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Peroneal Tendon Disorders

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Overview

Exam Detail:

Key Revision Focus: Distinction between Peroneal Tears (usually Brevis) and Subluxation (SPR incompetence). Anatomy of the retromalleolar groove. Surgical techniques (Tubularization vs Tenodesis vs Groove Deepening).

1. Clinical Overview

Peroneal Tendon Disorders encompass a spectrum from tenosynovitis to frank tears (longitudinal splits) and instability (subluxation/dislocation). They are a common cause of persistent lateral ankle pain, often misdiagnosed as "chronic ankle sprains".

Clinical Pearl:

The Brevis Trap: The Peroneus Brevis is the one that tears (longitudinal split) because it lies deep in the groove and gets crushed by the Peroneus Longus ("The Meat Grinder"). The Longus rarely tears but can contain a painful os peroneum.

Key Concepts

  1. Anatomy:
    • Peroneus Longus: Superficial. Inserts on 1st Metatarsal Base (Plantarflexes 1st Ray).
    • Peroneus Brevis: Deep (closest to bone). Inserts on 5th Metatarsal Base (Everts foot).
    • Common Synovial Sheath: Splits deep to the peroneal tubercle.
  2. Superior Peroneal Retinaculum (SPR): The primary restraint preventing subluxation out of the retromalleolar groove.
  3. Mechanism:
    • Tears: chronic attrition or acute inversion injury.
    • Subluxation: Sudden intense Dorsiflexion + Inversion (e.g., skiing, soccer). The SPR snaps off the fibula.
  4. Cavovarus Foot: Predisposes to peroneal pathology (overload of evertors compensating for varus).
  5. Os Peroneum: Accessory bone in P. Longus tendon (at cuboid tunnel). Can fracture or cause "Painful Os Peroneum Syndrome" (POPS).

Clinical Pearls

  • The "Pop": A sensation of popping or snapping over the lateral malleolus is diagnostic of subluxation until proven otherwise.
  • Volleyball Ankle: High prevalence in sports involving jumping/landing on inverted foot.
  • Retromalleolar Pain: Pain behind the fibula is Peroneal. Pain anterior to fibula is ATFL/Ankle Sprain.
  • Hypertrophic Peroneal Tubercle: Can cause attrition of the Longus.

2. Epidemiology

  • Prevalence: 25-30% of patients with chronic ankle instability have peroneus brevis tears.
  • Demographics: Young active patients (subluxation) or middle-aged (tears/tendinopathy).
  • Risk Factors: Cavovarus foot shape, Generalized ligamentous laxity.

3. Pathophysiology

Mechanism of Injury

  • Subluxation: Forced dorsiflexion of an inverted foot leads to rapid contraction of peroneals. The SPR fails (usually strips off the fibular periosteum - Fleck sign).
  • Tears:
    • Mechanical attrition: In the retromalleolar groove.
    • "Meat Grinder" effect: P. Longus compresses P. Brevis against the sharp posterior ridge of the fibula during activity.
    • Devascularization: Watershed area around the turn of the malleolus.

Classification of SPR Injury (Ogen)

  1. Grade I: SPR elevated from fibula (periosteal stripping). Commonest.
  2. Grade II: SPR tears at fibrocartilaginous attachment.
  3. Grade III: Avulsion fracture (Fleck sign).
  4. Grade IV: Tear of SPR midsubstance.

4. Clinical Presentation

  • Pain: Posterior to lateral malleolus. Worse with activity/uneven ground.
  • Instability: Feeling of "giving way" or "snapping".
  • Swelling: Specific "sausage-like" swelling along the tendon sheath (retromalleolar).

5. Clinical Examination

  1. Look:
    • Effusion in sheath.
    • Heel varus (Check alignment). "Peek-a-boo" heel sign.
  2. Feel:
    • Tenderness directly over tendons behind fibula.
    • Palpate 5th Met base (Brevis insertion) and Cuboid tunnel (Longus).
  3. Move:
    • Resisted Eversion: Pain + Weakness suggests tear.
    • Provocation Test for Subluxation:
      • Patient prone, knee at 90°.
      • Ask patient to Dorsiflex and Evert against resistance.
      • Look/Feel for tendons popping out over the fibula.
    • Coleman Block Test: If cavovarus is present, is it hindfoot flexible? (Essential for surgical planning - may need osteotomy).

6. Investigations

X-ray

  • AP/Lateral/Moutise: Usually normal.
  • Fleck Sign: Small avulsion of calcified SPR rim off lateral malleolus (Pathognomonic for dislocation).
  • Os Peroneum: Check position (proximal migration suggests rupture).

Ultrasound

  • Dynamic U/S: The Gold Standard for diagnosing Subluxation. Watch the tendon snap over the bone during movement.
  • Access to groove depth.

MRI

  • Gold Standard for tears.
  • C-Sign: Fluid wrapping around the tendon.
  • Split: Brevis often looks "boomerang" shaped or bifurcated (longitudinal split).
  • Tenomsynovitis: Fluid in sheath.
  • Low Lying Muscle Belly: Anomalous muscle extending into groove (occupies space -> crowding).

7. Management

Management depends on pathology (Tenodesis vs Subluxation vs Tear).

ASCII Algorithm:

          Peroneal Pain / Instability
                      ↓
┌──────────────────────────────────────────────┐
│  DIAGNOSIS (MRI / Dynamic US)                │
├───────────────┬──────────────┬───────────────┤
│ TENOSYNOVITIS │    TEAR      │  SUBLUXATION  │
└───────┬───────┴──────┬───────┴───────┬───────┘
        ↓              ↓               ↓
┌───────────────┐ ┌──────────┐ ┌───────────────┐
│ CONSERVATIVE  │ │ SYMPTOM? │ │    ACUTE?     │
│ - Physio      │ ├────┬─────┤ ├───────┬───────┤
│ - Orthotics   │ │MILD│SEVER│ │ YES   │ NO    │
│   (Lat Wedge) │ └─┬──┴──┬──┘ └──┬────┴───┬───┘
│ - Injection   │   ↓     ↓       ↓        ↓
└───────┬───────┘ Physio Surgery  Cast    Surgery
        ↓
     Failed?
        ↓
     Surgery

1. Conservative Management

  • Cast/Boot: 4-6 weeks for acute tears or acute subluxation (50% success for acute subluxation).
  • Physio: Proprioception, Peroneal strengthening.
  • Orthotics: Lateral forefoot wedge to offload peroneals? Or correct varus heel.

2. Surgical Management

A. For Tears

  1. Debridement/Tubularization:
    • If <50% of tendon cross-section involved.
    • Excise frayed edges. Suture remaining tendon into a tube.
  2. Tenodesis:
    • If >50% of tendon is degenerated.
    • Suture the rupture proximal stump to the intact tendon (e.g., Brevis to Longus).
    • "Side-to-side" anastomosis.
  3. Allograft:
    • For massive defects.

B. For Subluxation

  1. SPR Repair: Reattach retinaculum to fibula (anchors/drill holes).
  2. Groove Deepening:
    • If fibular groove is flat/convex.
    • Lift a bone flap, impoct cancellous bone, replace flap (preserves cartilage).
  3. Bone Block: Create a bony bumper (rarely done now).

C. Addressing Deformity

  • Calculaneal Osteotomy: If patient has rigid varus, you MUST perform a lateralizing calcaneal osteotomy or the repair will fail.

8. Complications

  • Sural Nerve Injury: Runs very close to surgical site. Numbness lateral foot.
  • Recurrent Subluxation: Failure of SPR repair.
  • Stiffness: Loss of inversion/eversion.
  • Peroneal Stenosis: Over-tightening the SPR causing compression.

9. Prognosis & Outcomes

  • Tears: Good results with tubularization (80-90% satisfaction).
  • Subluxation: Excellent results with groove deepening + SPR repair. Return to sport 3-4 months.

10. Evidence & Guidelines

Guidelines

  • AOFAS: Recommend surgical stabilization for chronic subluxation in athletes.

Landmark Trials

  • Saxena et al: Outcomes of Groove Deepening.
    • Result: 100% return to sport in athletic cohort. Groove deepening is safe and effective.
  • Demetracopoulos et al: MRI accuracy.
    • Result: MRI sensitivity for brevis tears is good (83%) but specificity is variable. Dynamic US is superior for instability.

11. Patient Explanation

What is the problem?

You have two tendons on the outside of your ankle that act like stirrups to stop you rolling over. One of them (Brevis) has split down the middle like a piece of string cheese, or the tunnel holding them (Retinaculum) has burst, letting them snap out of place.

The Surgery

We make a cut behind the ankle bone.

  1. If Torn: We sew the tendon back into a tube.
  2. If Snapping: We deepen the groove in the bone (like making a deeper gutter) and tighten the roof (retinaculum) back over it so they can't jump out.

Recovery

You will be in a boot for 6 weeks to let the repair heal. Sports usually at 3-4 months.

12. References

  1. Saxena A, et al. Surgical Treatment of Peroneal Tendon Subluxation in Athletes: A Retrospective Review. J Foot Ankle Surg. 2018.
  2. Demetracopoulos CA, et al. Peroneal Tendon Tears: A Retrospective Review. Foot Ankle Int. 2014.
  3. Philbin TM, et al. Peroneal tendon injuries. J Am Acad Orthop Surg. 2009.
  4. Ogden JA. The anatomy and function of the proximal tibiofibular joint. Clin Orthop Relat Res. 1974. (Describes Groove anatomy).
  5. Heckman DS, et al. Groove deepening for peroneal instability. Foot Ankle Int. 2008.
  6. Redfern D, Myerson M. The management of concomitant tears of the peroneus longus and brevis tendons. Foot Ankle Int. 2004.
  7. Digiovanni BF, et al. Associated injuries found in chronic lateral ankle instability. Foot Ankle Int. 2000.
  8. Krause JO, Brodsky JW. Peroneus brevis tendon tears: pathophysiology, surgical reconstruction, and clinical results. Foot Ankle Int. 1998.
  9. Dombek MF, et al. Peroneal tendon tears: a retrospective review. J Foot Ankle Surg. 2003.
  10. Sammarco GJ. Peroneal tendon subluxation. Am J Sports Med. 1994.

13. Examination Focus

Common Exam Questions (FRCS/Boards)

  1. Which tendon usually tears and why? (Answer: Brevis. It is deep and compressed against the fibula).
  2. What is the Fleck Sign? (Answer: Avulsion of SPR from fibula - diagnostic of dislocation).
  3. What is the gold standard investigation for subluxation? (Answer: Dynamic Ultrasound).
  4. How do you manage a >50% tear? (Answer: Tenodesis to the Longus).
  5. What deformity must be ruled out? (Answer: Cavovarus hindfoot. Needs specific testing/correction).

Viva "Buzzwords"

  • "Fleck Sign"
  • "Groove Deepening"
  • "Tubularization"
  • "Meat Grinder Effect"
  • "Dynamic Ultrasound"

Common Pitfalls

  • Missing a subluxation: Failing to do the provocation test.
  • Fixing top-down without checking base: Ignoring the varus heel will lead to failure of repair.
  • Sural Nerve damage: Careful dissection required.

At a Glance

EvidenceStandard
Last UpdatedRecently

Guidelines

  • NICE Guidelines
  • BTS Guidelines
  • RCUK Guidelines