import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Patellar fracture**. Risk during tunnel drilling - use small drill bits, avoid multiple passes, drill eccentrically if osteopenic bone. **Infrapatellar nerve (IPBSN)**. Saphenous nerve branch at risk with medial incision extension - causes anterior knee numbness. **Patella baja**. Over-tensioning creates patellofemoral pain/stiffness - verify height with fluoro against contralateral. **Patella alta**. Under-tensioning leads to weak repair, persistent extensor lag - increases re-rupture risk. ### Indications for Patellar Tendon Repair **Absolute Indications:** - Complete patellar tendon rupture with loss of active knee extension - Palpable gap at inferior pole with high-riding patella - Inability to perform straight leg raise **Relative Indications:** - Partial rupture (>50%) with significant extensor weakness - Chronic rupture with functional limitation - Re-rupture after previous repair **Timing:** - Acute repair (<2 weeks): Primary repair with augmentation - Subacute (2-6 weeks): May still achieve primary repair - Chronic (>6 weeks): Often requires reconstruction (allograft/autograft) ### Contraindications **Absolute:** - Active infection at surgical site - Non-functional knee (pre-existing severe arthritis, neurological deficit) - Medical contraindication to surgery **Relative:** - Severe peripheral vascular disease - Uncontrolled diabetes - Active malignancy requiring urgent treatment - Non-ambulatory patient with minimal functional demand **Special Considerations:** - Steroid use: increased re-rupture risk, consider augmentation essential - CKD/dialysis patients: compromised tissue, augment heavily - Post-TKA rupture: may need component revision for access ### Pre-operative Assessment **Clinical Examination:** - Palpable defect at inferior pole patella - High-riding patella (patella alta) - Inability to straight leg raise (SLR) - Suprapatellar hematoma/swelling - Test for associated injuries (bone avulsion, retinacular tears) **Imaging:** - **X-ray lateral**: Confirms patella alta (Insall-Salvati >1.2) - May show avulsion fragment at inferior pole - **Contralateral lateral**: For patellar height comparison - **MRI**: Defines rupture location, retraction, tissue quality - Useful for partial ruptures **Consent Discussion:** - 80-95% return to pre-injury activity level with augmented repair - Re-rupture rate 2-5% with augmentation vs 15-20% without - Knee stiffness most common complication - May need hardware removal (cerclage wire) ### Required Equipment **Basic Setup:** - Knee arthroscopy set (backup for joint assessment) - Standard orthopaedic soft tissue tray - Tourniquet - Image intensifier for patellar height assessment **Specific Instruments:** - Heavy non-absorbable suture (#2 or #5 Ethibond, FiberWire) - Suture anchor set (if used for fixation) - 2.0mm and 2.5mm drill bits for transosseous tunnels - Large curved needle for Krackow sutures - Suture tape augmentation system (e.g., Internal Brace) **Optional:** - Cerclage wire (1.2-1.6mm) if wire augmentation preferred - Tendon graft (semitendinosus) for chronic cases **Positioning:** - Supine, bump under knee - Contralateral leg accessible for height comparison - Prep both knees for comparison x-ray ### Patellar Tendon Anatomy **Tendon Structure:** - Continuation of quadriceps tendon, passing over patella - Originates from inferior pole of patella - Inserts onto tibial tubercle - 3-5mm thick, 3cm wide at insertion **Blood Supply:** - Inferior pole: branches from inferior genicular vessels - Tibial insertion: recurrent tibial vessels - **Watershed area**: mid-substance relatively avascular **Rupture Locations:** 1. **Inferior pole patella** (80%) - bone-tendon junction most common 2. **Mid-substance** (10%) - associated with tendinopathy 3. **Tibial tubercle avulsion** (10%) - especially adolescents **EXAM KEY**: Patellar tendon ruptures occur at bone-tendon junction (inferior pole) in 80% of cases. Mid-substance ruptures suggest underlying tendinopathy (jumpers knee). Always examine for avulsion fragments. ### Insall-Salvati Ratio **Definition**: Patellar tendon length / Patella length (measured on true lateral x-ray) | Ratio | Interpretation | |-------|----------------| | 1.0 | Normal | | >1.2 | Patella alta (tendon too long or high-riding patella) | | <0.8 | Patella baja (tendon too short or low-riding patella) | **Patient Position**: - Supine on radiolucent table - Tourniquet on proximal thigh (250-300mmHg) - Bump under knee to maintain slight flexion - **CRITICAL**: Contralateral leg accessible and prepped for comparison x-rays **Surface Markings:** - Patella borders (superior, inferior, medial, lateral) - Tibial tubercle - Palpable defect at rupture site - Mark planned incision **Preparation:** - Prep both knees from mid-thigh to mid-leg - Ensure C-arm can obtain true lateral of BOTH knees - Betadine paint and drape **Anaesthesia:** - General or spinal anaesthesia - Consider nerve block for postoperative analgesia ### Step 1: Incision and Exposure Make midline longitudinal incision from inferior pole of patella to tibial tubercle (8-10cm). Develop full-thickness skin flaps. Identify the high-riding patella (pathognomonic for complete rupture). **Technical Tip**: Midline incision preserves future surgical options (TKA). Avoid extensive medial dissection to protect infrapatellar branch of saphenous nerve. Infrapatellar nerve injury medially - causes anterior knee numbness ### Step 2: Identify Tendon Stumps and Assess Identify proximal tendon stump at inferior pole patella and distal stump at tibial tubercle. Assess tendon quality. Check for sleeve fracture (bone fragment attached to tendon). **Technical Tip**: If bone fragment present with tendon, can be repaired with suture or separate fixation. Good bone provides secure anchor point. Missing sleeve fracture - may alter fixation strategy ### Step 3: Debride Tendon Ends Debride frayed, devitalized tissue from both tendon stumps. Create healthy bleeding edges for healing. Do NOT over-debride - preserve tendon length. **Technical Tip**: Gentle debridement only - excessive debridement shortens tendon and creates patella baja. The hematoma contains growth factors - don't wash out completely. Over-debridement leading to shortened tendon and patella baja ### Step 4: Pass Krackow Locking Sutures Pass Krackow locking sutures through distal tendon stump using heavy non-absorbable suture (#2 or #5). Minimum 4 locking passes for secure grip. Can use FiberWire or FiberTape for added strength. **Technical Tip**: Krackow suture technique provides superior pull-out strength compared to simple or Bunnel stitches. Each locking throw increases resistance to slippage. Inadequate suture purchase in degenerated tendon ### Step 5: Create Transosseous Tunnels in Patella Create 2-3 vertical transosseous tunnels in inferior pole of patella using 2.0-2.5mm drill. Tunnels should exit at superior pole of patella. Use gentle technique to avoid fracture. **Technical Tip**: Transosseous repair is STRONGEST fixation method. Alternative is suture anchors at inferior pole - technically easier but less secure. In osteoporotic bone, use more tunnels and protect with augmentation. Patellar fracture from aggressive drilling - use small drill, single pass per tunnel ### Step 6: Pass Sutures Through Tunnels Thread Krackow sutures through transosseous tunnels from inferior to superior pole. Pull tendon to approximate anatomic footprint at inferior pole. **Technical Tip**: Keep sutures organized (medial, central, lateral) to ensure even tension distribution across tendon width during final tensioning. Crossed or tangled sutures causing uneven tension ### Step 7: Restore Patellar Height (CRITICAL) **CRITICAL STEP**: Bring knee to 30 degrees flexion. Tension repair to restore NORMAL PATELLAR HEIGHT. Use lateral fluoroscopy to compare with contralateral knee. Insall-Salvati ratio should equal 1.0. **Technical Tip**: ALWAYS compare to contralateral side with lateral x-ray. Under-tensioning = patella alta (weak extension), over-tensioning = patella baja (stiffness, patellofemoral pain). Patella baja (over-tension) causes stiffness and patellofemoral pain. Patella alta (under-tension) leads to re-rupture. ### Step 8: Tie Sutures with Knee in 30 Degrees Flexion Tie all sutures over superior pole of patella with knee maintained at 30 degrees flexion. Use multiple throws and bury knots. **Technical Tip**: Tying at 30 degrees protects repair during early ROM. Tying in full extension risks over-tensioning when knee flexes. Tying in extension creates excessive tension during flexion ### Step 9: Augmentation (ESSENTIAL) Apply augmentation to protect repair. Options: **A) Suture Tape (Preferred):** - Pass FiberTape through patellar tunnel and tibial tubercle - Tension to limit flexion to 90 degrees initially - Lower profile, no hardware removal needed **B) Cerclage Wire:** - Figure-8 wire from patella to tibial tubercle - 1.2-1.6mm wire - Remove at 3-6 months **Technical Tip**: AUGMENTATION is almost always needed for patellar tendon repair - unlike quadriceps. Re-rupture rate drops from 15-20% to 2-5% with augmentation. Suture tape preferred over wire (fewer complications, no removal). Omitting augmentation - significantly increases re-rupture risk ### Step 10: Final Check and Closure Check active extension - patient should be able to straight leg raise. Confirm patellar height on final lateral x-ray. Repair medial and lateral retinacular tears. Layered closure over drain. **Technical Tip**: Always repair retinacular tears - they contribute to extensor function. Document final patellar height radiographically. Missing retinacular tears that contribute to extensor lag ### Definition and Challenges - Rupture >6 weeks old - Tendon retraction and shortening - Quadriceps adhesions and contracture - May require V-Y lengthening or graft reconstruction ### Reconstruction Options **1. Semitendinosus Autograft:** - Harvest ipsilateral semitendinosus - Route through patellar and tibial tunnels - Augment with remaining native tendon **2. Achilles Allograft:** - Bone block fixed to tibial tubercle - Tendon sutured to patella - Provides length for retracted cases **3. V-Y Lengthening:** - For 2-4cm gaps with retracted quadriceps - Create V-incision in quadriceps, slide distally - Close as Y to gain length **EXAM KEY**: Chronic ruptures often need reconstruction not repair. Key is restoring patellar height and extensor mechanism continuity. Prepare patient for prolonged rehabilitation and possible secondary procedures. ### Immediate Post-operative - Hinged knee brace locked in extension - Neurovascular checks - DVT prophylaxis - Ice and elevation ### Week 0-2 - Brace locked in extension - Weight bearing as tolerated in brace - Passive ROM 0-30 degrees only - Straight leg raise exercises (quad isometrics) ### Week 2-6 - Unlock brace, progress flexion 0-90 degrees - Active assisted ROM exercises - Continue quad strengthening - Pool therapy when wound healed ### Week 6-12 - Discontinue brace when good quad control - Progress to full ROM - Closed chain strengthening - Stationary cycling ### 3-6 Months - Return to light activities - Sport-specific training - Wire removal if used and symptomatic ### 6+ Months - Return to full activity when: - Full ROM achieved - Quad strength >80% contralateral - No pain or instability - Healed on imaging 1. Saragaglia D, Pison A, Rubens-Duval B. 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