Patellar fractures account for approximately 1% of all skeletal injuries, yet carry high functional significance because the patella serves as the primary fulcrum of the knee extensor mechanism. Displaced or comminuted fractures disrupt active extension, compromise joint congruency, and risk accelerated patellofemoral osteoarthritis if anatomical reduction is not achieved.
Etiology and Injury Mechanisms
- Direct Trauma (Most Common): Direct impact from falls onto a flexed knee, motor vehicle collisions (“dashboard injury”), or blunt sports contact. These frequently result in comminuted or stellate patterns.
- Indirect Trauma: Forceful eccentric contraction of the quadriceps muscle during sudden deceleration or stumbling, typically causing transverse fracture patterns with retinacular rupture.
Clinical Signs and Diagnostic Criteria
- Physical Findings: Acute anterior knee pain, rapid tense hemarthrosis, focal tenderness, palpable bony gap, and an inability to perform an active straight leg raise (extensor mechanism failure).
- Radiographic Evaluation: AP, lateral, and axial (sunrise) radiographs assess fracture morphology, displacement, and joint step-off. A lateral view accurately quantifies articular incongruity.
Management Approaches
| Fracture Type | Clinical Criteria | Management Strategy | Union Rate |
| Non-Displaced | $<2\text{ mm}$ displacement, $<2\text{ mm}$ step-off, intact extensor mechanism | Cylinder cast / hinged brace locked at $0^\circ$ for 4–6 weeks | 80–90% |
| Transverse Displaced | $\ge 2\text{ mm}$ displacement, disrupted extensor mechanism | Modified tension band wiring (TBW) or cannulated screws | 85–92% |
| Comminuted (Reconstructable) | Multi-fragmentary with preserved poles | Low-profile anatomical locking plates / TBW | 80–88% |
| Severely Comminuted Pole | Unreconstructable inferior/superior pole | Partial patellectomy + direct tendon re-anchoring | 75–85% |
Surgical Techniques
- Modified Tension Band Wiring (TBW): The classic mechanical technique utilizing two parallel longitudinal Kirschner wires (or cannulated screws) and a figure-of-eight stainless steel wire loop to convert anterior tension forces during flexion into compressive forces across the articular surface.
- Cannulated Screws with Tension Band: Combines rigid interfragmentary screw compression with dynamic wire tensioning, allowing earlier functional rehabilitation.
- Anatomical Plate Fixation: Multi-planar locking plates provide stable multi-point fixation for osteoporotic bone or complex comminution.
- Partial Patellectomy: Indicated when pole comminution prevents stable osteosynthesis. The small non-viable fragments are excised, and the patellar or quadriceps tendon is reattached directly to the remaining patellar body using transosseous sutures.
Postoperative Rehabilitation Milestones
- Weeks 0–6 (Protection & Initial Healing): Protected partial weight-bearing with crutches and a hinged knee brace locked at $0^\circ$ extension. Early passive ROM ($0^\circ\text{–}30^\circ$, progressing incrementally) and isometric quadriceps sets are initiated.
- Weeks 6–8 (Consolidation): Radiographic confirmation of bony union, active-assisted range of motion, brace weaning, and unassisted physiological gait retraining.
- Months 3–4: Stationary cycling, swimming, and closed-chain quadriceps strengthening. Resumption of sedentary/desk work occurs by weeks 3–4.
- Months 4–6: Straight-line jogging and functional return-to-sport testing once full range of motion and $\ge 85\text{–}90\%$ muscular symmetry are achieved.
Complications and Hardware Removal
Primary complications include symptomatic hardware prominence (30–50% due to thin subcutaneous tissue over the patella, often necessitating elective removal after 6–12 months of solid union), post-traumatic patellofemoral arthritis (15–25%), knee stiffness (5–15%), and non-union ($<3\%$). Early anatomical restoration and structured physical therapy minimize long-term extensor weakness and articular degeneration.
Frequently Asked Questions: Quadriceps Tendon Repair Surgery
What is quadriceps tendon repair surgery and how is it performed?
Quadriceps tendon repair is an open surgical procedure designed to re-establish the anatomical connection between the ruptured quadriceps tendon and the superior pole of the patella. Through an anterior midline knee incision, the ruptured tendon edges are refreshed, and strong non-absorbable locking sutures (such as #2 FiberWire) are placed in a Krackow or Kessler configuration. The sutures are then anchored firmly into the patella to re-tension and restore the extensor mechanism of the knee.
What are the primary clinical indications for quadriceps tendon repair?
Surgical intervention is indicated in the following scenarios:
- Acute Complete Ruptures: Total loss of the knee extensor mechanism and inability to perform an active straight leg raise.
- Significant Partial Tears: Tears involving more than 50% of the tendon width associated with an extensor lag (>15°–20°) that fail conservative immobilization.
- Retinacular Disruption: Concomitant tears of the medial and lateral retinacula causing joint instability.
- Chronic/Neglected Ruptures: Persistent gait abnormalities, knee buckling, and functional disability.
How does the transosseous tunnel technique compare to suture anchor fixation?
Both methods provide excellent clinical outcomes, but they differ in technical execution:
- Transosseous Tunnels: The traditional standard involving three longitudinal drill tunnels through the patella, exiting at the inferior pole where sutures are tied over a bone bridge. It is cost-effective and dependable.
- Suture Anchors: Involves inserting 2 to 4 bio-composite or titanium suture anchors into the superior patellar footprint. This approach reduces operative time, avoids full-thickness patellar drilling, and minimizes the risk of iatrogenic patellar fractures while providing equal load-to-failure strength.
Why is early surgical intervention (within 2–3 weeks) strongly recommended?
Primary surgical repair is optimal within the first 14 to 21 days post-injury. During this window, the tendon maintains adequate elasticity and tissue quality for direct bone-to-tendon opposition. Beyond 3 to 4 weeks, the proximal quadriceps muscle retracts and undergoes fatty atrophy, while dense scar tissue forms, frequently requiring complex lengthening plasties or tissue augmentation.
How are chronic or neglected quadriceps tendon tears surgically managed?
When primary direct repair is not feasible due to severe tendon retraction, surgeons utilize specialized reconstructive procedures:
- Codivilla V-Y Lengthening: An inverted V-plasty performed in the proximal quadriceps tendon to mobilize and advance the tendon distally.
- Scuderi Turndown Flap: A partial-thickness triangular flap turned down from the proximal tendon to bridge and reinforce the repair site.
- Tissue Augmentation: Incorporating autologous semitendinosus/gracilis tendons, synthetic mesh, or human allografts (Achilles tendon or fascia lata) to bridge large structural gaps.
What type of anesthesia is used, and what is the typical duration of the surgery?
The surgery is conducted under regional spinal anesthesia or general anesthesia, routinely augmented by a peripheral regional nerve block (e.g., adductor canal block) for effective postoperative analgesia. In acute cases, the operative time generally ranges between 45 and 75 minutes, while chronic reconstructions may take 90 to 120 minutes.
What are the expected clinical outcomes and success rates after surgery?
Acute primary repair achieves clinical success rates of 90% to 95%. Validated outcome measures demonstrate excellent patient satisfaction, full restoration of active knee extension, and return to pre-injury daily activities. Most patients regain within 5° to 10° of contralateral flexion, with quadriceps strength recovering to 80%–90% of the uninjured leg after structured rehabilitation.
What are the potential complications of quadriceps tendon repair surgery?
Complications occur in fewer than 3% to 6% of cases and include:
- Joint Stiffness (Arthrofibrosis): Loss of flexion, mitigated by early progressive passive range of motion.
- Tendon Re-Rupture: Rare (<2%–4%), typically resulting from accidental falls or premature unbraced weight-bearing during the first 6 weeks.
- Extensor Lag: Persistent inability to fully extend the knee actively due to residual quadriceps atrophy or loose repair tensioning.
- Infection and DVT: Prevented through perioperative antibiotics and routine thromboprophylaxis.
What is the standard postoperative rehabilitation and weight-bearing protocol?
The postoperative rehabilitation is phased to protect the repair during biological bone-tendon healing:
- Weeks 0–6: Weight-bearing as tolerated with crutches in a hinged knee brace locked at 0° extension; passive flexion is increased incrementally under physical therapy guidance (0°–30° for weeks 1–2, 0°–60° for weeks 3–4, up to 90° by week 6).
- Weeks 6–12: Weaning off crutches, unlocking the brace for ambulation, and initiating active knee extension and closed-chain kinetic strengthening.
- Months 3–6: Progressive resistance exercises, proprioceptive training, and functional conditioning.
When can patients return to driving, work, and athletic activities?
Milestones for functional recovery include:
- Sedentary / Desk Work: 3 to 4 weeks (with periodic limb elevation).
- Driving: 6 to 8 weeks for right-knee procedures (once brace-free ambulation and rapid emergency braking control are established).
- Low-Impact Training (Stationary Bike, Swimming): 3 to 4 months.
- High-Demand Sports & Heavy Labor: 6 to 9 months, following objective limb symmetry index (>85%–90%) clearance on dynamometer testing.