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Patellar Tendon Repair

Comprehensive surgical technique guide for acute patellar tendon repair with anatomy, technique, augmentation options, and viva scenarios for FRCS exam preparation

Core Procedure
intermediate
By OrthoVellum Medical Education Team

Reviewed by OrthoVellum Editorial Team

Editorial maintenance, source checking, and correction workflow • Published by OrthoVellum Medical Education Team

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High-yield overview

Midline anterior knee approach | intermediate

Mnemonic

J-U-M-PJUMP - Risk Factors for Patellar Tendon Rupture

Hook:Young male athletes with jumpers knee history most common - contrast with quadriceps (older, comorbidities)

Mnemonic

P-A-T-C-HPATCH - Steps of Patellar Tendon Repair

Hook:AUGMENTATION is the key difference from quadriceps repair - almost always needed

Critical Danger Structures

Danger 1

Patellar fracture. Risk during tunnel drilling - use small drill bits, avoid multiple passes, drill eccentrically if osteopenic bone.

Danger 2

Infrapatellar nerve (IPBSN). Saphenous nerve branch at risk with medial incision extension - causes anterior knee numbness.

Danger 3

Patella baja. Over-tensioning creates patellofemoral pain/stiffness - verify height with fluoro against contralateral.

Danger 4

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)

Surgical Anatomy

Patellar Tendon Anatomy

Critical Yield Data
4-5cmTendon length
3cmWidth at insertion
1.0Insall-Salvati ratio
30°Tension angle

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

Clinical Pearl

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)

RatioInterpretation
1.0Normal
>1.2Patella alta (tendon too long or high-riding patella)
<0.8Patella baja (tendon too short or low-riding patella)

Positioning and Preparation

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

Operative Technique

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).

Clinical Pearl

Technical Tip: Midline incision preserves future surgical options (TKA). Avoid extensive medial dissection to protect infrapatellar branch of saphenous nerve.

Danger at this step

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).

Clinical Pearl

Technical Tip: If bone fragment present with tendon, can be repaired with suture or separate fixation. Good bone provides secure anchor point.

Danger at this step

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.

Clinical Pearl

Technical Tip: Gentle debridement only - excessive debridement shortens tendon and creates patella baja. The hematoma contains growth factors - don't wash out completely.

Danger at this step

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.

Clinical Pearl

Technical Tip: Krackow suture technique provides superior pull-out strength compared to simple or Bunnel stitches. Each locking throw increases resistance to slippage.

Danger at this step

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.

Clinical Pearl

Technical Tip: Transosseous tunnel repair is the traditional reference standard. Suture anchors are a valid alternative: cadaveric and pooled biomechanical data show suture anchors give EQUIVALENT ultimate load to failure and LESS cyclic gap formation than transosseous sutures (Imbergamo 2022; Ettinger/Petri 2013) - so the old teaching that anchors are "weaker" is outdated. Choose based on bone quality and familiarity; in osteoporotic bone, augmentation matters more than the tunnel-vs-anchor choice.

Danger at this step

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.

Clinical Pearl

Technical Tip: Keep sutures organized (medial, central, lateral) to ensure even tension distribution across tendon width during final tensioning.

Danger at this step

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.

Clinical Pearl

Technical Tip: ALWAYS compare to contralateral side with lateral x-ray. Under-tensioning = patella alta (weak extension), over-tensioning = patella baja (stiffness, patellofemoral pain).

Danger at this step

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.

Clinical Pearl

Technical Tip: Tying at 30 degrees protects repair during early ROM. Tying in full extension risks over-tensioning when knee flexes.

Danger at this step

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

Clinical Pearl

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).

Danger at this step

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.

Clinical Pearl

Technical Tip: Always repair retinacular tears - they contribute to extensor function. Document final patellar height radiographically.

Danger at this step

Missing retinacular tears that contribute to extensor lag

Chronic Patellar Tendon Rupture

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

Clinical Pearl

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.

Complications

Complications: Recognition, Prevention, and Management

Post-operative Care

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

Clinical Decision Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"A 28-year-old male basketball player presents to ED after landing awkwardly from a jump. He felt a pop in his knee and cannot straighten it. On examination there is a palpable defect below the patella and he cannot perform SLR. X-ray shows patella alta. How would you manage this patient?"

PRACTICAL APPROACH
This is a classic presentation of acute patellar tendon rupture. My management approach would be: **Immediate Assessment:** - Confirm clinical findings: palpable gap at inferior pole, high-riding patella, inability to SLR - Document neurovascular status - Lateral x-ray confirms patella alta (elevated Insall-Salvati ratio >1.2) - Check for avulsion fragment at inferior pole **Pre-operative Planning:** - Obtain lateral x-ray of contralateral knee for patellar height comparison - MRI not required for acute complete rupture with clear clinical picture - Discuss with patient: acute repair has best outcomes, requires augmentation, rehabilitation 4-6 months **Surgical Technique:** 1. Midline incision, identify both tendon stumps 2. Gentle debridement of frayed ends 3. Krackow locking sutures (#5 FiberWire) through distal stump 4. 2-3 transosseous tunnels in inferior pole patella 5. Restore patellar height to match contralateral side (Insall-Salvati = 1.0) 6. Tie sutures with knee at 30 degrees flexion 7. AUGMENTATION with suture tape (FiberTape through patella and tibial tubercle) 8. Repair retinacular tears 9. Document final patellar height on lateral x-ray **Post-operative:** - Hinged brace locked in extension 2 weeks - Progressive ROM 0-90 degrees by 6 weeks - Expect return to basketball 6-9 months
CLINICAL SCENARIOStandard

CLINICAL PROMPT

"During patellar tendon repair, you are tensioning the repair and notice the patella appears lower than the contralateral side on lateral x-ray. What is the concern and how do you address it?"

PRACTICAL APPROACH
This is PATELLA BAJA (low-riding patella) - a significant intraoperative finding that must be corrected before completing the repair. **Concerns with Patella Baja:** 1. Patellofemoral pain - patella articulates with trochlea in flexion where it shouldn't 2. Knee stiffness - mechanical block to full flexion 3. Quadriceps weakness - altered moment arm 4. Difficult to correct secondarily - requires tendon lengthening **Causes:** - Over-tensioning the repair - Excessive tendon debridement (shortened tendon) - Tying sutures with knee in extension **Management:** 1. Stop and reassess before tying final knots 2. Release some tension from repair sutures 3. Reposition knee to 30 degrees flexion (relaxes quadriceps) 4. Re-check lateral x-ray to confirm correct height 5. Compare to contralateral Insall-Salvati ratio (target = 1.0) 6. May need to accept slightly loose repair rather than over-tension **Prevention Strategies:** - Always compare to contralateral side intraoperatively - Tie sutures with knee at 30 degrees, NOT in extension - Minimize tendon debridement - Check height BEFORE applying augmentation
CLINICAL SCENARIOStandard

CLINICAL PROMPT

"A 52-year-old diabetic woman on long-term steroids for rheumatoid arthritis presents with patellar tendon rupture. How does her medical history influence your surgical approach?"

PRACTICAL APPROACH
This patient has multiple risk factors for tendon rupture AND poor healing, which significantly influences my surgical approach. **Risk Factor Analysis:** - **Steroids**: Tendon weakening, impaired healing, increased re-rupture risk - **Rheumatoid arthritis**: Systemic tendon pathology, poor tissue quality - **Diabetes**: Microangiopathy, impaired wound/tendon healing - **Age 52**: Older than typical patellar tendon rupture (usually <40) **Implications for Surgery:** **1. Tissue Quality:** - Expect degenerated, friable tendon tissue - May not hold sutures well - Higher risk of pull-out failure **2. Fixation Strategy:** - Use MULTIPLE transosseous tunnels (4-5 rather than 2-3) - Consider suture anchors as backup - Heavy augmentation ESSENTIAL - May need reconstruction with allograft if tissue inadequate **3. Augmentation:** - MORE augmentation than standard case - Consider double augmentation (tape + wire) or - Consider autograft augmentation (semitendinosus) primarily **4. Peri-operative:** - Optimize diabetes (HbA1c) - Discuss steroid dose with rheumatologist (may need stress dose) - Extended antibiotic prophylaxis - Higher infection risk - meticulous technique **5. Post-operative:** - Slower rehabilitation progression - Longer immobilization (brace 4-6 weeks rather than 2) - Delayed ROM progression - Extended augmentation retention (6-12 months) **Counselling:** - Higher re-rupture risk despite augmentation - May need revision surgery - Prolonged recovery expected

Patellar Tendon Repair - Exam Summary

Clinical summary

Evidence Base

Acute and old ruptures of the extensor apparatus of the knee in adults (excluding knee replacement)

Level III
Saragaglia D, Pison A, Rubens-Duval B • Orthopaedics and Traumatology: Surgery and Research (OTSR)
Clinical Implication: Establishes the core demographic distinction and the principle that augmentation-protected repair is standard for acute tears, while chronic tears need reconstruction.
Verify on PubMed (PMID 23352566)

Failure Rates of Suture Anchor Fixation Versus Transosseous Tunnel Technique for Patellar Tendon Repair: A Systematic Review and Meta-analysis of Biomechanical Studies

Level IV
Imbergamo C, Sequeira S, Bano J, Rate WR, Gould H • Orthopaedic Journal of Sports Medicine
Clinical Implication: Refutes the dogma that transosseous tunnels are intrinsically stronger; suture anchors are a biomechanically equivalent (lower-gap) alternative, so technique choice can be guided by bone quality and surgeon familiarity.
Verify on PubMed (PMID 36035892)

Biomechanical properties of suture anchor repair compared with transosseous sutures in patellar tendon ruptures: a cadaveric study

Level II
Ettinger M, Dratzidis A, Hurschler C, Brand S, Calliess T, Krettek C, Jagodzinski M, Petri M • The American Journal of Sports Medicine
Clinical Implication: Supports suture anchors as a robust fixation option; the Krackow whipstitch remains the key tendon-grasping technique regardless of bone-side fixation.
Verify on PubMed (PMID 23982397)

Patellar tendon restoration techniques: a systematic review of outcomes for repair and reconstruction methods

Level IV
Fortier LM, Adelstein JM, Sinkler MA, Moyal AJ, Burkhart RJ, Vakharia AM, Dasari SP, Chahla J • European Journal of Orthopaedic Surgery and Traumatology
Clinical Implication: When augmenting, favour flexible suture-tape constructs over rigid cerclage wire; reserve allograft reconstruction for post-TKA and chronic retracted ruptures.
Verify on PubMed (PMID 39212690)

Comparison of adverse events and postoperative mobilization following knee extensor mechanism rupture repair: A systematic review and network meta-analysis

Level III
Serino J, Mohamadi A, Orman S, McCormick B, Hanna P, Weaver MJ, Harris MB, Nazarian A, von Keudell A • Injury
Clinical Implication: Rehabilitation must balance stiffness against re-rupture; aggressive early flexion without robust augmentation raises complications, justifying protected progressive ROM.
Verify on PubMed (PMID 29050687)

Guidelines, Registries and Global Practice

There is no single national-society guideline dedicated to patellar tendon repair; practice is driven by Level III-IV evidence and biomechanical studies that are consistent worldwide. Key points of global consensus and where practice genuinely varies:

QuestionGlobal consensusWhere practice differs
TimingAcute complete ruptures repaired early (ideally within 2 weeks) - uniform across AAOS, BOA, AO Foundation teachingSubacute window tolerance (2-6 weeks) varies by surgeon and tissue quality
Bone-side fixationTransosseous tunnels OR suture anchors both acceptable; biomechanically equivalentNorth American/European sports units increasingly favour suture anchors and suture-tape internal bracing; transosseous remains common globally and in resource-limited settings
AugmentationAugmentation protects the repair and lowers re-ruptureFlexible suture tape now preferred over cerclage wire where available; cerclage/wire still widely used where suture-tape implants are cost-prohibitive
RehabilitationProtected progressive ROM in a hinged braceTrend toward earlier ROM in well-augmented constructs, balanced against meta-analysis evidence (Serino 2017) that early mobilization raises adverse events

Resource-setting note: transosseous tunnel repair with heavy non-absorbable suture and a stainless-steel cerclage/Mersilene-tape frame remains an entirely valid, low-cost technique with comparable mechanical resistance, important for global practice where proprietary suture-anchor and suture-tape implants are unavailable.

References

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  2. Enad JG. Patellar tendon repairs. J South Orthop Assoc. 1999;8(1):20-24.

  3. Bhargava SP, Hynes MC, Dowell JK. Traumatic patella tendon rupture: early mobilisation following surgical repair. Injury. 2004;35(11):1158-1160.

  4. Ramseier LE, Werner CM, Heinzelmann M. Quadriceps and patellar tendon rupture. Injury. 2006;37(6):516-519.

  5. Matava MJ. Patellar tendon ruptures. J Am Acad Orthop Surg. 1996;4(6):287-296.

  6. Greis PE, Holmstrom MC, Lahav A. Surgical treatment options for patella tendon rupture, Part I: Acute. Orthopedics. 2005;28(7):672-679.

  7. Cree C, Pillai A, Jones B, Blyth M. Bilateral patellar tendon ruptures: A missed diagnosis. Knee Surg Sports Traumatol Arthrosc. 2007;15(11):1350-1354.

  8. West JL, Keene JS, Kaplan LD. Early motion after quadriceps and patellar tendon repairs: outcomes with single-suture augmentation. Am J Sports Med. 2008;36(2):316-323.

  9. Rougraff BT, Reeck CC, Essenmacher J. Complete quadriceps tendon ruptures. Orthopedics. 1996;19(6):509-514.

  10. Camarda L, Giannice G, Lauria M, Minacapelli A, D'Arienzo M. Surgical treatment of acute patellar tendon rupture with suture anchors. Muscles Ligaments Tendons J. 2017;7(2):294-299.

  11. Imbergamo C, Sequeira S, Bano J, Rate WR, Gould H. Failure Rates of Suture Anchor Fixation Versus Transosseous Tunnel Technique for Patellar Tendon Repair: A Systematic Review and Meta-analysis of Biomechanical Studies. Orthop J Sports Med. 2022;10(8):23259671221120212. PMID: 36035892. doi:10.1177/23259671221120212.

  12. Ettinger M, Dratzidis A, Hurschler C, Brand S, Calliess T, Krettek C, Jagodzinski M, Petri M. Biomechanical properties of suture anchor repair compared with transosseous sutures in patellar tendon ruptures: a cadaveric study. Am J Sports Med. 2013;41(11):2540-2544. PMID: 23982397. doi:10.1177/0363546513500633.

  13. Fortier LM, Adelstein JM, Sinkler MA, et al. Patellar tendon restoration techniques: a systematic review of outcomes for repair and reconstruction methods. Eur J Orthop Surg Traumatol. 2024;34(8):3827-3845. PMID: 39212690. doi:10.1007/s00590-024-04078-3.

  14. Serino J, Mohamadi A, Orman S, et al. Comparison of adverse events and postoperative mobilization following knee extensor mechanism rupture repair: A systematic review and network meta-analysis. Injury. 2017;48(12):2793-2799. PMID: 29050687. doi:10.1016/j.injury.2017.10.013.

  15. Bushnell BD, Tennant JN, Rubright JH, Creighton RA. Repair of patellar tendon rupture using suture anchors. J Knee Surg. 2008;21(2):122-129. PMID: 18500063. doi:10.1055/s-0030-1247806.