Posterior Ankle Impingement

This is an extremely complex case of FAILED posterior ankle impingement surgery that tests advanced understanding of causes of surgical failure, revision surgical planning, and comprehensive differential diagnosis. There are several CRITICAL teaching points. First, understanding the POTENTIAL CAUSES of persistent symptoms after os trigonum excision: (1) INCOMPLETE OSSEOUS EXCISION - residual os trigonum fragment left behind: This is the MOST COMMON cause of failed os trigonum surgery. The os trigonum may be LARGER than appreciated arthroscopically, or may have extensions that are not fully visualized. If any fragment of the os trigonum remains (even small 5mm fragments), it can continue to cause impingement during plantarflexion. This patient's post-op X-ray shows a 5mm RESIDUAL FRAGMENT and MRI shows bone marrow edema in this fragment - this is SYMPTOMATIC incomplete excision. The operative report describes 'os trigonum identified and excised arthroscopically' but clearly the entire ossicle was NOT removed. This is a technical failure. (2) UNRECOGNIZED OR INADEQUATELY TREATED FHL PATHOLOGY: The operative report states 'FHL visualized and appeared normal. No release performed as no evidence of stenosis.' However, this patient NOW has clear evidence of FHL stenosis and tenosynovitis (thickened tendon 8mm, high T2 signal, fluid around sheath, clinical triggering/snapping). This raises the question: Was FHL pathology PRESENT pre-operatively but MISSED (inadequate pre-op assessment or inadequate intraoperative assessment)? OR Did FHL pathology DEVELOP POST-OPERATIVELY (secondary to surgical scarring or compensatory overload after os trigonum excision)? Looking at the history: She did NOT have FHL triggering/clicking PRE-operatively (this is NEW post-op symptom). This suggests the FHL pathology may have developed AFTER surgery, possibly due to: Post-surgical SCARRING in the posterior ankle causing FHL tethering/stenosis, or Altered biomechanics after os trigonum excision causing increased FHL stress. However, it is also possible that mild FHL tenosynovitis was present pre-operatively (it commonly accompanies os trigonum syndrome) but was not recognized or addressed during surgery. (3) POST-SURGICAL SCARRING/FIBROSIS: Endoscopic surgery in the posterior ankle can cause scarring in the posterior recess. This scar tissue can cause continued impingement symptoms even if the os trigonum is completely removed. The MRI mentions 'post-surgical scarring in posterior ankle recess' which could be contributing. (4) ALTERNATIVE/ADDITIONAL PATHOLOGY MISSED: Could there be other causes of posterior impingement that were not identified initially? Examples: Prominent STIEDA PROCESS (elongated lateral talar tubercle - continuous with talus, not separate like os trigonum). If the surgeon only excised the os trigonum but there is ALSO a prominent Stieda process, symptoms would persist. Posterior capsular pathology, Other soft tissue impingement. However, in this case the imaging suggests residual os trigonum and FHL pathology are the likely culprits. (5) NERVE INJURY OR NEUROMA: Endoscopic posterior ankle surgery carries risk of nerve injury (sural nerve laterally, tibial nerve/medial plantar nerve medially). If a nerve was injured or a neuroma developed, this could cause persistent pain. However, her pain pattern (reproduced with impingement test, associated with mechanical symptoms) is more consistent with mechanical impingement than neuropathic pain. For ANALYZING THIS SPECIFIC CASE: The MRI findings are CRITICAL - they show TWO distinct pathologies: (1) Residual 5mm os trigonum fragment with bone marrow edema - this is INCOMPLETE EXCISION causing persistent osseous impingement, (2) FHL tendinopathy and stenosing tenosynovitis (8mm thickened tendon, stenosis in tunnel, fluid around sheath) - this is causing her NEW triggering/clicking symptoms and contributing to posterior pain. BOTH need to be addressed for successful outcome. Her persistent posterior impingement test positivity suggests the residual os trigonum fragment is still impinging. Her NEW FHL triggering/snapping indicates FHL pathology that was either missed initially or developed post-operatively. For COUNSELING THE PATIENT about what went wrong: This requires BALANCED and HONEST discussion: (1) INCOMPLETE EXCISION: The post-op X-ray shows a residual fragment of the os trigonum was left behind. This is a technical issue with the initial surgery. Os trigonum can be larger and have more extensions than appreciated during arthroscopy, and complete excision can be challenging. However, leaving a 5mm symptomatic fragment is suboptimal and is contributing to her ongoing symptoms. (2) FHL PATHOLOGY: Your FHL tendon is now showing significant pathology (thickening, inflammation, stenosis) which is causing the new clicking/snapping you're experiencing. This may have been present but missed at the initial surgery, OR it may have developed afterward due to scarring or altered mechanics. Either way, it needs to be addressed. (3) NOT a surgical complication per se (no infection, no nerve injury) but the surgery was INCOMPLETE and did not achieve the desired outcome. This happens in a small percentage of cases (reported failure rates for os trigonum excision are 5-15%). (4) Importantly, this is FIXABLE with revision surgery if done comprehensively. For REVISION SURGERY PLANNING - what would be different: If revision surgery is undertaken, it MUST address BOTH the residual os trigonum fragment AND the FHL pathology. A revision procedure would include: (1) COMPLETE EXCISION of residual os trigonum fragment: Re-establish the endoscopic portals (may be some scarring from previous surgery), Identify the residual 5mm fragment (use fluoroscopy intraoperatively to confirm location), Excise the ENTIRE residual fragment - ensure NO osseous material remains. This may require burring down the lateral talar tubercle to ensure complete excision, Confirm complete excision with fluoroscopy intraoperatively (no residual fragment visible on fluoroscopic lateral view). (2) COMPREHENSIVE FHL RELEASE AND TENOSYNOVECTOMY: RELEASE the fibro-osseous tunnel where the FHL is stenosed (between medial and lateral talar tubercles), Perform TENOSYNOVECTOMY - remove ALL inflamed synovium around the FHL tendon sheath, If the FHL tendon has significant tendinopathy (which MRI suggests - 8mm thickened, high T2 signal), may need to perform longitudinal SPLIT of the tendon to decompress, BUT must preserve tendon substance/strength (do NOT excise tendon - only split longitudinally). This is critical for a professional dancer, Intraoperatively TEST FHL gliding - passively move the great toe through full flexion/extension while visualizing the FHL arthroscopically. It should glide FREELY without restriction. If there is still restriction, further release is needed. (3) DEBRIDEMENT of post-surgical SCAR TISSUE: Excise any fibrous scar tissue in the posterior ankle recess that may be contributing to impingement, Ensure adequate decompression of the posterior recess. (4) Consider OPEN vs ENDOSCOPIC approach for revision: ENDOSCOPIC revision is possible but may be technically more challenging due to scarring from previous surgery. Visualization may be compromised. OPEN approach (posteromedial incision) may give better access to both the residual os trigonum and the FHL, particularly if extensive FHL work is needed. The decision depends on surgeon comfort and extent of pathology. For a PROFESSIONAL DANCER with significant FHL pathology, I would lean toward OPEN approach to ensure comprehensive FHL release and avoid under-treating the FHL (which was the problem in the first surgery). (5) Post-operative protocol would be similar to primary surgery: 2 weeks NWB in boot, progressive WB 2-4 weeks, early ROM exercises to prevent re-scarring (CRITICAL - more aggressive ROM than after primary surgery to break up adhesions), return to dance training 12-16 weeks, return to professional performance 4-6 months. For RISKS OF REVISION SURGERY - must counsel appropriately: (1) SCAR TISSUE is more extensive in revision surgery - anatomic planes are obscured, risk of nerve injury is HIGHER in revision than primary surgery (sural nerve, tibial nerve, medial plantar branch), (2) Risk of PERSISTENT symptoms despite revision - if there is extensive scarring or if FHL is severely damaged, symptoms may not fully resolve. Revision surgery outcomes are LOWER than primary surgery (primary os trigonum excision 85-95% good outcomes, revision surgery 70-80% good outcomes), (3) Risk of FHL WEAKNESS if too much tendon is debrided - this would be DEVASTATING for a professional dancer. Must preserve tendon substance, (4) Risk of STIFFNESS from post-op scarring - early aggressive ROM is critical, (5) Standard surgical risks (infection, wound complications, etc.). For ALTERNATIVE DIAGNOSES to consider (what else could be causing her pain): While the MRI findings strongly suggest residual os trigonum and FHL pathology are the causes, we should consider: (1) Could this be NEUROPATHIC pain from nerve injury rather than mechanical impingement? Features AGAINST neuropathic pain: Pain reproduced by posterior impingement test (mechanical), Pain related to plantarflexion (mechanical), No burning/shooting/dysesthetic quality described, No hypersensitivity to light touch (allodynia). Features FOR neuropathic pain would be: Burning, shooting, electric pain, Hypersensitivity, Pain out of proportion to exam findings. In this case, mechanical impingement is more likely. (2) Could this be COMPLEX REGIONAL PAIN SYNDROME (CRPS)? Features AGAINST CRPS: No color changes, temperature differences, or swelling, Pain pattern is mechanical (related to plantarflexion), No allodynia. CRPS typically has more dramatic clinical findings. (3) Could there be ANTERIOR ankle impingement (osteophytes) causing pain that is being misinterpreted as posterior? Unlikely - pain is clearly posterior on exam, anterior impingement causes pain with DORSIflexion not plantarflexion. (4) Could this be ACHILLES TENDINOPATHY? Unlikely - Achilles is non-tender on exam, pain is DEEP posterior (not superficial insertion), impingement test positive. In this case, I am confident the diagnosis is residual os trigonum + FHL pathology based on imaging and clinical findings. RECOMMENDATION AND SHARED DECISION-MAKING: This is a complex situation requiring detailed discussion with the patient about her goals and risk tolerance. OPTIONS: (1) REVISION SURGERY (my recommendation): Comprehensive revision procedure addressing BOTH residual os trigonum fragment AND FHL pathology (complete excision of fragment, FHL release and tenosynovectomy, scar debridement). Consider OPEN approach for better visualization and comprehensive FHL work. Realistic expectations: 70-80% chance of good outcome (lower than primary surgery), 4-6 months to return to professional performance, risk that symptoms may not completely resolve despite revision. (2) CONSERVATIVE MANAGEMENT: Trial of: Intensive physiotherapy focusing on FHL strengthening and stretching, Corticosteroid injection to posterior ankle and FHL sheath, Activity modification. However, given she has STRUCTURAL problems (residual bone fragment, FHL stenosis), conservative management is unlikely to provide lasting relief. This may temporize symptoms but won't fix the underlying issues. (3) ACCEPT LIMITATIONS and modify career: Some dancers with persistent posterior ankle issues modify their technique or transition to less demanding roles. This is a LAST RESORT if surgery fails or patient declines revision. For a 26-year-old professional dancer, I would RECOMMEND revision surgery with realistic counseling about outcomes and risks. The alternative is accepting career-limiting symptoms which at her age and level seems premature. However, she needs to understand this is higher-risk revision surgery, not a simple repeat of the first operation. SUMMARY: This is failed os trigonum surgery due to: (1) INCOMPLETE EXCISION (5mm residual fragment - technical failure), (2) UNRECOGNIZED/UNTREATED FHL pathology (either missed initially or developed post-op). Revision surgery must address BOTH pathologies comprehensively. Consider open approach for better access. Revision outcomes are lower than primary (70-80% vs 85-95%) and patient must be counseled about risks including nerve injury, persistent symptoms, FHL weakness. Alternative diagnoses (neuropathy, CRPS) are unlikely based on clinical and imaging findings.