Presentation Title: Patellectomy – Anatomy, Biomechanics, Management and Physiotherapy Rehabilitation

This presentation provides a comprehensive overview of Patellectomy, a surgical procedure involving the removal of the patella, commonly performed in cases of severe comminuted fractures, infection, or chronic patellofemoral pain not responsive to conservative treatment.

The session begins with a review of the anatomy of the patella and its vital role in enhancing the biomechanical efficiency of the quadriceps mechanism by increasing the lever arm and torque production during knee extension. The biomechanical changes following patellectomy—including loss of quadriceps strength, altered joint forces, and reduced knee stability—are discussed in detail to highlight the clinical impact of patellar removal.

Further, the presentation outlines surgical and postoperative management, followed by a structured physiotherapy rehabilitation protocol. The rehab program emphasizes gradual restoration of knee mobility, quadriceps re-education, muscle strengthening, gait training, and functional recovery, progressing from early protected motion to advanced functional exercises.

Overall, the presentation integrates anatomy, biomechanics, surgical considerations, and evidence-based physiotherapy protocols to provide a clear understanding of comprehensive patient care following patellectomy.

1. Patellectomy Rehabilitation Naeem Rahbar

2. Introduction A patellectomy is a surgical procedure to remove all or part of the patella (kneecap). It is considered a last resort for severe conditions like shattered patellar fractures, advanced arthritis, or complex dislocations, but it can significantly reduce quadriceps strength and may lead to functional issues such as an inability to fully straighten the leg [1] .

3. Anatomy The patella, or kneecap, is the small, floating, sesamoid bone that is located at the front of the knee. The patella is one of three bones, along with the tibia (shin bone) and femur (thigh bone), that make up the knee joint. The patella is embedded inside the quadriceps tendon which connects the quadriceps muscle of the thigh to the shin bone (tibia) below the knee joint. The patella acts as a pulley for the quadriceps and helps create more power during movements of the knee.

4. Biomechanics The patella undergoes approximately 7 cm of translation from full flexion to extension Only 13-38% of the patellar surface is in contact with the femur throughout its range of motion The Patella increases the moment arm about the knee Contributes up to 30% improvement in lever arm

5. Patella withstands compressive forces greater than 7x body weight with squatting 2x Torque: The effective torque at the knee joint (due to quadriceps + patella mechanism) becomes twice as large in the final 15° of extension compared to torque when the knee is in a more flexed position.

6. Patella Fracture Patella fractures are caused by direct trauma or compressive force, or as the indirect result of quadriceps contractions or excessive stress to the extensor mechanism. Indirect injuries are commonly associated with tears of the retinaculum and quadriceps muscles.

7. Etiology Direct Trauma Direct blow to flexed knee Comminution & articular marginal impaction Indirect trauma Flexion force directed through the extensor mechanism against a contracted quadriceps Simple, transverse fracture

8. Types of fractures Patella fractures are classified as either displaced or non-displaced. Displaced fractures are unstable and can be further classified as: Comminuted: As a result of direct trauma (mostly due to blows or falls on flexed knee) Can cause damage to the articular cartilage of patella and femoral condyles. Marginal: As a result of a fall on the knee Vertical/longitudinal Lower/upper pole

9. Types of fractures Transverse/stellate: As a result of muscle contraction/extensive stress on the extensor mechanism, e.g. explosive quadriceps contraction after jumping from height. Most common type Proximal blood supply may be compromised Usually as a result of hyper-flexion of the knee Osteochondral Sleeve (only in pediatric patients)

10. Radiographic Evaluation AP View: Patella height (High or Low) Fracture Pattern Lateral View: Undisplaced - <2 mm separation Displaced - >2 mm separation, step deformity noted Axial or Sunrise

11. Radiographic Evaluation CT Scan Occult fractures Complex or Marginal Impaction Fractures MRI: Diagnosis of associated injuries to nearby tendons and ligaments

12. AP view Lateral view

13. Complications Injuries (sprain/rupture) to ligaments and tendons attached to the patella Avascular necrosis Post-traumatic arthritis Osteochondral damage to patellofemoral joint Stiffness Non-union Malunion

14. Complications Concomitant injuries (e.g. injuries to the acetabulum, femur and tibia) Long term complications: Stiffness Extension weakness Patellofemoral arthritis.

15. Medical Management In acute cases, local anesthetics can be given to eliminate pain. This helps to aid in the assessment and diagnosis of the patella fracture.

16. Conservative Management Indication: Nondisplaced fracture (mostly vertical, horizontal and comminuted fractures) with extensor mechanism in place. Management: Fracture immobilized with POP cylinder cast or range of motion brace locked in extension (4-6 weeks) As healing takes place, knee flexion can gradually be increased Range of motion brace must be worn until union (on X-rays) and clinical signs of healing (not tender on palpation) are present

17. Surgical Interventions Indication: Significant displacement with extensor mechanism not intact or articular step off >2-3mm or fracture displacement >1-4 mm. Management: Transverse/simple, comminuted mid-patella fracture: Open reduction and internal fixation (ORIF) using tension band wire technique using pins and wires and 'a figure of eight' to press the pieces together POP cast in extension for 6 weeks

18. Surgical Interventions Longitudinal (uncommon): Interfragmentary screw fixation Comminuted fracture/irreducible or irreparable fracture or when cartilage too badly damaged: Partial vs complete patellectomy Quadriceps muscles is attached to the patellar ligament to ensure function of the extensor apparatus during a complete patellectomy

19. Patellectomy During a patellectomy, an incision is made into the quadriceps tendon and the patella is freed and removed. With this procedure, the patella tendon remains intact and partially functional. However, the removal of the patella can cause a number of functional problems including; Extension lag :  the reduction in ability to straighten the leg fully Increased laxity:  the loss of the patella leaves the quadriceps tendon lax, and the knee prone to dislocation

20. Vulnerable femoral joint surface:  without the protection of the bony patella, the important cartilage covering the end of the femur is easily damaged by knocks and falls Knee replacement limitations:  knee replacement is problematic after patellectomy. Patellectomy is performed when all the alternative options are not possible, as the patient may be left with weak and poor extension (leg straightening), and the lack of the patella may cause problems when a total knee replacement is considered [2] .

21. Types of patellectomy Complete patellectomy:  The entire patella is removed. Partial patellectomy:  Only a portion of the patella is removed. 

22. Partial Patellectomy Indicated for fractures involving extensive comminution not amenable to fixation Larger fragments repaired with screws to preserve maximum cartilage Smaller fragments excised Tendon is attached to fragment with nonabsorbable suture passed through drill holes in the fragment Load sharing wire passed through the drill holes in the tibial tubercle and patella may be used to protect the repair and facilitate early ROM

23. Total Patellectomy Indicated for displaced, comminuted fractures not amenable for reconstruction Bone fragments sharply dissected Defect may be repaired through a variety of techniques

24. Indications Patellar fractures Advanced chondromalacia Recurrent Dislocations Osteoarthritis of knee Patellar osteomyelitis Rheumatoid arthritis Patellar tumor

25. Complications Knee Stiffness (Most common complication) Infection (Rare, depends on soft tissue compromise) Loss of Fixation (Hardware failure in up to 20% of cases) Osteoarthritis (May result from articular damage or incongruity) Non-union <1% with surgical repair Mal-union Painful hardware (Removal required in approximately 15%)

26. Rehabilitation Protocol Phase 1: Initial Postoperative Phase (Week 1-2) Reduce Swelling and Inflammation: Focus on RICE protocol (Rest, Ice, Compression, Elevation) & compression bandages to manage swelling. Begin gentle range of motion exercises to prevent stiffness.

27. Phase 2: Early Rehabilitation Phase (Week 2-6) Gradual Weight-Bearing Progression: ( knee immobilizer is mandatory) Gradually transition from non-weight-bearing to partial weight-bearing using assistive devices. Start with assisted standing and walking exercises. Improve Range of Motion and Flexibility: Continue with range of motion exercises, incorporating passive stretching as tolerated. Utilize continuous passive motion (CPM) machines if recommended.

28. Strengthening the Quadriceps: Begin isometric quadriceps contractions to initiate muscle activation. Progress to active-assisted and active quadriceps strengthening exercises. Balance and Proprioception Training: Engage in static balance exercises (e.g., standing on one leg) with support. Perform proprioception drills using balance boards or foam pads.

29. Phase 3: Intermediate Rehabilitation Phase (Week 6-12) Full Weight-Bearing and Gait Training: Transition to full weight-bearing activities as the knee becomes more stable. Implement gait training to establish a more natural walking pattern. Advanced Quadriceps Strengthening: Incorporate resistance training exercises like leg presses and squats. Focus on improving quadriceps endurance and strength.

30. Functional Activities: Introduce functional exercises to simulate daily tasks (e.g., stairs, sit-to stand). Emphasize proper form and mechanics during activities.

31. Phase 4: Advanced Rehabilitation Phase (Week 12 and beyond) Full Range of Motion: Work towards achieving full knee flexion and extension for optimal function. Continue with stretching exercises to maintain flexibility. Advanced Balance and Coordination: Progress to more challenging balance exercises and agility drills. Focus on dynamic movements to enhance coordination.

32. Sports-Specific or Activity-Specific Training (if applicable): Tailor the rehab program to the individual’s sports or activity goals. Gradually reintroduce specific movements and activities. Continued Strength and Conditioning: Maintain a regular strength and conditioning program to sustain progress. Continue monitoring and adjusting the program based on individual needs.

33. Reference Günal, I., & Karatosun , V. (2001). Patellectomy: an overview with reconstructive procedures. Clinical orthopaedics and related research, (389), 74–78. https://doi.org/10.1097/00003086-200108000-00012 https://www.physio.co.uk/what-we-treat/surgery/knee/patellectomy.php Textbook of orthopedics 4th edition-2010 by John Ebnezar . Patellectomy: An Overview With Reconstructive Procedures Clinical Orthopaedics and Related Research 389: p 74-78, August 2001. Clinical orthopedic rehabilitation, S.Brent Brotzman, Robert C. Manske. 3rd edition