Patellar luxation is a common orthopedic condition in dogs—especially small and toy breeds—characterized by displacement of the patella from the trochlear groove. Although medial patellar luxation (MPL) is most common, lateral patellar luxation (LPL) also occurs, particularly in larger breeds. When luxation is associated with malalignment of the quadriceps mechanism, trochlear hypoplasia, or tibial/femoral deformities, corrective osteotomy is required to restore normal biomechanics.

Corrective osteotomy—performed alone or in combination with soft-tissue procedures—addresses the underlying bony conformation abnormalities responsible for patellar displacement. The most common osteotomies include tibial tuberosity transposition (TTT), closing wedge distal femoral osteotomy (cDFO), opening wedge osteotomy, and torsional corrections applied to the femur or tibia.

I. Indications for Corrective Osteotomy

Corrective osteotomy is indicated when patellar luxation is accompanied by underlying skeletal deformities such as:

A. Tibial Tuberosity Malalignment

• Medial displacement → medial patellar luxation

• Lateral displacement → lateral patellar luxation
  This is the most common bony contributor to MPL.

B. Distal Femoral Varus or Valgus

• Medial luxation is often accompanied by distal femoral varus

• Lateral luxation typically features distal femoral valgus

This necessitates distal femoral osteotomy for realignment.

C. Femoral Torsion Abnormalities

• Excessive internal rotation of the femur contributes to MPL

• Excessive external rotation can predispose to LPL

D. Tibial Torsion

Rotational abnormalities of the tibia may require rotational osteotomy when severe.

E. Recurrent or Failed Patellar Luxation Repair

Particularly when soft-tissue procedures (e.g., imbrication, release) were performed without addressing underlying bone malalignment.

F. Grade III–IV Patellar Luxation

High-grade luxations frequently require combined bony and soft-tissue correction.

II. Preoperative Assessment and Planning

Corrective surgery begins with accurate quantification of the underlying deformity.

1. Orthogonal Radiographs

Include:

• Pelvis to tarsus

• Femur length views

• Skyline patella/trochlear views

2. Computed Tomography

CT is strongly recommended for:

• Determining femoral/tibial torsion

• Measuring mechanical and anatomical axes

• Preoperative planning of osteotomy angle and wedge size

3. Mechanical Axis Evaluation

Assess:

• Quadriceps alignment relative to the trochlear groove

• Hip–stifle–hock alignment

• Degree of varus/valgus deformity

4. Trochlear Groove Assessment

Hypoplasia or shallow grooves benefit from:

• Trochlear block recession

• Trochlear wedge recession

5. Review of Concurrent Orthopedic Problems

• CrCL insufficiency

• Coxofemoral dysplasia

• Contralateral limb deformities

III. Surgical Techniques

Corrective osteotomy is typically combined with soft-tissue balancing and trochleoplasty.

A. Tibial Tuberosity Transposition (TTT)

TTT is indicated when malalignment of the patellar tendon pulls the patella medially or laterally.

Surgical Steps

1. Expose the proximal tibia via medial or lateral parapatellar approach.

2. Create an osteotomy of the tibial tuberosity, preserving distal periosteal hinge when possible.

3. Translate the tuberosity medially or laterally to realign the patellar tendon with the trochlear groove.

4. Fixation using:

   • K-wires

   • Tension-band wire

   • Pins alone (in toy breeds)

   • Small T-plates (in larger dogs)

5. Confirm alignment via intraoperative radiography.

Biomechanical Goal

Realign quadriceps pull to center the patella during stifle flexion and extension.

B. Distal Femoral Osteotomy (DFO)

Indicated when mechanical axis deviation arises from distal femoral varus or valgus.

Closing Wedge DFO (most common)

Used for correcting distal femoral varus (MPL cases).

Surgical Steps

1. Identify osteotomy level distal to the femoral isthmus and proximal to the trochlea.

2. Create a pre-measured wedge based on preoperative planning (CT preferred).

3. Remove the wedge, carefully maintaining alignment.

4. Realign femur, correcting mechanical axis deviation.

5. Fixation using locking plate (LCP) or DFO-specific plate.

Opening Wedge DFO

Used less commonly but valuable when limb length preservation is important.

C. Femoral Torsional Osteotomy

Indicated for abnormal torsion values:

• Excessive internal rotation (> 40–45°): MPL

• Excessive external rotation (> 40–45°): LPL

Technique Summary

• Perform transverse osteotomy at femoral diaphysis

• Rotate distal segment to predetermined degree

• Fix with locking plate

D. Tibial Rotational Osteotomy

Less common but useful when tibial torsion significantly contributes to luxation.

E. Trochleoplasty (Often Performed Together)

1. Block Recession Trochleoplasty

Preferred due to superior patellar tracking and preservation of articular cartilage.

2. Wedge Recession Trochleoplasty

Useful in smaller patients.

3. Abrasion or Chondroplasty (Not recommended in adults)

F. Soft-Tissue Balancing

Soft tissue procedures complement osteotomy:

• Medial release for MPL

• Lateral imbrication for MPL

• Opposite adjustments for LPL

• Capsular and retinacular balancing

These improve patellar tracking after bony correction.

IV. Postoperative Care

1. Activity Restriction

• Strict confinement 6–8 weeks

• Controlled leash walks only

• No running, jumping, or stairs

2. Incision Monitoring

• Check twice daily

• Prevent licking with e-collar

• Watch for infection or excessive swelling

3. Radiographic Follow-Up

• 6 weeks: healing assessment

• 10–12 weeks: return-to-activity clearance

4. Rehabilitation

Rehab significantly improves recovery:

• PROM exercises

• Hydrotherapy

• Controlled strengthening

V. Complications

Common issues include:

• Implant irritation (K-wires, especially after TTT)

• Patellar reluxation (often due to uncorrected bone deformity)

• Delayed union or nonunion at osteotomy site

• Tibial crest fracture

• Over- or under-correction of angular deformity

CT-based planning significantly reduces the risk of under-correction.

VI. Prognosis

With proper correction of underlying skeletal deformity, prognosis is excellent:

• Most patients regain full and pain-free function

• Recurrence rates are low when both soft tissue and bone alignment are corrected

• Early, structured rehab accelerates return to normal movement

High-grade luxations and large breed dogs have less predictable outcomes but still benefit markedly from corrective osteotomy combined with soft tissue procedures.

FAQs: Corrective Osteotomy for Patellar Luxation

1. When is corrective osteotomy indicated over soft-tissue procedures alone?

Corrective osteotomy is required when patellar luxation is caused by an underlying bony deformity, such as tibial tuberosity malalignment, distal femoral varus/valgus, femoral torsion abnormalities, or significant tibial torsion. Grade III–IV luxations and recurrent cases also strongly indicate osteotomy.

2. How do I determine whether femoral deformity is contributing to the luxation?

Perform mechanical axis evaluation using orthogonal radiographs or CT. Distal femoral varus is common in MPL; valgus in LPL. CT improves accuracy in calculating wedge size for DFO and quantifying torsional abnormalities.

3. Should trochlear recession be performed in all cases?

Most Grade II–IV luxations have trochlear hypoplasia, so block or wedge recession is routinely performed. A normal-depth groove may not require recession, but this is uncommon in high-grade luxation.

4. What are the main indications for Tibial Tuberosity Transposition (TTT)?

TTT corrects quadriceps mechanism malalignment. It is essential whenever the patellar tendon does not align with the center of the trochlear groove—most often in MPL due to medial displacement of the tuberosity.

5. How much should the tibial tuberosity be translated?

Translate until the patellar tendon lies directly over the central trochlear groove during neutral limb position. CT alignment and intraoperative fluoroscopy increase precision.

6. When should I perform a Distal Femoral Osteotomy (DFO)?

A DFO is indicated when mechanical axis deviation exceeds:

• >5–7° of distal femoral varus (MPL)

• >6–8° of distal femoral valgus (LPL)
  Correcting the deformity substantially reduces reluxation rates.

7. Closing wedge vs. opening wedge DFO—how do I choose?

Closing wedge DFO is most common and biomechanically stable. Opening wedge DFO may be selected when maintaining limb length is essential, but requires robust internal fixation (usually locking plates).

8. How do I evaluate femoral or tibial torsion?

CT is the gold standard.
Abnormal torsion guidelines:

• Femoral internal torsion > 40–45° → MPL

• Femoral external torsion > 40–45° → LPL
  Tibial torsion evaluation is similar but less often clinically significant.

9. Which fixation method is preferred for DFO?

A locking compression plate (LCP) provides the most reliable stability, especially in opening wedge procedures or large-breed dogs. Reconstruction plates may be used for closing wedge osteotomies with good bone contact.

10. What are the most common complications after corrective osteotomy?

• Patellar reluxation due to incomplete correction

• Implant irritation (particularly TTT pins)

• Tibial crest fracture

• Delayed union or nonunion at osteotomy site

• Over- or under-correction of angular deformity

• Persistent lameness due to missed torsional deformity

Proper preoperative planning and CT-based measurements significantly reduce complications.

11. How soon can patients return to normal activity?

Radiographic healing of osteotomies typically takes 8–12 weeks. Controlled rehab begins at 4–6 weeks, with gradual return to activity around 10–14 weeks, depending on the osteotomy type and implant stability.

12. What is the recurrence rate after corrective osteotomy?

When both bone deformity and soft tissues are corrected, recurrence rates are low (<5%). The highest recurrence is seen in large-breed dogs with unaddressed torsion or femoral varus.