Anterior and posterior ankle arthroscopy for impingement, osteochondral lesions and loose bodies · intermediate
- Anterolateral portal risks the superficial peroneal nerve (intermediate dorsal cutaneous branch) — transilluminate or mark the nerve with the ankle plantarflexed and inverted before incision; the nerve lies approximately 1 cm proximal to the joint line in 80 percent of ankles.
- Anteromedial portal is made just medial to the tibialis anterior tendon — the saphenous vein and nerve lie immediately medial and must be protected by blunt dissection and staying close to the tendon.
- Posterior arthroscopy (prone) uses posterolateral and posteromedial portals on either side of the Achilles — the posterolateral portal protects the sural nerve by staying immediately lateral to the Achilles, and the posteromedial portal stays immediately medial to the Achilles but strictly lateral to the flexor hallucis longus tendon to avoid the posterior tibial neurovascular bundle.
- Non-invasive distraction with a well-padded strap or external fixator distractor is standard; invasive distraction with a calcaneal pin increases the risk of pin-site infection, nerve injury and fracture and is rarely required.
When & Why
Indications — anterior ankle arthroscopy - Anterior bony or soft-tissue impingement refractory to at least 3 months of conservative treatment
- Osteochondral lesions of the talus (OLT) accessible from anterior portals (typically anterolateral or central talar dome)
- Loose bodies within the anterior or central ankle joint
- Synovitis or arthrofibrosis limiting motion after trauma or previous surgery
- Assisted reduction and fixation of certain intra-articular fractures (Tillaux, Chaput fragments)
- Diagnostic arthroscopy when MRI is equivocal and symptoms persist Indications — posterior ankle arthroscopy - Posterior impingement (os trigonum, Stieda process, posterior talar process fracture non-union)
- Flexor hallucis longus tenosynovitis or stenosis
- Posterior loose bodies or osteochondral lesions not accessible anteriorly
- Posterior ankle arthrofibrosis or capsular contracture
- Assisted posterior ankle fusion in selected cases Absolute contraindications are active septic arthritis or an open wound at the portal sites, severe ankle arthritis with less than 50 percent joint space remaining (consider arthrodesis), and vascular insufficiency precluding tourniquet use or wound healing. Relative contraindications are previous extensive open surgery with distorted anatomy, complex regional pain syndrome (which may worsen with arthroscopy), and a patient unable to comply with post-operative rehabilitation.
- Anterior arthroscopy
- Supine with non-invasive distraction
- Posterior arthroscopy
- Prone with non-invasive distraction
- Anterior arthroscopy
- Anteromedial and anterolateral
- Posterior arthroscopy
- Posteromedial and posterolateral
- Anterior arthroscopy
- Superficial peroneal nerve (anterolateral portal)
- Posterior arthroscopy
- Sural nerve (posterolateral); posterior tibial neurovascular bundle (posteromedial)
- Anterior arthroscopy
- Anterior impingement, anterior OLT, loose bodies
- Posterior arthroscopy
- Posterior impingement, os trigonum, FHL pathology
- Anterior arthroscopy
- 2–5 percent temporary superficial peroneal neuropraxia
- Posterior arthroscopy
- 1–3 percent sural or tibial nerve injury
- Anterior arthroscopy
- 6–12 weeks for impingement resection
- Posterior arthroscopy
- 8–16 weeks for os trigonum excision
Consent. Counsel specifically on nerve injury (2–5 percent temporary, less than 1 percent permanent), incomplete resolution of impingement, iatrogenic chondral injury, infection (less than 1 percent), and the possibility of conversion to open surgery. Setup. Supine for anterior work with a non-invasive distraction strap on the foot attached to a distractor or sandbag; for combined anterior and posterior work, anterior arthroscopy is completed first and the patient is then repositioned prone, or a single posterior procedure is performed prone from the outset. General or spinal anaesthesia with a thigh tourniquet at 250–300 mmHg; a regional ankle block may be added for post-operative analgesia, and prophylactic antibiotics are given at induction. Equipment: a 2.7 mm or 4.0 mm 30-degree arthroscope (4.0 mm preferred for posterior work), a non-invasive distraction device or padded strap, a radiofrequency ablation device, a 3.5 mm or 4.5 mm shaver, microfracture awls, curved curettes and a 70-degree scope for posterior visualisation.
The Operation
The goal is to enter the ankle joint through safe portals, protect the cutaneous nerves and the posterior tibial neurovascular bundle at every step, and treat the target pathology — anterior impingement, an osteochondral lesion, loose bodies or posterior impingement — with minimal chondral damage. The whole operation is built around portal placement: the exposure is the operation, and the two portal systems (anterior then posterior) are laid out step by step below.
Operative sequence
- With the ankle distracted, mark the joint line by palpation.
- The portal sits lateral to the peroneus tertius or extensor digitorum longus tendon, just lateral to the talar dome.
- Transilluminate the proposed portal site with the ankle in plantarflexion and inversion before any incision — the superficial peroneal nerve (intermediate dorsal cutaneous branch) crosses 8–15 mm proximal to the joint line in most ankles and is the structure most often injured.
- Make a vertical 5 mm skin incision only, then spread bluntly with a haemostat down to the capsule and insert a blunt trocar and cannula. Never plunge a knife into the capsule.
- Insert the 30-degree scope through the anterolateral portal and inspect the anterior joint.
- Identify the tibialis anterior tendon at the joint line. The anteromedial portal is made immediately medial to it.
- Localise with an 18-gauge needle first to confirm intra-articular position, then spread bluntly and insert the cannula.
- The saphenous vein and nerve lie 3–5 mm medial to the portal — staying immediately adjacent to the tendon and using blunt dissection protects them.
- Inspect systematically: medial gutter, medial talar dome, central talar dome, lateral talar dome, lateral gutter, anterior tibial plafond and anterior capsule.
- Document chondral lesions, loose bodies, synovitis and impingement lesions with a probe.
- Note that the anterior capsule attaches 5–8 mm proximal to the tibial plafond and 8–12 mm distal to the talar dome articular margin; the posterior 20–30 percent of the talar dome is not seen from anterior portals and needs a 70-degree scope or a posterior approach.
- Use a 3.5 mm shaver or radiofrequency probe to resect anterior osteophytes and hypertrophic synovium from the tibial plafond and talar neck.
- Preserve at least 50 percent of the talar dome articular surface to avoid iatrogenic instability or accelerated arthritis.
- Remove loose bodies with a grasper.
- For a contained lesion less than 15 mm, debride unstable cartilage flaps back to a stable rim with a curette.
- Perform microfracture with 2 mm awls spaced 3–4 mm apart to a depth of 3–4 mm until fat droplets appear.
- For larger or uncontained lesions, consider osteochondral autograft transfer (OATS) or autologous chondrocyte implantation after discussion.
- For a posterior procedure, position the patient prone with non-invasive distraction.
- Mark the Achilles tendon and the posterior joint line (approximately 1.5–2 cm proximal to the tip of the lateral malleolus).
- Create the posterolateral portal immediately lateral to the Achilles tendon. The sural nerve and small saphenous vein lie 1–2 cm lateral to the portal, so staying against the tendon is protective.
- Insert the scope (4.0 mm preferred) and identify the FHL tendon medially.
- With the scope in the posterolateral portal, identify the FHL tendon.
- Create the posteromedial portal immediately medial to the Achilles tendon under direct vision, staying strictly lateral to the FHL.
- Insert a cannula. All instrumentation now stays strictly lateral to the FHL tendon.
- All work occurs in the safe interval lateral to the FHL tendon, between the FHL and the peroneal tendons.
- Resect the os trigonum or posterior talar process with a shaver or burr, working from lateral to medial while keeping the FHL in view.
- Debride FHL tenosynovitis, remove posterior loose bodies, and inspect the posterior talar dome and tibial plafond.
- Confirm complete resection by dynamic examination — dorsiflexion and plantarflexion under direct vision.
- Close portals with 3-0 nylon or absorbable suture.
- Apply a sterile dressing; add a posterior splint if microfracture was performed, otherwise a compression bandage suffices.
- Anterolateral portal — superficial peroneal nerve. The most commonly injured structure in ankle arthroscopy. Transilluminate in plantarflexion and inversion; blunt dissection only after the skin incision.
- Anteromedial portal — saphenous vein and nerve. They lie immediately medial to the tibialis anterior tendon. Stay against the tendon and avoid deep medial retraction.
- Posterolateral portal — sural nerve. Stay immediately lateral to the Achilles (within 5 mm of the tendon edge); the sural nerve lies 1–2 cm lateral to the portal.
- Posteromedial working space — posterior tibial neurovascular bundle. Lies medial to the FHL within the tarsal tunnel. The FHL tendon is the absolute medial boundary: never cross medial to it with any instrument.
- Talar dome cartilage and distraction. Aggressive instrumentation or loss of distraction scores the thin articular surface. Maintain distraction of 6–8 mm and release it periodically in long cases; distraction greater than 8–10 mm risks ligament injury or fracture.
Always transilluminate the anterolateral portal site with the ankle plantarflexed and inverted. The superficial peroneal nerve is visible as a blue line in most patients. Make a vertical skin incision only, then spread with a haemostat — never plunge a knife into the capsule. Failure to transilluminate misses the nerve in up to 20 percent of ankles.
In the posterior compartment the FHL tendon is the medial fence. Keep every instrument and the shaver strictly lateral to the FHL. If you lose visualisation of the FHL, stop, re-identify it, and only then continue. Crossing medial to the FHL risks direct injury to the posterior tibial neurovascular bundle.
Aftercare & Complications
Rehabilitation | Phase | Timing | Immobilisation | Therapy focus | |-------|--------|-----------------|---------------| | Immediate (day 0–14) | 0–2 weeks | Portals dry 48 hours; compression bandage, or posterior splint if microfracture | Touch weight-bearing 48 hours then full; active range of motion from day 1 | | Microfracture | 0–6 weeks | Non-weight-bearing in a removable boot or cast | Continuous passive motion 6 hours daily; active range of motion from week 2 | | Strengthening | 6–12 weeks | Boot weaned from week 6 | Theraband and isometrics, gait normalisation, proprioception | | Return to sport | 3–9 months | None | Sport-specific drills and plyometrics; running 4–6 months after microfracture | Keep portals dry for 48 hours, then begin daily cleaning with chlorhexidine; remove sutures at 10–14 days. After impingement resection alone the patient is full weight-bearing within 48 hours with immediate active range of motion. After microfracture, 6 weeks non-weight-bearing with continuous passive motion, progressive weight-bearing from week 6, return to running at 4–6 months and to sport at 6–9 months. Typical returns to function: sedentary work 1–2 weeks, manual labour 4–6 weeks, impact sport 3–4 months for impingement resection. Physiotherapy milestones — week 2: full active range of motion, scar massage, proprioception; week 6: strengthening and gait normalisation; week 12: sport-specific drills and plyometrics if the microfracture has healed; ongoing: maintenance proprioception and peroneal strengthening to prevent re-injury. Complications
- Incidence
- 2–5 percent temporary; less than 1 percent permanent
- Recognition
- Numbness or painful neuroma on the dorsum of the foot; positive Tinel at the portal
- Prevention and management
- Prevent by transillumination in plantarflexion-inversion and blunt dissection. Manage neuropraxia by observation; explore and repair, or excise a symptomatic neuroma, after 3 months
- Incidence
- 1–3 percent
- Recognition
- Lateral foot numbness or painful neuroma; positive Tinel behind the lateral malleolus
- Prevention and management
- Prevent by keeping the posterolateral portal immediately adjacent to the Achilles. Observe; explore a painful neuroma if it develops
- Incidence
- less than 0.5 percent (rare but catastrophic)
- Recognition
- Immediate plantar numbness, absent pulses, or ischaemic changes
- Prevention and management
- Prevent by working strictly lateral to the FHL. Immediate vascular exploration and repair; urgent fasciotomy if compartment syndrome develops
- Incidence
- 1–3 percent (often under-reported)
- Recognition
- Cartilage scoring or flap on post-operative MRI or second-look arthroscopy
- Prevention and management
- Maintain distraction, use blunt instruments near cartilage, avoid an aggressive shaver near the dome. Microfracture a new full-thickness lesion
- Incidence
- less than 1 percent
- Recognition
- Erythema, discharge, or persistent sinus at the portal 2–4 weeks post-operatively
- Prevention and management
- Meticulous sterile technique, single-use cannulae, early suture removal. Oral antibiotics for cellulitis; debridement and sinus excision if chronic
- Incidence
- 5–10 percent for impingement
- Recognition
- Persistent pain and mechanical symptoms at 3–6 months; MRI or CT shows residual bone or soft tissue
- Prevention and management
- Systematic inspection of all gutters and the posterior compartment; confirm resection intra-operatively. Repeat arthroscopy with more aggressive resection if refractory
- Incidence
- less than 1 percent
- Recognition
- Disproportionate pain, swelling, colour and temperature changes, allodynia beyond 6 weeks
- Prevention and management
- Gentle tissue handling, early mobilisation, adequate analgesia. Early pain-team referral; multimodal therapy with gabapentinoids, sympathetic blocks and graded motor imagery
Viva & Exam Focus
PORTALSPORTALS — anterior and posterior landmarks
ANKLEANKLE — when arthroscopy changes management
Critical danger structures — nerves and vessels around the portals
Location: the intermediate dorsal cutaneous branch crosses the anterolateral ankle approximately 1 cm proximal to the joint line in 80 percent of cases; it is subcutaneous and vulnerable during portal creation. Risk: transection causes a painful neuroma or numbness on the dorsum of the foot. Temporary neuropraxia reaches 2–5 percent in large series; permanent injury is less than 1 percent with careful technique. Fix: transilluminate the portal site in plantarflexion and inversion; make a vertical skin incision only, then blunt dissection with a haemostat down to the capsule.
Location: the saphenous vein and its accompanying nerve lie immediately medial and slightly anterior to the tibialis anterior tendon at the joint line. Risk: vein laceration causes troublesome bleeding that obscures the view; nerve injury causes medial foot numbness or a painful neuroma. Fix: stay at the lateral border of the tibialis anterior tendon; blunt spreading after the skin incision; avoid deep medial retraction.
Location: runs immediately lateral to the Achilles tendon in the posterior ankle, approximately 1–2 cm lateral to the posterolateral portal site. Risk: injury during posterolateral portal placement causes lateral foot numbness or a painful neuroma; reported in up to 3 percent without careful technique. Fix: create the portal immediately lateral to the Achilles under direct vision or transillumination; stay within 5 mm of the tendon edge.
Location: the posterior tibial artery, vein and tibial nerve lie medial to the FHL within the tarsal tunnel, approximately 1 cm medial to the FHL at the level of the posterior ankle joint. Risk: direct injury or thermal damage from a shaver or radiofrequency causes catastrophic ischaemia or complete plantar numbness. Fix: identify the FHL first from the posterolateral portal; all posteromedial work stays strictly lateral to the FHL — never cross medial to it.
Location: the key landmark separating the safe working space (lateral to the FHL) from the neurovascular bundle (medial to the FHL). Risk: injury to the FHL causes great-toe flexion weakness and may allow the neurovascular bundle to drift laterally into the working field. Fix: keep the shaver and instruments lateral to the FHL at all times; use the FHL as the medial boundary of the posterior compartment.
Location: the thin articular cartilage on the talar dome and tibial plafond is easily scored; excessive distraction stresses the ligaments. Risk: full-thickness chondral injury accelerates arthritis; distraction greater than 8–10 mm risks ligament injury or fracture. Fix: maintain constant joint-surface visualisation; use non-invasive padded distraction of 6–8 mm, released periodically in long cases.
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 28-year-old footballer presents with anterior ankle pain and limited dorsiflexion after repeated ankle sprains. MRI shows a small anterior osteophyte on the tibial plafond and an anterolateral OLT measuring 12 mm. How do you plan his arthroscopic procedure?”
“You are planning posterior ankle arthroscopy for a 22-year-old dancer with posterior impingement from an os trigonum. Describe your portal placement, key anatomical landmarks, and how you avoid the posterior tibial neurovascular bundle.”
“A 35-year-old patient is 4 months after anterior ankle arthroscopy and microfracture for a 14 mm OLT. She has persistent pain and swelling. MRI shows incomplete fill of the lesion with subchondral oedema. What are the possible reasons for failure and your revision options?”
Key indications
- Anterior impingement (bony or soft-tissue) refractory to 3 months of conservative treatment
- Posterior impingement (os trigonum, Stieda process) in athletes and dancers
- Osteochondral lesions of the talus less than 15 mm and contained — microfracture first-line
- Loose bodies, synovitis, arthrofibrosis
- Assisted fracture work or fusion in selected cases
Anterior portals and nerve safety
- Anterolateral portal: lateral to the peroneus tertius; transilluminate in plantarflexion-inversion to protect the superficial peroneal nerve
- Anteromedial portal: immediately medial to the tibialis anterior tendon; protects the saphenous vein and nerve
- Superficial peroneal nerve crosses 8–15 mm proximal to the joint line in 80 percent of ankles — the most commonly injured structure
- Blunt dissection after the skin incision is mandatory for both anterior portals
Posterior portals and the FHL landmark
- Posterolateral portal: immediately lateral to the Achilles; protects the sural nerve
- Posteromedial portal: immediately medial to the Achilles but strictly lateral to the FHL tendon
- The FHL tendon is the absolute medial boundary — the posterior tibial neurovascular bundle lies medial to it
- Never cross medial to the FHL with any instrument or shaver
Distraction and equipment
- Non-invasive distraction with a padded strap or external fixator distractor is standard and safe
- Invasive calcaneal-pin distraction is reserved for rare inadequate-access cases; it adds pin-site infection and nerve risk
- 2.7 mm or 4.0 mm 30-degree scope (4.0 mm preferred posteriorly); a 70-degree scope helps the posterior compartment
- Maintain 6–8 mm of distraction; release it periodically in long cases
Complications and prevention
- Superficial peroneal nerve injury: 2–5 percent temporary — prevented by transillumination and blunt dissection
- Sural nerve injury: 1–3 percent — prevented by a portal immediately adjacent to the Achilles
- Posterior tibial neurovascular injury: less than 0.5 percent but catastrophic — never cross medial to the FHL
- Iatrogenic chondral injury: 1–3 percent — maintain distraction and visualisation
- Portal infection or sinus: less than 1 percent — meticulous sterile technique and early motion
Rehabilitation milestones
- Immediate active range of motion from day 1 unless microfracture was performed
- Microfracture: 6 weeks non-weight-bearing with continuous passive motion
- Impingement resection alone: full weight-bearing within 48 hours
- Return to running 3–6 months; return to sport 6–9 months after microfracture
- Physiotherapy focus: proprioception, peroneal strengthening, scar massage
Background & Evidence
Osteochondral lesions of the talus — lesion characteristics drive treatment. Arthroscopic management of an OLT depends on size, containment and whether the articular shoulder is intact. A lesion that is contained and less than 15 mm is managed with debridement and microfracture as first-line; a lesion that is uncontained, involves the shoulder, or is greater than 15 mm has a higher failure rate with microfracture alone and is considered for osteochondral autograft transfer (OATS) from the ipsilateral knee, allograft, or autologous chondrocyte implantation. Very large lesions or kissing tibial-talar lesions may ultimately need arthrodesis or arthroplasty after biological options fail.
- First-line management
- Debride to a stable rim and microfracture
- Outcome and note
- Approximately 80 percent good fill at 2–5 years; the evidence-based default
- First-line management
- OATS (autograft from the ipsilateral knee) or allograft
- Outcome and note
- Microfracture alone has a higher failure rate; revision to OATS is common
- First-line management
- Consider arthrodesis or arthroplasty
- Outcome and note
- Arthroscopy rarely changes the outcome
Outcome evidence. Arthroscopic resection of anterior impingement gives 85–90 percent good results in athletes, with return to sport typically at 8–12 weeks after structured rehabilitation. Posterior arthroscopy for os trigonum excision yields greater than 90 percent good results in van Dijk's series. Microfracture for a contained OLT is successful in approximately 80 percent at 2–5 years. Non-invasive distraction is sufficient in about 96 percent of cases (Amendola). The overall complication rate of ankle arthroscopy is around 9 percent (Ferkel), and nerve injury accounts for roughly half of all complications — which is why portal placement and transillumination dominate the technique.
References
Complications in foot and ankle arthroscopy
A large series of foot and ankle arthroscopies analysing complication patterns; the overall complication rate is around 9 percent and nerve injury predominates — the basis for transillumination and blunt dissection to minimise the most common complication.
A 2-portal endoscopic approach for diagnosis and treatment of posterior ankle pathology
The two-portal posterior endoscopic technique is safe and effective for posterior ankle pathology, using the FHL tendon as the key medial landmark — the foundation of modern posterior ankle arthroscopy.
Arthroscopic treatment for anterior ankle impingement — a systematic review of the current literature
A systematic review supporting arthroscopic resection for anterior ankle impingement, with good outcomes and quicker recovery, making it preferred over open resection in athletes.
Microfracture for osteochondral lesions of the talus — a systematic review of reporting of outcome data
A systematic review of microfracture for OLT, highlighting variable outcome reporting and the importance of lesion size and containment in patient selection.