Fibro-osseous Tunnel Research Articles

Multiparametric Ultrasound Assessment of Carpal Tunnel Syndrome: Beyond Nerve Cross-sectional Area.

Carpal tunnel syndrome (CTS), the most common mononeuropathy, results from compression of the median nerve within the fibro-osseous carpal tunnel. Diagnosis is typically based on clinical evaluation and confirmed by nerve conduction studies. However, ultrasound (US) has emerged as a valuable noninvasive adjunct for CTS confirmation, offering potential advantages over electrodiagnostic testing in terms of patient comfort and diagnostic accuracy. This review begins with a concise summary of carpal tunnel anatomy and CTS pathophysiology as a foundation for exploring the diverse applications of US in CTS evaluation. B-mode US assessment is presented with a focus on cross-sectional imaging and dynamic evaluations, including the transverse translocation and longitudinal gliding of the median nerve. We also review current methods for assessing vascularization in CTS and explore the usefulness of elastography in CTS evaluation. The advantages and limitations of each US method are elucidated, highlighting their practical utility in clinical practice.

Variations of the ulnar nerve within the ulnar tunnel and palm in a select South African population

BackgroundUlnar tunnel syndrome (UTS) is a rare peripheral neuropathy associated with the entrapment of the distal portion of the ulnar nerve (UN) in its course through the fibro-osseous ulnar tunnel (eponymously known as Guyon's canal) at the wrist. The UN within the ulnar tunnel is prone to injury or compression resulting in an UTS. Therefore, it is of clinical importance to know the anatomical variations in the branching pattern of the UN within the ulnar tunnel. UTS is characterised by sensory deficits and muscular weakness, impaired sensation of the volar fingertips, and weakness in grasping with intrinsic hand muscles. This study aimed to examine the anatomical variations of the UN in the palm of the hand within a select South African cadaveric population. MethodsThe variations in the branching patterns of the UN were examined in 81 cadavers (n = 162) and described according to the classification system of Murata et al. (2004) [10]. Communicating branches were classified according to their description in previous literature. The length of the ulnar tunnel was measured from the level of the pisiform bone to the level of the hook of hamate. ResultsThe branching pattern was found as Type 1 (52.9 %), Type 2 (34 %), Type 3 (2.7), Type 4 (6.5 %), Type 5 (3.9 %). Berrettini, Riche-Cannieu and Kaplan anastomoses were found in 51.6 %, 2 % and 3.3 % of specimens, respectively. ConclusionIt is important for surgeons to be aware of these anatomical variations as they may lead to misdiagnosis and complications during surgical procedures during the treatment of UTS.

Cubital tunnel syndrome: anatomy, pathology, and imaging.

Cubital tunnel syndrome (CuTS) is the second most common peripheral neuropathy in the upper limb. It occurs due to ulnar nerve compression within the fibro-osseous cubital tunnel at the elbow joint. Although CuTS is typically diagnosed clinically and with electrodiagnostic studies, the importance of imaging in evaluating the condition is growing. Knowing the typical imaging findings of ulnar nerve entrapment is necessary for precise diagnosis and proper treatment. In this article, we focus on the clinical features, workup and complex imaging of the "anatomic" cubital tunnel and relevant pathological entities.

Objective Evidence That Nerve Decompression Surgery Reduces Neuropathic DFU Recurrence Risk to Less than 5%

Significance: Despite 20 years of research and new treatment methods, diabetic foot ulcer (DFU) remains a common problem with frequent recurrences and complications. Recent Advances: There are reports that nerve decompression (ND) surgery has been observed to produce significantly fewer DFU recurrences than standard of care (SOC). The explanation of this apparent superiority has not been understood. Critical Issues: Microcirculation is understood to be involved in diabetic peripheral neuropathy (DPN) and DFU. There is an underappreciation of the participation in DPN of entrapment neuropathy (EN) due to nerve swelling and impingement in fibro-osseous tunnels. Reducing c-fiber compression in EN by ND generates recovery of subepidermal capillary flow. ND studies have found improved neuromuscular function and epidermal microcirculation phenomena, including chronic capillary ischemia (CCI) and pressure-induced vasodilatation (PIV). There is no current therapy recommended for impaired microcirculation. Clinical and animal evidence has demonstrated that release of locally compressed peripheral nerves improves the epidermal microcirculation which is under sympathetic control. Future Directions: Using epineurolysis to relieve nerve compressions is a physiology-based therapeutic intervention and provides the scientific foundation clarifying how ND reduces DFU recurrence risk. Incorporating ND with current SOC treatments could improve DFU recurrence risk, hard-to-heal ulcers, neuroischemic wounds, amputation risk, and the resulting costs to society. More studies using ND for DFU, especially evidence-based medicine Level I studies, are needed to confirm these preliminary outcomes.

Causes, symptoms, and treatments of nerve entrapments around the elbow: Current concepts

The elbow is a joint extremely susceptible to stiffness, even after a trivial trauma. As for other joints, several factors can generate stiffness such as immobilisation, joint incongruity, heterotopic ossification, adhesions, or pain. Prolonged joint immobilisation, pursued to assure bony and ligamentous healing, represents the most acknowledged risk factor for joint stiffness.The elbow is a common site of nerve entrapment syndromes. The reasons are multifactorial, but peculiar elbow anatomy and biomechanics play a role. Passing from the arm into the forearm, the ulnar, median, and radial nerves run at the elbow in close rapport with the joint, fibrous arches and through narrow fibro-osseous tunnel. The elbow joint, in fact, has a large range of flexion which exposes nerves lying posterior to the axis of rotation to traction and those anterior to compression.

Role of high-resolution ultrasound and magnetic resonance neurography in the evaluation of peripheral nerves in the upper extremity.

Upper extremity entrapment neuropathies are common conditions in which peripheral nerves are prone to injury at specific anatomical locations, particularly superficial regions or within fibro-osseous tunnels, resulting in pain and potential disability. Although neuropathy is primarily diagnosed clinically by physical examination and electrophysiology, imaging evaluation with ultrasound and magnetic resonance neurography are valuable complementary non-invasive and accurate tools for evaluation and can help define the site and cause of nerve dysfunction which ultimately leads to precise and timely treatment. Ultrasound, which has higher spatial resolution, can quickly and comfortably characterize the peripheral nerves in real time and can evaluate for denervation related muscle atrophy. Magnetic resonance imaging on the other hand provides excellent contrast resolution between the nerves and adjacent tissues, also between pathologic and normal segments of peripheral nerves. It can also assess the degree of muscle denervation and atrophy. As a prerequisite for nerve imaging, radiologists and sonographers should have a thorough knowledge of anatomy of the peripheral nerves and their superficial and deep branches, including variant anatomy, and the motor and sensory territories innervated by each nerve. The purpose of this illustrative article is to review the common neuropathy and nerve entrapment syndromes in the upper extremities focusing on ultrasound and magnetic resonance neurography imaging.

Review of De Quervain's tendinopathy

The tendons of the long thumb abductor (APL) and short thumb extensor (EPB), which travel through a fibroosseous tunnel in the styloid process of the radius, are afflicted by De Quervain's tendinopathy. This condition causes the tendons and the tunnel (or sheath) through which they pass to thicken non-inflammatorily. Individuals with this illness report radial side wrist discomfort that gets worse when the wrist and thumb are moved. The radial side of the wrist often has some swelling and discomfort. The physical examination findings, such as sensitivity and enlargement of the radial styloid in the first dorsal compartment and radial styloid pain with active or passive stretching of the thumb tendons over the radial styloids at thumb flexion, are used to make the diagnosis of de Quervain's tendinopathy (Finkelstein manoeuvre or test). The differential diagnosis includes calcified arthritis or tenosynovitis, intersection syndrome, ganglia, radial sensory nerve entrapment in the forearm, and osteoarthritis of the trapeziometacarpal joint (TMC). De Quervain's tendinopathy typically responds well to self-limiting therapies that alleviate symptoms. The patient's unique values and preferences have a significant role in the therapeutic decision. Nonsteroidal anti-inflammatory medicines (NSAIDs) for pain management, a forearm-based thumb splint, glucocorticoid injections, and surgery are all possible treatments. A forearm-based thumb splint with a free interphalangeal joint and a simultaneous NSAID pain reduction test are advised for individuals with de Quervain's tendinopathy. Patients with chronic pain and edema despite non-surgical therapy with splints and NSAIDs are advised to have glucocorticoid injections. Those who continue to experience symptoms despite nonsurgical treatment and glucocorticoid injection are typically the only ones who need surgery. De Quervain's tendinopathy is benign and self-limiting, therefore most patients are aware of this.

Hemiarthroplasty of the Ankle Joint: Mid-Term Results

Category: Ankle Arthritis; Ankle Introduction/Purpose: Tendinopathy of the flexor hallucis longus is a common condition that occurs with considerable frequency, but in some specific situations, due to a content (tendon)/continent (retomalleolar groove) conflict, could manifest a scenario in which the tendon suffers entrapment during its entry to the tunnel and clinically represented as hallux saltans Methods: We present a case report of a young active patient without any of the conditions or etiological agents previously described in the literature that could explain the cause of this rare condition. After failing conservative treatment, we performed arthroscopic release of the tendon and the fibrous tunnel, achieving direct visualization and minimal soft tissue injury Results: At 6 months, the patient resumed sports and activity of daily living without any type of sequelae. Conclusion: Hallux saltans is a rare condition mostly idiopathic in its origin. After conservative measures fail, surgical management is an option, which consists of resecting FHL enlargement to its original width and freeing the fibro-osseous tunnel in the back of the talus in order to solve the space conflict during its normal gliding. An arthroscopic approach is optimal as it allows a good visualization without harming soft tissues and allowing a quicker recovery.

Idiopathic hallux saltans an unusual presentation of flexor hallucis longus tendinopathy: a case report

Hallux saltans is a rare condition characterized by an entrapment of the flexor hallucis longus. Its tendon passes through the retromalleolar groove below the flexor retinaculum, directing the plantar aspect of the foot through a fibro-osseous tunnel below the sustentaculum tali. This study presents a young active patient without any of the conditions or etiological agents previously described in the literature that could explain the cause of this rare condition. After failing conservative treatments, an arthroscopic release of the tendon and the fibrous tunnel was performed, achieving direct visualization and minimal soft tissue injury. At six month follow-up, the patient resumed sports and daily living activities without symptoms. Level of Evidence V; Therapeutic Studies; Expert Opinion.

Design and In Vivo Testing of Novel Single-Stage Tendon Graft Using Polyurethane Nanocomposite Polymer for Tendon Reconstruction

Severe trauma, failure of prior surgical repair, delayed presentation and excessive scarring around the flexor tendon bed often necessitate a two-stage surgical reconstruction, where a silicone spacer is used in the first stage to recreate the fibro-osseous tunnel through which the tendon graft can glide in the second stage. This staged procedure involves great commitment on the part of both patient and surgeon, over the course of several months, involving a prolonged period of rehabilitation that can be quite disruptive to the patient's life and work. Reducing this from a two-stage into a single-stage procedure, therefore, has the potential to reduce rehabilitation time and cost, expedite return to work, and improve outcomes. To address this, we developed polyurethane (PU) nanocomposite, as an engineered tendon sheath, for treatment of delayed flexor tendon division as a single-stage procedure. The clinically conformant tubular grafts were tested for their efficacy in the peroneus tertius tendon of 6 Mule sheep for 3 months. Semi-quantitative histological assessment was carried out by analysing four descriptive layers: tendon, tendon/polymer sheath interface, polymer sheath, and polymer sheath/surrounding tissue. Four (out of 6) of the implanted PU nanocomposites showed moderate to substantial healing of the injured tendons, with minimal adhesion after repair, ensuring good gliding movement. No statistical differences were observed in tendon repair based on intra-regional variation in the explanted grafts, indicating homogeneity in tendon repair. Overall, the PU nanocomposite bears morphological stability and functionality for tendon repair, in single-stage surgical reconstruction, demonstrating promising evidence for clinical translation.

Anatomical Study of Stabilizing Structures of the Extensor Carpi Ulnaris Tendon Around the Wrist

The sixth dorsal extensor compartment is a relatively common site of stenosing tenosynovitis in the upper extremity, but the exact location of stenosis is not fully understood. The objective of this study was to investigate the detailed anatomy of structures surrounding the extensor carpi ulnaris (ECU) tendon around the wrist. Fifty fresh human cadaveric wrists were used for gross observation and morphology measurements of the sixth dorsal compartment and the ECU subsheath. An additional 13 wrists were used for histological examination. We evaluated the morphology of supporting structures in 3 regions: the ulnar groove (zone I), the ulnar styloid process (zone II), and the triquetrum (zone III). The fibro-osseous tunnel comprising the ulnar groove and the overlying subsheath (zone I) stabilized the ECU tendon, and the subsheath had thin membranous collagen fibers attached to the periosteum. We consistently found the distal extension of ECU subsheath (zone II), which connected the ulnar styloid process and the dorsal radioulnar ligament. Variations in the length of the distal extension increased with the forearm in pronation. Collagen fiber thickness around the ECU tendon in zone II was greater than that of zone I. In zone III, the overlying extensor retinaculum and septa, which were composed of thick circumferential collagen structures, supported the ECU tendon by attaching to the triquetrum on both sides of the ECU tendon. We found the presence of an ulnar septum of the sixth compartment attached to the triquetrum in 84% of dissected wrists. The ECU tendon was supported by the ECU subsheath, which had thin and elastic collagen fibers over the ulnar groove. Distal extension of the subsheath and surrounding radial and ulnar extensor retinaculum septa attached to the triquetrum provided thicker supporting structures. Stenosing ECU tenosynovitis may occur not only in the ulnar groove but also in the more distal ulnar styloid process and triquetrum areas.

Surgical efficacy analysis of tarsal tunnel syndrome: a retrospective study of 107 patients.

Tarsal tunnel syndrome (TTS) is an entrapment neuropathy of the posterior tibial nerve or its terminal branches compressed by its fibro-osseous tunnel beneath the flexor retinaculum on the medial side of the ankle. The current study was a retrospective study of 107 cases of patients with TTS, in which the onset characteristics were summarized, the factors that might affect the surgical treatment effects of TTS were discussed and analyzed. The syndrome diagnoses and treatment experiences of TTS were extracted and analyzed. In our cohort, TTS was more often found in middle-aged and older women. And the medial plantar nerve bundle was the most frequently affected nerve structure. The efficacy of surgical treatment were correlated to the causes of the disease, involved nerve bundles, methods of operation, and whether neurolysis of the epineurium was performed. Neurolysis of the epineurium is was recommended for patients with an enlarged tibial nerve due to impingement. The Singh method was recommended to release the tibial nerve and its branches. Patients with negative preoperative EMG results should carefully be cautious when considering their decision to undergo surgical treatment.

Comparative Study of Flexor Hallicus Longus Tendon Length through Single Incision or Accessory Plantar Medial Incision: A Cadaver Study

Category:Ankle; HindfootIntroduction/Purpose:Flexor Hallucis Longus (FHL) tendon transfer to the calcaneus is a common adjuvant procedure in the treatment of Achilles pathology. The FHL tendon can be harvested using a posterior incision where the tendon is dissected along its course into the fibroosseous tunnel. Alternatively, the FHL may be harvested through a separate plantar medial incision as it crosses the flexor digitorium longus at the Knot of Henry. This study aims to quantify FHL tendon lengths achieved through the two common approaches utilizing pair matched cadavers.Methods:Seven pair matched fresh-frozen cadaver legs without signs of musculoskeletal abnormalities were used for this assessment. One leg in each pairing underwent a single incision harvest while the contralateral leg underwent an accessory medial plantar harvest. After dissecting the tendon, a calcaneus tunnel was prepared from dorsal to plantar in both calcanei in standard fashion. Two measurements were obtained. The first measurement was taken from the distal aspect of the muscle belly to the distal end of the tendon. The tendon was then pulled through the calcaneus, and the foot was held in tension at 20 degrees of plantar flexion. The second measurement was taken from site where tendon entered the calcaneous to the distal end of the tendon graft. The measurements were analyzed using Wilcoxon Signed Ranks Test and Fischer Exact Test.Results:Using a posterior incision, the mean tendon measurement from calcaneous tunnel to the distal end of the tendon was 4.0 cm. Using an accessory plantar medial incision, the mean tendon measurement from the calcaneous tunnel to the distal end of the tendon was 7.2 cm. The average tunnel length obtained using an accessory medial incision was significantly greater than the length obtained using the single incision approach (p= 0.0003, p=0.0022, and p=0.0016). The accessory plantar medial incision obtained an FHL tendon tunnel length that was an average of 2.9 cm greater than the posterior incision.Conclusion:The single incision approach provided sufficient length to safely anchor the FHL into the calcaneus which suggests that the accessory plantar medial approach is not necessary for routine FHL transfers to the calcaneus with interference screw fixation. However, if additional length is needed for other applications such as posterior tibialis tendon dysfunction or peritoneal tendon tears, the accessory incision does provide an average of 2.9 cm of additional length.

Anatomical variation in the first extensor compartment during treatment of De Quervain'S tenosynovitis

Background: De Quervain's disease is ste¬nosing tenosynovitis of the abductor pollicis longus and the extensor pollicis brevis within the first extensor retinaculum compartment of the wrist. The patient usually present with clinical symptoms like pain and a painful range of motions of the thumb which occur either due to increased friction force or due to increase in contain within the compartment during the gliding of the adductor pollicis longus (APL) and the extensor pollicis brevis (EPB) first extensor compartment. Following conservative trials of rest, moist heat, NSAID, and local steroid injections, surgical release of the first compartment are effective treatment modalities for De Quervain's disease, but these even leads to failure of treatment as there may be variation on the anatomy of first extensor compartment of wrist. We had done this study to find out anatomical variation in first extensor compartment during treatment of De Quervains tenosynovitis. Method: Anatomical Variations like presence or absence of septum between APL and EPB, number of tendon slip of APL and EPB in the first extensor compartment were studied in 16 patients of dequervains tenosynovitis who underwent open surgical release as the treatment. Result: 7/16 (43.75%) of patient has partial or complete Sub compartment in the fibro-osseous tunnel and 4/16 (25%) patient has extra Abductor Pollicis Longus (APL) tendon sheath in first extensor compartment. Conclusion: We found significant increase in variation of anatomy in first extensor compartment of De Quervains tenosynovitis patient which will be for the surgeon during the surgical release of first extensor compartment.

The Lister’s tubercle trapdoor: a minimally invasive technique for harvesting cancellous bone from the distal radius

Bone graft harvest from the distal radius, immediately proximal to the Lister's tubercle, is a common technique in upper limb surgery. Here, we present a minimally invasive technique to harvest bone graft using a replaceable, well vascularized access trapdoor. The hinged trapdoor technique allows a small incision over Lister's tubercle and does not violate the fibro-osseous tunnel of the third compartment. Nearby structures like the superficial radial nerve, extensor carpi radialis brevis and extensor pollicis longus are safely protected throughout. Closure of the trapdoor creates a smooth surface and therefore little or no surrounding trauma.

Clinical and Ultrasonographic Features of Distal Ulnar Neuropathy: A Review.

Focal ulnar neuropathy at the wrist is a rare but problematic disorder often associated with the unique anatomy of this nerve as it courses through Guyon's canal, a superficial fibro-osseous tunnel in the proximal ulnar palm. The electrophysiologic features of this disorder have been well-characterized, but the sonographic anatomy of the nerve across the wrist and palm has yet to be systematically described in normal and abnormal states. In this review, we describe the basic anatomy and the sonographic appearance of the nerve in the wrist and palm in normals and individuals with pathology. The value of using US in conjunction with electrodiagnostic testing is emphasized as the two tests together provide critical information regarding etiology, predisposing factors, and functional significance. Furthermore, ultrasound is useful as a patient educational tool to promote behavioral changes that assist in nerve recovery when pathology is related to repetitive stress.

Wide-Awake Flexor Tendon Repair Under Tumescent Injection

Background. Flexor tendon injuries are frequent, due to variable hand activities, and the repair is challenging to hand surgeons, especially in zone II, because of the coexistence of two tendons within a tight fibro-osseous tunnel. Flexor tendon repair under tumescent infiltration provides anesthesia and a bloodless field, so that no tourniquet or sedation is needed. Aim of study. The goal of this study was to identify a surgical adjustment and intraoperative total active movement examination of the repaired tendon so that no gapping is formed, and smooth gliding is obtained, avoiding tendon rupture and producing an optimal range of motion. Patients and method. From January 2016 to April 2017, 9 patients (17 tendons), with a mean age of 31.8 years, presented within 3 to 14 days of injury to zone I or zone II of their flexor tendons. Tendon repair was done under tumescent infiltration (lidocaine 1% with adrenaline 1:200,000) only, with no tourniquet or sedation, and with an intraoperative total active movement examination. Result. After 6 months of follow up, all the patients had excellent range of motion according to the Boyes outcome scale, and none showed signs of postoperative tendon rupture. Conclusion. Tumescent infiltration for flexor tendon repair allows intraoperative surgical adjustment and total active movement examination, which will minimize postoperative rupture and adhesion. This procedure will also facilitate the surgeon’s work by eliminating the need for general anesthesia or sedation; however, this procedure is not applicable for children, major trauma, or those who are mentally challenged.

Biologic and mechanical aspects of tendon fibrosis after injury and repair

ABSTRACTTendon injuries of the hand that require surgical repair often heal with excess scarring and adhesions to adjacent tissues. This can compromise the natural gliding mechanics of the flexor tendons in particular, which operate within a fibro-osseous tunnel system similar to a set of pulleys. Even combining the finest suture repair techniques with optimal hand therapy protocols cannot ensure predictable restoration of hand function in these cases. To date, the majority of research regarding tendon injuries has revolved around the mechanical aspects of the surgical repair (i.e. suture techniques) and postoperative rehabilitation. The central principles of treatment gleaned from this literature include using a combination of core and epitendinous sutures during repair and initiating motion early on in hand therapy to improve tensile strength and limit adhesion formation. However, it is likely that the best clinical solution will utilize optimal biological modulation of the healing response in addition to these core strategies and, recently, the research in this area has expanded considerably. While there are no proven additive biological agents that can be used in clinical practice currently, in this review, we analyze the recent literature surrounding cytokine modulation, gene and cell-based therapies, and tissue engineering, which may ultimately lead to improved clinical outcomes following tendon injury in the future.

Arthroscopic decompression of the flexor hallucis longus tendon in posttraumatic tendinopathy

Background: Tenosynovitis of the flexor hallucis longus (FHL) tendon is more frequent than previously reported, and the condition is often overlooked or misdiagnosed. Overuse in ballet dancers or competitive runners was believed to be the main triggering factor. Recent advances in diagnostic modalities have shown a wide occurrence in nonathletes. The purpose of this study was to evaluate arthroscopic decompression of the FHL tendon in posttraumatic tenosynovitis. Methods: Nine consecutive patients with posttraumatic flexor hallucis longus stenosing tenosynovitis were treated and enrolled in this prospective study. All patients dated their complaint to previous ankle fracture or major sprain. The standard procedure included posterior ankle arthroscopy, thorough debridement of posterior adhesions, and adequate decompression of the tendon at the fibroosseous tunnel. Patients were evaluated for functional outcome through both Foot and Ankle Outcome Score (FAOS) and Ankle-Hindfoot Scale. Results: The mean FAOS score at 1-year follow-up improved from a preoperative mean of 72.56 (SD 4.43) to a postoperative mean of 87.33 (SD 4.03), which is considered to be extremely statistically significant with a P value less than 0.0001. The mean Ankle-Hindfoot Scale improved from a preoperative mean of 71.78 (SD 3.77) to a postoperative mean of 85.33 (SD 5.94). All patients reported being fully satisfied with an overall satisfaction score of 9.42. Conclusions: Flexor hallucis longus stenosing tenosynovitis is more frequent than previously thought and should be considered in patients with posterior ankle pain especially if a history of ankle trauma exists.

Arthroscopic Treatment of Flexor Hallucis Longus Tenosynovitis

Category: Arthroscopy Introduction/Purpose: Flexor Hallucis Longus (FHL) tenosynovitis is a common cause of posterior ankle pain, typically associated with repetitive plantar flexion activities. The purpose of this study was to report the results of patients with FHL tenosynovitis treated with posterior ankle arthroscopy using validated outcome measures and develop a zone-based classification of FHL tenosynovitis that demonstrates well correlated preoperative imaging and intraoperative findings. Methods: Posterior ankle arthroscopy was performed in 11 patients (12 ankles) with a diagnosis of FHL tenosynovitis, with patients followed for a minimum of two years (mean 44 months). Outcomes were evaluated using validated scoring measures, including visual analog scales (VAS) for pain, 12-Item Short Form Health Survey (SF-12), and the Foot and Ankle Ability Measure (FAAM). Results: A zonal classification scheme based on anatomic location was developed, divided into three zones: proximal to the ankle joint, posterior to the ankle joint, and from the fibro-osseous tunnel underneath the sustentaculum tali to the FHL insertion. Agreement between preoperative MRI and arthroscopic zonal involvement at time of surgery was present in ten feet (83%), and differed in two feet (17%). VAS scores improved significantly from 7.1 ± 1.4 preoperatively to 1.3 ± 1.3 postoperatively (p <0.001). Mean values for ADL and sports subscales of the FAAM at time of follow up were 87.1 ± 16.2 and 76.5 ± 28.8, respectively. Physical component summary (PCS) and mental component summary (MCS) of the SF-12 yielded means of 51.3 ±12.8 and 52.7 ± 5.0, respectively. Conclusion: FHL pathology can be classified using a zone-based classification scheme, which is highly correlative between preoperative MRI and intraoperative findings. Posterior ankle arthroscopy is an effective treatment option for FHL tenosynovitis, as evaluated using validated outcome measures.