. Common causes include infection, excessive activity, poor blood supply, or systemic factors (NSAIDs at high dose for extended periods, nutritional deficiencies).

Signs: persistent lameness at a level that does not match the expected trajectory; confirmed radiographically.

Action required: veterinary investigation for underlying cause; extended activity restriction; sometimes additional diagnostics (culture to rule out occult infection).

6. Delayed union or non-union

Timing: identified at 12+ weeks when bone healing should be complete.

Mechanism: the osteotomy fails to heal. The plate is subject to continued cyclic loading without the protection of consolidated bone, increasing implant failure risk.

Action required: specialist reassessment; may require bone grafting, implant revision, or extended medical management.

7. Progressive osteoarthritis

Timing: typically becomes clinically apparent after 6 to 12 months.

Mechanism: CCL disease initiates an irreversible arthritis process in the stifle. TPLO reduces but does not eliminate arthritis progression. Over months and years, arthritis produces chronic mild lameness, particularly after rest and exercise.

Signs: stiffness that improves with movement; lameness worse in cold weather or after long periods of rest; gradual worsening over months; bilateral involvement common.

SustainableVet.org (failure symptoms article) confirms: limping 2 years post-TPLO may result from arthritis, implant irritation, meniscal damage, or muscle atrophy.

Action required: long-term management (joint supplements, weight management, NSAIDs for flares, hydrotherapy, physiotherapy).

8. Contralateral CCL rupture

Timing: any time during or after recovery from the first TPLO.

Mechanism: the contralateral CCL, subject to the same degenerative process and bearing extra load during recovery, may rupture. The dog appears to start limping on the opposite leg.

Signs: what appears to be recovery from one side suddenly accompanied by new lameness on the opposite side; the dog may be lame on a different leg or bilateral.

Action required: veterinary evaluation; bilateral CCL disease may require staged or simultaneous bilateral TPLO.

How to assess the trajectory at home

Create a simple weekly log: note the leg-use pattern (full bearing, toe-touching, three-legged) and the dog's willingness to walk at each prescribed walk time.

Compare week 4 to week 3, week 6 to week 5. If the pattern is consistently improving, continue the protocol. If it is static or worsening, contact your vet.

For the lameness guide, see lameness after TPLO surgery in dogs. For the TPLO failure signs guide, see signs of TPLO failure in dogs and when to see a vet.

For the meniscal tear guide, see dog meniscus tear after TPLO surgery. For the infection guide, see earliest signs of TPLO infection.

Frequently asked questions

My dog was progressing well at week 4 but is limping more at week 5. What do I do?

A single week of regression after a period of progress is not necessarily pathological -- increased activity, weather changes, or an off day can cause temporary setbacks.

But if the worsening persists for 2 weeks, or is accompanied by any infection signs, contact your vet.

Monitor closely and reduce activity to the week 2 level for 24 to 48 hours to see if the leg settles.

My dog is still limping 4 months after TPLO surgery. Is this normal?

Mild residual lameness can persist to 4 months, particularly in older dogs or those with significant muscle atrophy.

However, lameness at 4 months that is not showing week-over-week improvement warrants a veterinary assessment.

A radiograph will confirm bone healing status; physical examination will assess muscle mass and stifle range of motion.

My dog is limping on the opposite leg during TPLO recovery. What does that mean?

This raises concern for contralateral CCL disease. The opposite leg is bearing extra load during recovery and may have already been compromised.

A new limp on the opposite leg during recovery warrants veterinary evaluation, including assessment and radiographs of the contralateral stifle.

Can physiotherapy reduce long-term limping?

Yes, significantly. Rebuilding the atrophied quadriceps and hip extensor muscles through controlled hydrotherapy, cavaletti exercises, and progressive strength work reduces the compensatory gait patterns that produce chronic post-TPLO lameness.

Weight management is equally important -- every additional kilogram of body weight increases stifle load.

When is limping after TPLO an emergency?

Sudden complete non-weight bearing (holding the leg entirely off the ground) after a period of normal improvement is an emergency call. Same-day emergency veterinary contact is appropriate for this presentation.

Gradual worsening that does not resolve within 24 to 48 hours is a next-day call.

Resources

• SustainableVet. Common Causes of Limping in Dogs Post-TPLO Surgery. sustainablevet.org
• Animal Outpatient Surgery. What Are the Most Common Complications of TPLO Surgery in Dogs? animaloutpatientsurgery.com
• SustainableVet. Lameness After TPLO Surgery in Dogs. sustainablevet.org
• Laveen Vet Center. Dog Limping 1 Year After TPLO Surgery. laveenvetcenter.com

"Failure rate" is used loosely when owners discuss TPLO, which can cause significant confusion. A complication is not the same as a failure.

Understanding what the published data actually shows and distinguishing minor complications from true surgical failures gives owners a much clearer picture of what to expect.

Quick answer: The overall TPLO complication rate is 10 to 34% across studies; most are minor. Major complications requiring reoperation occur in 2 to 7%. Infection is the most common major complication. Long-term good outcomes are reported in 90 to 93% of dogs.

Key takeaways

• Overall complication rate is 10 to 34% across published studies; most complications are minor and resolve without additional surgery
• Major complication rate requiring reoperation is 2 to 7%: a 1,000-dog study found 14.8% overall with 6.6% major complications
• SSI is the most common major complication: 2.9% to 25.9% across studies; giant breeds over 50 kg are at highest risk
• Small dogs under 15 kg have significantly lower complication rates: 4.44% in one 90-dog study, with no revisions
• Good to excellent long-term outcomes in 90 to 93% of dogs: the complication rate does not equal the failure rate
• Surgeon experience is the most modifiable risk factor: complication rates are consistently lower at high-volume specialty centers with board-certified surgeons

Defining "failure" vs. "complication"

This distinction is critical for interpreting the literature and for setting owner expectations accurately.

Complication: any deviation from the expected post-operative course. This includes minor findings like superficial wound dehiscence, mild swelling, or radiographic evidence of delayed osteotomy healing with no clinical signs. Many publications include these minor events in their complication rates.

Major complication: an event requiring additional surgical intervention or causing extended lameness. Major complications represent the subset of complications that meaningfully affect recovery and outcome.

Failure: the most restrictive definition surgery that did not achieve its goal of stifle stabilization, resulting in persistent instability and requiring revision with a different technique. True failure in this sense is uncommon after TPLO.

What published complication data shows

Overall complication rates

Vetamac confirms: complication rates following TPLO surgery range from 14% to 34%, with less than 10% of cases requiring a second surgery.

PMC (intraoperative bacterial culture study) confirms: the complication rate of TPLO varies between 10% and 34%, with 2 to 4% requiring surgical revision.

Today's Veterinary Practice reports a 14.8% complication rate in 1,000 TPLO patients (6.6% major — requiring repeat surgery or extended lameness), including 2.8% late meniscal injury and 6.6% infections.

Infection rates

Infection is the most common major complication and the one with the greatest variation by dog size and surgical setting.

PMC confirms: SSI rate after TPLO is reported to be 2.9% to 25.9% across studies, which is higher than other clean orthopedic surgeries (2.0 to 6.7%).

Surgical site infection rates of 21.3% to 25.9% have been reported specifically for giant-breed dogs weighing over 50 kg.

The implant removal rate due to infection is 3 to 7.4% per published literature (PMC PRP study; ResearchGate implant removal study).

Complication rates by dog size

Dog size is a consistent predictor of complication risk.

PLOS One retrospective (90 dogs under 15 kg): overall complication rate 4.44%, with no complications requiring surgical revision.

The study confirms: the complication rate in dogs under 15 kg is less than that historically reported in heavier dogs.

PubMed retrospective (small and medium dogs, 2.0 and 2.7 mm plates): overall complication rate 36%.

The most common complications were radiographic evidence of delayed healing (9%), patellar tendon thickening (8%), and tibial tuberosity fracture (6%). Only 7% of complications were major.

PLOS One confirms: the TPLO complication rates range from 10% to 34% and vary in severity from swelling and bruising to fractures and osteomyelitis.

Implant-related complications reportedly occur in under 10% of all TPLO procedures.

Long-term success rates

Complication rates must be interpreted alongside long-term success rates.

The retrospective cohort study comparing TPLO, Tightrope, and TTA found: function greater than 1 year after surgery was 93.1% for TPLO, 92.7% for Tightrope, and 89.2% for TTA.

SustainableVet.org confirms: good to excellent long-term outcomes are achieved in 90.4% of patients up to 6.8 years after TPLO surgery; 80 to 90% of owners are satisfied with their dog's long-term recovery.

A dog can have a complication even a significant one like an infection and still achieve a good long-term outcome after the complication is resolved.

The complication rate and the long-term success rate address different aspects of the outcome.

Factors that affect complication and failure rates

Surgeon experience and volume

This is the most consistently cited modifiable risk factor. High-volume specialty centers and board-certified surgeons consistently report lower complication rates than general practitioners performing occasional TPLO procedures.

Surgical efficiency, technique precision, and post-operative protocol standardization all contribute.

Dog size and body weight

Larger dogs generate higher joint forces, have larger dead space at the surgical site, and place more mechanical demand on the implant during healing.

These factors contribute to the higher complication rates seen in large and giant breeds.

Excessive tibial plateau angle (TPA)

Dogs with TPA above 35 degrees (excessive TPA, or eTPA) have higher complication rates.

Today's Veterinary Practice notes: owner-perceived outcome was superior for eTPA group dogs when TPLO resulted in TPA of 14 degrees or less compared to those with TPA greater than 14 degrees.

Postoperative complications were more common in dogs with eTPA.

Post-operative activity restriction compliance

Dogs that are over-active during recovery have higher rates of implant complications, seroma formation, and wound complications.

Strict adherence to the prescribed restriction protocol is the owner's primary contribution to reducing complication risk.

For the complications overview, see 15 common complications after TPLO surgery in dogs. For the infection signs guide, see TPLO plate infection signs and treatment.

For the long-term outcomes guide, see long-term outcomes of TPLO surgery. For the plate removal guide, see TPLO plate removal recovery guide.

Frequently asked questions

What is the TPLO failure rate?

Depends on how "failure" is defined. If failure means any complication: 10 to 34% across studies. If failure means major complications requiring surgery or causing extended lameness: 2 to 7%.

If failure means persistent instability requiring revision with a different technique: uncommon and not consistently reported across large series.

Is TPLO safe for large breed dogs?

Yes, but with a higher complication risk than small dogs. Vetamac confirms: for large breeds, TPLO is still the gold standard, providing better long-term stability than alternatives.

The higher complication rate in large dogs reflects the greater mechanical demands and surgical challenges, not a fundamental unsafety of the procedure.

What percentage of TPLO dogs need a second surgery?

Across published studies, 2 to 10% require a second surgical intervention. Most second surgeries address infection (requiring plate removal), late meniscal tears (requiring partial meniscectomy), or implant complications.

Does my dog's vet experience affect failure rate?

Yes, substantially. Surgeons performing fewer than a set number of TPLO procedures per year have higher complication rates than high-volume specialists.

This is one reason referral to a board-certified orthopedic surgeon (ACVS diplomate) is recommended for TPLO.

If my dog has a complication, does that mean the TPLO failed?

Not necessarily. Many dogs who develop complications including infections requiring plate removal still achieve good to excellent long-term function after the complication is resolved.

The complication rate and the long-term outcome are different measures.

Resources

• Today's Veterinary Practice. Canine Cranial Cruciate Disease: Evidence-Based Look at Current Treatment Modalities. todaysveterinarypractice.com
• PLOS One. Risk Factors for Short-Term Postoperative Complications in Dogs Weighing Less Than 15 kg. journals.plos.org
• PubMed. Short-Term Complications Associated With TPLO in Dogs Using 2.0 and 2.7 mm Plates. pubmed.ncbi.nlm.nih.gov
• PMC. Clinical Relevance of Positive Intraoperative Bacterial Culture in TPLO in Dogs. ncbi.nlm.nih.gov
• Vetamac. TPLO Surgery for Dogs: Success Rates and Alternative Options. vetamac.com

TPLO has a high overall success rate, but complications do occur. The published overall complication rate ranges from 10 to 34%, with most complications being minor and manageable.

Knowing what to watch for -- and when a sign requires a same-day call vs. a mention at the next scheduled appointment -- allows owners to respond appropriately.

Quick answer: The 15 most common post-TPLO complications: surgical site infection, seroma, implant loosening or failure, osteomyelitis, late meniscal tear, tibial tuberosity fracture, delayed bone healing, persistent lameness, non-union, intra-articular screw placement, nerve damage, patellar tendon thickening, patellar luxation, progressive osteoarthritis, and contralateral CCL rupture. Most are minor and manageable.

Key takeaways

• The overall complication rate is 10 to 34%: most complications are minor (swelling, mild infection); serious complications such as implant failure or osteomyelitis are less common
• SSI is the most frequent single complication: reported in 2.9% to 17.3% of TPLO procedures; most are superficial and treatable with antibiotics if caught early
• Late meniscal tear occurs in 1.8% to 10.5% of cases where the meniscus was normal at surgery; it presents as sudden lameness return with meniscal click
• Tibial tuberosity fracture is reported in 1 to 9% of TPLO cases: incorrect positioning and oversized saw blades are the main risk factors
• Implant-associated infection occurred in 3.4% and osteomyelitis in 0.6% across numerous studies; osteomyelitis requires strong antibiotics for 4 to 6 months and sometimes plate removal
• Contralateral CCL rupture is a significant long-term risk: 30 to 40% of dogs develop rupture of the opposite CCL; owners should monitor the opposite stifle

Early complications (weeks 0 to 8)

1. Surgical site infection (SSI)

The most common complication. SSI ranges from superficial incisional infection (treatable with oral antibiotics and wound care) to deep implant-associated infection requiring plate removal.

Signs: redness spreading beyond the incision, warmth, swelling, cloudy or malodorous discharge.

Incidence: 2.9% to 17.3% per published literature; the PMC 769-TPLO study (769 procedures) found 8.5%.

Management: culture-directed antibiotics for superficial infections; surgical debridement and sometimes plate removal for deep implant infections.

2. Seroma

A localized collection of clear serous fluid under the skin near the incision, typically appearing 1 to 3 weeks post-surgery.

Signs: soft, fluctuant swelling at or near the incision; no warmth or redness; clear fluid if aspirated.

Incidence: common; most resolve without treatment.

Management: monitoring; aspiration if large or causing discomfort; bandaging in some cases.

3. Acute lameness from overactivity

The dog is over-active during the restriction period and bears too much load on the plate before the osteotomy heals.

Signs: sudden worsening of lameness after a period of improvement; may indicate implant stress or early failure.

Management: strict crate rest; radiographic assessment to rule out implant displacement.

4. Wound dehiscence

The incision edges separate before fully healing. More common in dogs that lick the incision despite an e-collar that fits incorrectly.

Signs: open wound edges, sometimes with tissue visible.

Management: cleaning and re-closure in most cases; e-collar compliance review.

Mid-term complications (weeks 4 to 16)

5. Delayed bone healing

The osteotomy is not showing expected consolidation on radiographs at the 6 to 8 week checkpoint.

Signs: radiographic evidence of widening osteotomy gap or absence of callus formation; may or may not produce clinical signs.

Risk factors: infection, excessive activity, poor bone quality (older dogs, large breeds), NSAIDs at high doses for extended periods.

Management: extended activity restriction; investigate for underlying infection; nutritional support.

6. Tibial tuberosity fracture

A fracture of the tibial tuberosity (the prominence where the patellar tendon attaches) caused by the osteotomy saw blade coming too close to this structure.

Incidence: 1 to 9% per Laguna Woods Vets; higher in dogs with high TPA, high body weight, and large TPA change.

Signs: acute severe lameness; radiographic evidence of fracture.

Management: surgical repair or conservative management depending on displacement.

7. Late meniscal tear

A meniscal tear occurring after TPLO in a meniscus that appeared normal at surgery. See the dedicated meniscal tear article for full detail.

Incidence: 1.8% to 10.5% of cases with normal meniscus at TPLO (Dog Discoveries).

Signs: sudden lameness regression; meniscal click on movement; pain on stifle manipulation.

Management: partial meniscectomy.

8. Implant loosening or failure

The plate or screws shift, bend, or break -- typically from premature overactivity before the osteotomy heals.

Signs: sudden severe lameness; pain at plate site; radiographic evidence of screw loosening, plate migration, or osteotomy displacement.

Management: revision surgery in most cases of significant displacement.

Long-term complications (months 3 and beyond)

9. Osteomyelitis

Bone infection extending from a superficial SSI or introduced via hematogenous seeding. Difficult to treat.

Incidence: 0.6% per Dog Discoveries citing multiple studies.

Signs: persistent lameness; draining tract; radiographic bone destruction, periosteal reaction, or sequestrum.

Management: Laguna Woods Vets confirms osteomyelitis requires strong antibiotics for 4 to 6 months; a wound culture aids antibiotic selection; plate removal is often required.

10. Non-union

The osteotomy fails to heal, resulting in permanent instability at the cut site.

Risk factors: infection, inadequate fixation, excessive motion, poor blood supply.

Signs: persistent lameness; radiographic evidence of osteotomy gap persisting beyond 16 weeks with no bridging callus.

Management: revision surgery, bone grafting, and often implant revision.

11. Intra-articular screw placement

A screw tip violates the joint space, causing joint damage and persistent pain. Best identified on the postoperative radiograph.

Signs: ongoing lameness; pain on stifle range of motion; radiographic evidence of screw in joint space.

Management: removal of the offending screw.

12. Persistent lameness without identifiable cause

Some dogs have persistent mild lameness despite uncomplicated bone healing and no identifiable complication. This may reflect residual arthritis progression, muscle atrophy, or subclinical meniscal issues.

Management: rehabilitation, joint supplements, and management of secondary osteoarthritis.

13. Patellar tendon thickening

Fibrous thickening of the patellar tendon develops in some TPLO dogs over time. This is typically not clinically significant.

Signs: palpable thickening of the patellar tendon on examination; usually incidental finding.

Management: generally none required; physiotherapy in some cases.

14. Patellar luxation

Medial patellar luxation can develop or worsen after TPLO, particularly if the plate is contoured in a way that affects patellar tracking.

Signs: intermittent lameness, popping of the patella medially on examination.

Management: surgical correction (trochleoplasty and tibial crest transposition) in symptomatic cases.

15. Progressive osteoarthritis

All dogs with CCL disease develop some arthritis progression regardless of surgical technique. TPLO slows but does not stop this process.

Signs: gradual stiffness, lameness that is worse after rest, reduced activity tolerance.

Management: joint supplements (omega-3 fatty acids, glucosamine), weight management, NSAIDs for flares, hydrotherapy.

Contralateral CCL rupture: a special consideration

Contralateral CCL rupture is not a complication of TPLO but deserves mention.

Midvalley Animal Clinic confirms it is very common (30 to 40% of patients) for both knees to develop this ligament injury.

Owners of dogs that have had unilateral TPLO should monitor the opposite stifle for early signs.

For the infection guide, see TPLO plate infection signs and treatment. For the meniscal tear guide, see dog meniscus tear after TPLO surgery.

For the failure rate overview, see TPLO failure rate in dogs. For the implant failure signs, see TPLO implant failure signs and causes.

Frequently asked questions

What is the most common serious complication after TPLO?

Deep implant-associated infection requiring plate removal is the most common serious complication, with an implant removal rate of 3.5 to 7.5% of procedures (ResearchGate).

Osteomyelitis (0.6%) and tibial tuberosity fracture (1 to 9%) are other serious but less common complications.

Is a 10 to 34% complication rate high for an orthopedic surgery?

The range is real but the majority of complications are minor -- a seroma, mild superficial infection treated with antibiotics, or a brief period of increased lameness.

Serious complications requiring revision surgery are significantly less common. TPLO's overall success rate (93% limb function restoration at 1 year per a 2013 study) reflects that most dogs recover well.

Can complications be prevented?

Most can be reduced in risk but not eliminated.

Owner-controlled risk reduction: e-collar compliance, strict activity restriction for 8 to 12 weeks, daily incision inspection, and attending all scheduled vet appointments.

What happens if my dog develops two complications simultaneously?

This is uncommon but does occur (for example, SSI leading to delayed bone healing). Management is coordinated by your surgical team based on the severity and interaction of the complications.

Contact your vet immediately for any concern.

Should I be worried every time my dog limps?

A degree of lameness is expected throughout the recovery period. The key signal is trajectory: steadily improving lameness is expected; suddenly worsening or reversed lameness is not.

Monitor for any sudden changes and contact your vet for trajectory reversals.

Resources

• PMC. Surgical Site Infection After 769 TPLOs. pmc.ncbi.nlm.nih.gov
• Laguna Woods Vets. TPLO Surgery Complications. lhah.com
• Dog Discoveries. TPLO Failure and Complications in Dogs. dogdiscoveries.com
• Clinician's Brief. Common Tibial Plateau-Leveling Osteotomy Complications. cliniciansbrief.com

CCL (cranial cruciate ligament) rupture is one of the most common orthopedic injuries in dogs.

Canine CCL rupture often develops gradually through progressive degeneration. Early signs are subtle and easy to dismiss as aging or a minor sprain.

Recognizing the signs early improves outcomes because partial tears can progress to complete ruptures if not addressed.

Quick answer: Common signs a dog may need TPLO surgery: persistent rear limb limping, stiffness after rest, toe-touching gait, sitting with one rear leg extended (positive sit test), stifle swelling and warmth, and sudden non-weight bearing. A drawer test and radiographs confirm CCL rupture.

Key takeaways

• Hind limb lameness is the most common presenting sign: any dog with a persistent rear leg limp warrants veterinary evaluation; CCL rupture is the most common orthopedic cause
• The classic sitting posture change is highly specific: a dog now sitting with one rear leg extended to the side rather than tucked under is compensating for stifle pain (positive sit test)
• Intermittent lameness that comes and goes may indicate a partial tear: partial tears progress to complete ruptures in most dogs without treatment
• Stiffness after rest or sleep is a common early sign: the dog seems fine after moving around but is stiff when first rising
• Non-weight bearing or acute severe lameness after activity indicates a complete CCL rupture; the dog holds the leg entirely off the ground
• Both stifles are at risk: 30 to 40% of dogs develop CCL rupture in both knees over time; monitor the opposite side in any dog with known CCL disease

The 13 signs

1. Hind limb limping after exercise

The dog walks normally at rest but limps noticeably after running, playing, or climbing stairs. The limping may resolve after 10 to 30 minutes of rest.

This pattern suggests the joint can handle low-level loading but is symptomatic under increased mechanical stress.

SustainableVet.org confirms: occasional limping may come and go, especially after exercise or long walks; some days may seem better than others, but this inconsistency is a sign of joint problems.

2. Toe-touching gait (barely bearing weight)

The dog walks with most weight on three legs, barely resting the toes of the affected rear limb on the ground.

The toe touches down for stability and ground contact but carries almost no weight.

SustainableVet.org confirms: the dog may lightly place just the toes of the affected leg on the ground without putting full weight on it; this is a common sign of knee pain.

Coldwater Online confirms: sitting with the leg kicked out to the side is a classic signal.

3. Sitting with one rear leg extended to the side (positive sit test)

A dog with stifle pain cannot comfortably flex the knee to a normal sitting position. Instead, the affected leg extends out to the side while the dog sits.

This is reproducible and highly suggestive of stifle pathology.

AESC confirms: dogs with CCL tears often sit with one leg stuck out to the side rather than tucked normally.

4. Stiffness after rest or sleep

The dog gets up from sleeping or lying and is noticeably stiff and lame for the first few minutes. After moving around, the stiffness resolves.

This is the classic pattern of joint inflammation: fluid redistribution during rest causes stiffness that is mobilized by movement.

Coldwater Online confirms: stiffness after rest, especially in the morning or after a nap, is a classic early signal.

5. Reluctance to go up or down stairs

Climbing stairs requires repetitive stifle flexion and load bearing. A dog with a partial or complete CCL tear shows hesitation or refusal to use stairs, often pausing at the base or top.

6. Reluctance to jump into the car or onto furniture

Loading into the car from the ground requires a pushing-off motion from the rear legs with sudden stifle extension. Dogs with CCL pain become reluctant to perform this movement.

7. Muscle atrophy of the rear leg

The quadriceps and hamstring muscles of the affected leg visibly reduce in size compared to the opposite leg. This occurs because the dog guards the painful limb and reduces loading over time.

Noticeable asymmetry in thigh circumference is a sign of chronic or progressive CCL disease.

8. Swelling at the stifle joint

The stifle (knee) joint becomes palpably enlarged.

The medial compartment (inside of the knee) often shows a visible soft tissue swelling called a medial buttress -- fibrous tissue that develops in response to chronic joint instability.

The joint may feel warm compared to the opposite stifle.

MetLife Pet Insurance confirms: the stifle area may appear swollen or feel warm to the touch.

9. Audible popping or clicking from the knee

Meniscal damage accompanies CCL rupture in approximately 40 to 60% of chronic cases.

When the unstable tibia slides across the femoral condyles, it may crush or tear the meniscus, producing an audible clicking or popping sound.

AESC confirms: popping noises as the knee joint moves may be heard and are a sign of possible meniscal involvement.

10. Sudden complete non-weight bearing after activity

The dog was running, playing, or jumping, then suddenly cried out and completely stopped using the rear leg. This acute presentation indicates a sudden complete CCL rupture.

Unlike gradual partial tears, complete acute ruptures are painful and dramatic at onset.

Sandringham Vet confirms: most dogs with a CCL tear will avoid putting weight on the affected leg; difficulty standing up or sitting from a resting position is common after complete rupture.

11. Chronic intermittent lameness with improvement then worsening

The dog limps, seems to improve, then worsens again. This cyclical pattern often reflects a partial tear progressing with activity then settling with rest.

Without treatment, partial tears progress to complete ruptures in most dogs.

12. Both rear legs showing signs simultaneously

Some dogs present with bilateral CCL disease -- both stifles partially or completely ruptured.

These dogs show a characteristic bunny-hopping gait (using both rear legs together rather than alternating) or severe difficulty rising.

Midvalley Animal Clinic notes 30 to 40% of patients will develop CCL rupture in both knees over time.

13. Hindquarters weakness or instability during activity

The dog's rear end seems weak or gives way during turning, running, or on uneven terrain. This reflects dynamic instability of the stifle under load rather than pain at rest.

How the diagnosis is confirmed

Signs alone are not sufficient for definitive diagnosis. Veterinary confirmation requires:

Physical examination tests

Tibial thrust test: the vet applies cranial-directed force to the hock while stabilizing the femur. In a CCL-deficient stifle, the tibia slides forward under this force.

Drawer test: with the dog sedated or relaxed, the vet grasps the femur and tibia and attempts to slide them in opposite directions. Forward movement of the tibia relative to the femur (cranial drawer) confirms CCL rupture.

Chewy confirms: your veterinarian will check for tibial thrust -- abnormal sliding of femur and tibia. A positive drawer test confirms CCL rupture is very likely.

Radiographs

X-rays assess joint fluid accumulation (which causes fat pad displacement on the lateral view -- the "fat pad sign"), early arthritis changes, and tibial plateau angle (TPA) measurement for surgical planning.

Radiographs do not directly image the CCL but confirm the secondary changes of CCL disease.

Arthroscopy or arthrotomy

At the time of surgery, the surgeon directly inspects the CCL and menisci. This provides the definitive diagnosis and allows concurrent meniscal treatment.

For the TPLO surgery overview, see what causes TPLO surgery to be needed in dogs. For alternatives, see alternatives to TPLO surgery for dogs.

For TPLO vs lateral suture, see lateral suture vs TPLO for dogs. For surgery preparation, see preparing for your dog's TPLO surgery.

Frequently asked questions

Can a dog with a CCL tear recover without surgery?

Partial tears in very small dogs (under 10 to 15 kg) sometimes stabilize with strict rest and conservative management.

For most dogs, particularly those over 15 to 20 kg, conservative management does not restore normal joint stability and the lameness persists or worsens.

Complete ruptures in any dog over about 15 kg typically require surgery for full functional recovery.

How quickly does a CCL tear progress if untreated?

A partial tear typically progresses to a complete rupture within weeks to months if activity is not restricted. Arthritis develops progressively from the moment the joint becomes unstable.

Early treatment reduces arthritis progression and improves long-term outcomes.

My dog limped once and then seemed fine. Should I go to the vet?

Yes, if the limp was in a rear leg and involved guarding or reduced weight bearing. A single episode of rear limb lameness lasting more than a few minutes warrants evaluation.

Early CCL tears can produce episodic lameness that resolves with rest -- evaluation while the dog appears normal can still reveal joint instability or effusion on examination.

Does the dog need sedation for the drawer test?

Sedation often improves accuracy. A dog in pain or a large, tense dog may resist examination sufficiently to produce a false-negative drawer test.

Sedation allows full relaxation and more reliable assessment of drawer and tibial thrust.

Which breeds are most at risk for CCL rupture?

Dispomed confirms high-risk breeds include Rottweilers, Newfoundlands, Staffordshire Terriers, Mastiffs, Akitas, Saint Bernards, Labrador Retrievers, and Chesapeake Bay Retrievers. Neutered dogs are at higher risk than intact dogs of the same breed.

Obesity and poor physical condition also increase risk.

Resources

• SustainableVet. 13 Signs Your Dog May Need TPLO Surgery. sustainablevet.org
• AESC Parker. TPLO Surgery in Dogs: Frequently Asked Questions. aescparker.com
• MetLife Pet Insurance. TPLO Surgery for Dogs. metlifepetinsurance.com
• ACVS. Cranial Cruciate Ligament Disease. acvs.org