First Metatarsal Headphones-Like Lesion: A Case of Unreducible Sesamoid Complex Dislocation.

CASE: A 34-year-old woman sustained a direct trauma to the left hallux during a fall. Radiographs showed a dorsal dislocation of the first metatarsophalangeal joint and a wide separation of sesamoid complex. Closed reduction was tried: postreduction radiographs displayed reduction of first metatarsophalangeal joint and a complete sesamoid complex dislocation. The patient was scheduled for surgery. Through a medial approach, open reduction together with plantar structures release and repair were performed. Functional and radiographic outcomes were satisfactory at the last follow-up. CONCLUSION: In case of a "headphones-like lesion" surgery is required, together with plantar structures repair.

Medial sesamoid position in moderate to severe hallux valgus: Correlation between three radiographic measurements.

BACKGROUND: In hallux valgus surgery, it is essential to accurately assess the position of the sesamoids both pre- and postoperatively. Weight-bearing foot anteroposterior, tangential sesamoid, and semi-weight-bearing computed tomography axial views are radiographic methods used to assess the medial sesamoid position. This study aimed to measure the medial sesamoid position and evaluate the correlation between these three radiographic methods. METHODS: This retrospective study comprised 59 feet from 49 patients who underwent hallux valgus surgery. The mean age of patients was 54.6 (range, 22-70) years. We took preoperative and postoperative measurements using the weight-bearing anteroposterior, tangential sesamoid, and semi-weight-bearing computed tomography axial views to assess the medial sesamoid position. RESULTS: The mean grades of the medial sesamoid position preoperatively and 6 months postoperatively were 2.5 and 0.8, 1.6 and 0.4, and 1.3 and 0.3 points based on the anteroposterior, tangential sesamoid, and computed tomography axial views, respectively (P < 0.001). Preoperatively, there was a strong positive correlation between the computed tomography axial and tangential sesamoid views (P < 0.001, r = 0.645) and anteroposterior and computed tomography axial views (P < 0.001, r = 0.468). In contrast, the tangential sesamoid and anteroposterior views showed a weak positive correlation (P = 0.03, r = 0.283). Six months postoperatively, there was a positive correlation between the computed tomography axial and tangential sesamoid views (P < 0.001, r = 0.473), anteroposterior and computed tomography axial views (P < 0.001, r = 0.470), and tangential sesamoid and anteroposterior views (P < 0.001, r = 0.480). CONCLUSIONS: We observed that the anteroposterior view exhibited a higher degree of medial sesamoid position displacement than the computed tomography axial and tangential sesamoid views. For the preoperative evaluation of the medial sesamoid position, the correlation between the computed tomography axial and tangential sesamoid views was stronger than that between the tangential sesamoid and anteroposterior views. However, all three views showed strong correlations postoperatively.

Fracture of the fabella with radiologic and MRI.

The fabella is an inconstant sesamoid bone. A handful of cases have been reported so far describing fabella fracture, usually involving high energy mechanism or stress fractures after total knee arthroplasty. This paper presents a fabella fracture in a man in his 40s after suffering a car crash, the clinical and radiographic presentation, treatment and complete recovery at 4-months follow-up.

Correlations of Sesamoid Bone Subluxation with the Radiologic Measures of Hallux Valgus and Its Clinical Implications.

Background and Objectives: Hallux valgus is one of the most common chronic foot complaints, with prevalences of over 23% in adults and up to 35.7% in older adults. However, the prevalence is only 3.5% in adolescents. The pathological causes and pathophysiology of hallux valgus are well-known in various studies and reports. A change in the position of the sesamoid bone under the metatarsal bone of the first toe is known to be the cause of the initial pathophysiology. Purpose: The relationships between the changes in the location of the sesamoid bone and each radiologically measured angle and joint congruency in the hallux valgus remain as yet unknown. Therefore, this study investigated the relationships of sesamoid bone subluxation with the hallux valgus angle, intermetatarsal angle, and metatarsophalangeal joint congruency in hallux valgus patients. The goal is to know the hallux valgus angle, the intermetatarsal angle, and metatarsophalangeal joint congruency's correlation with hallux valgus severity and prognosis by revealing the relationship between each measured value and sesamoid bone subluxation. Materials and Methods: We reviewed 205 hallux valgus patients who underwent radiographic evaluation and subsequent hallux valgus correction surgery in our orthopedic clinic between March 2015 and February 2020. Sesamoid subluxation was assessed using a new five-grade scale on foot radiographs, and other radiologic measurements were assessed, such as hallux valgus angle, the intermetatarsal angle, distal metatarsal articular angle, joint congruency, etc. Conclusions: Measurements of the hallux valgus angle, interphalangeal angle, and joint congruency exhibited high interobserver and intraobserver reliabilities in this study. They also showed correlations with sesamoid subluxation grade.

A modified minimally invasive osteotomy for hallux valgus enables reduction of malpositioned sesamoid bones.

BACKGROUND: The current minimally invasive distal metatarsal osteotomy for hallux valgus (HV) is V-shaped, which prevents the correction of the rotational metatarsal head deformity and reduction of the sesamoid bones. We sought to determine the optimal method for sesamoid bone reduction during HV surgery. METHODS: We reviewed the medical records of 53 patients who underwent HV surgery between 2017 and 2019 using one of three techniques: open chevron osteotomy (n = 19), minimally invasive V-shaped osteotomy (n = 18), and a modified straight minimally invasive osteotomy (n = 16). The sesamoid position was graded using the Hardy and Clapham method on weight-bearing radiographs. RESULTS: When compared to open chevron and V-shaped osteotomies, the modified osteotomy resulted in significantly lower postoperative sesamoid position scores (3.74 ± 1.48, 4.61 ± 1.09, and 1.44 ± 0.81, respectively, P < 0.001). Furthermore, the mean change in postoperative sesamoid position score was greater (P < 0.001). CONCLUSION: The modified minimally invasive osteotomy was superior to the other two techniques in correcting HV deformity in all planes, including sesamoid reduction.

Locking of the Metacarpophalangeal Joint of the Thumb Caused by Entrapment of the Radial Sesamoid Bone.

Locking of metacarpophalangeal (MCP) joints of the thumb may be a consequence of dorsal subluxation from hyperextension injury. The joint is locked in mild hyperextension and cannot flex actively or passively. We report four patients with locked MCP joint of the thumb due to radial sesamoid entrapment after hyperextension or forced flexion injury. All patients had a prominent radial condyle of the metacarpal bone. Three patients had a deformity of the longitudinal groove on which the sesamoid was overlaid. The radial sesamoid was entrapped proximal to the radial condyle which could result in limited extension and hinged flexion of the joint. Excision of the radial sesamoid could release the locked joint. The radial sesamoid should be assessed if the motion of the thumb MCP joint is limited after flexion or extension injury. Level of Evidence: Level V (Therapeutic).

Sesamoidectomy in Athletes: Outcomes From 2-Centers.

Sesamoid pain can arise from avascular necrosis, fracture, osteochondrosis, and advanced degeneration. Disorders of the sesamoids in athletes can be debilitating. Total sesamoidectomy of the involved sesamoid is considered an effective surgical treatment when conservative measures have failed. There is limited literature evaluating the outcome of sesamoidectomy in athletically active patients. Our 2-center study reports on 68 patients (70 procedures; 2 male patients were operated on both feet in separate procedures approximately 3 years apart; 41 (58.6%) tibial and 29 (41.4%) fibular sesamoidectomies; 24 males and 44 females, average age 28.4 ± 12.2 years) who underwent total sesamoidectomy from 01/2001 to 12/2019. In our cohort, the average time to return to activity (RTA) was 11.1 ± 5.1 weeks, with no statistically significant difference between gender and age, or between fibular and tibial sesamoidectomy in relation to RTA. There was a minimum follow-up of 1 year, with an average of 106.6 ± 66.6 months. The total incidence of complication rate was 5.7%. In athletes in whom conservative management has failed, sesamoidectomy is safe, and allows predictable return to their chosen sport. To our knowledge, none of the patients subsequently developed pathology to the remaining sesamoid.

Arthroscopic Sesamoidectomy for Hallux Sesamoid Disorders.

In this retrospective case series, we aimed to study arthroscopic sesamoidectomy, including surgical methods, clinical outcomes, and complications. We retrospectively reviewed the medical records of patients with hallux sesamoid disorders who underwent arthroscopic sesamoidectomy from July 2015 to July 2017. The visual analog scale for rating pain, Japanese Society for Surgery of the Foot scale scores, number of days taken to return to normal daily living, number of months taken to return to playing sports, and complications were analyzed. The mean follow-up duration was 3.2 years. Among 14 patients, there were 8 females and 6 males (median age: 39 years). The mean visual analog scale score improved from 75.4 to 14.3 mm; the mean Japanese Society for Surgery of the Foot score improved from 55.2 to 88.0 points. The mean time to return to activities of daily living was 5.3 days. Among the 5 patients who played sports, 3 and 2 patients resumed playing sports at 3 and 12 postoperative months, respectively. Complications included wound pain (n = 4), discomfort in severe weather (n = 4), numbness (n = 3), pain in the sole other than in the ball of the foot (n = 2), pain during hallux dorsiflexion (n = 2), residual sesamoid discomfort (n = 1), swelling (n = 1), toe-in gait (n = 1), and metatarsal head bone marrow edema (n = 1). Despite good clinical outcomes of arthroscopic sesamoidectomy, patients should be made aware of the many potential complications of this procedure prior to surgery.

Concentrated Bone Marrow Aspirate Injection for Hallux Sesamoid Disorders.

Concentrated bone marrow aspirate (CBMA) offers an alternative to sesamoid resection in end stage sesamoid pathology. CBMA potentiates the anti-inflammatory effect, stimulates local tissue regeneration and osteogenesis, when injected into bone. The purpose of this study is to evaluate the functional outcomes in a cohort of athletes following CBMA injection for the treatment of hallux sesamoid disorders. A retrospective case series of consecutive patients treated with CBMA injection for hallux sesamoid disorders were identified. Radiographs, Foot and Ankle Outcome Scores (FAOS), and Visual Analogue Scale (VAS) score were collected pre- and postinjections. Descriptive statistics were presented as the mean and standard deviation for continuous variables and frequency as percentages for categorical variables. Fifteen consecutive patients with were included with a mean follow-up time of 20.1 (range 12-34) months. Significant improvement in all scoring subscales of the FAOS and VAS score was noted preinjection compared to final follow-up postinjection (p < .001). Eight of 11 patients that were involved in sports prior to the CBMA injection returned to play, with 7 successfully returning to preinjury level status. Three patients required further treatment (20%). The case series suggests that CBMA injection is a safe and effective treatment option for hallux sesamoid disorders with a high rate of return to play.

Treatment of Fabella syndrome with arthroscopic fabellectomy: a case series and literature review.

BACKGROUND: The fabella is a sesamoid bone in the posterolateral capsule of the human knee joint. In quadrupedal mammals, the fabella is believed to have a role similar to the patella in redirecting extension forces of the knee joint from one point to another. In bipeds, the fabella is not touching the back of the bent knee, and therefore the role in redirecting forces declines. Posterolateral knee pain can be associated with the irritation between the fabella and lateral femoral condyle, a phenomenon also known as fabella syndrome. In cases that are unresponsive to conservative management, surgical fabellectomy can be a successful treatment option. Among the surgical approaches, open resection is most commonly seen. There are also literature reporting arthroscopic-assisted open resection, but seldom mentioned the all-arthroscopic fabellectomy. CASE PRESENTATION: We present 3 patients with a long history (> 12 month) of posterolateral knee pain under suspicion of different pain origins. The diagnosis of fabella impingement was eventually made by ruling out of other causes. All the patients underwent all-arthroscopic fabellectomy for diagnosis and treatment. Investigations of the resected fabella suggested chronic impingement with apparent osteophyte formation and cartilage wearing of the articular side. All patients have been continually followed up at our outpatient department and reported to be pain free after the procedure. CONCLUSIONS: In the patients presenting posterolateral pain, fabella syndrome cannot be ignored due to its relative higher presence in Asian population. In our experience, the all-arthroscopic fabellectomy offers a smaller wound size, less post-operative pain, fewer days of hospitalization and quicker time to rehabilitation for the patients with chronic posterolateral knee pain caused by fabella syndrome.

Common Peroneal Nerve Palsy Due to Giant Fabella After Total Knee Arthroplasty.

BACKGROUND: Common peroneal nerve palsy (CPNP) is a rare but serious complication following primary total knee arthroplasty (TKA). The common peroneal nerve is one of the main molecules of the sciatic nerve. CPNP is a series of symptoms caused by common peroneal nerve injury due to paralysis and atrophy of the fibula and tibia muscles. The main clinical symptoms are: ankle joint unable to extend back, toe unable to extend back, foot droop, walking in a steppage gait, and foot dorsal skin sensation having decreased or disappeared. If treatment is not timely, severe cases may result in atrophy of the anterior tibia and lateral calf muscles. The risk factors for CPNP include mechanical stretching of the nerve, disruption of the blood supply to the nerve, and compression of the nerve. The CPNP should be treated in a timely manner and according to the cause. Its function should be restored as soon as possible to avoid serious adverse consequences. It has negative effects on patients' life and physical and mental health. To our knowledge, this is the first study to describe CPNP due to a giant fabella after TKA. CASE PRESENTATION: The present study reported on a 70-year-old female patient. The patient underwent a primary TKA of the right knee for osteoarthritis. Relevant examinations were conducted and the operation went smoothly. Three hours postoperation, a right partial CPNP was observed, with progressive aggravation over time. On palpation, there was a 2 × 2-cm fixed hard mass in the posterolateral aspect of the right knee, with mild tenderness to deep palpation. Radiographs demonstrated that a giant fabella was located at the posterolateral condyle of the right femur. Fabellectomy and neurolysis of the common peroneal nerve were performed. The peroneal nerve palsy resolved gradually after the operation. At 8-month follow up after fabellectomy and neurolysis, the function of the common peroneal nerve had fully recovered. CONCLUSIONS: The presence of giant feballa pressing on the common peroneal nerve should be considered when common peroneal nerve palsy occurs after TKA. Surgical exploration and release compression should be performed in a timely manner.

Classification of Hallucal Sesamoid Bone Correlated with Hallux Valgus Severity.

The hallucal sesamoid bones (HSBs), having an important role in reducing load per unit area on the first metatarsal head, can be injured commonly which also affected the first metatarsophalangeal joint and the surrounding structure. Meanwhile, differences among each HSB type may be a major factor affecting the occurrence and development of HV. So far, many researchers had learned that there are three different conditions in hallucal sesamoid bone affecting the choice of clinical surgery corresponding to different solutions in clinic. Thus, it is necessary to study the anatomical morphological characteristics of the HSB which can be helpful in clinical diagnosis and treatment, especially hallux valgus (HV). 150 X-ray and three-dimensional (3D) computed tomographic (CT) images consist of 72 left and 78 right metatarsals were applied in this anatomic study between two variables and showed by a simple scatter plot. The first metatarsophalangeal joint is divided into four different types: type I (no HSB, 1.3%), type II (with one HSB, 0.07%), type IIIa (with two HSBs when THB is bigger, 28%), type IIIb (with two HSBs when FHB is bigger, 65.3%), and type IV (with three HSBs, 4.7%). There was no statistical difference between the left and right sides, except HVA, Meary, and pitch (P < 0.05); all a, b, c, d, and i have statistical difference between male and female (P < 0.05). Meanwhile, HVA and IMA and HVA and type group have a significant correlation. In summary, HVA and IMA and HVA and classification of HSBs have significant correlations. The classification and location of HSBs can be an important basis to choose operation methods and postoperation evaluation.

Arthroscopic Synovectomy and Excision of a Sesamoid in the Management of an Atypical Presentation of Avascular Necrosis of Bone: A Case Report.

Avascular necrosis of a sesamoid bone is a rare and incompletely understood entity. Furthermore, associated lesions secondary to sesamoid pathology have seldom been described in the literature. We report a case of avascular necrosis of the medial sesamoid, accompanied by severe synovitis of the first metatarsophalangeal joint, that was successfully managed with arthroscopic synovectomy and open excision of the sesamoid.

Intrinsic Fixation of the Tibial Sesamoid in First Metatarsophalangeal Joint Arthrodesis: A Cadaveric Study.

Nonunion rate of first metatarsophalangeal joint (MTP) joint arthrodesis is reportedly less than 6%, regardless of fixation type. Robust modern plating constructs aim to decrease incidence of nonunion while also allowing early postoperative weight-bearing. Quicker transition to weight-bearing postoperatively increases patient adherence, decreases adjacent joint stiffness, and reduces risk of deep vein thrombosis in the postoperative period. The purpose of this study was to investigate the effect tibial sesamoid fixation has on first MTP joint arthrodesis.

Functional and patient reported outcomes following lateral hallucal sesamoidectomy.

BACKGROUND: Lateral hallucal sesamoidectomy is an infrequently performed procedure indicated for patients with sesamoid pathology failing conservative treatment. Concerns exists regarding patient satisfaction, plantar scar pain, hallux malalignment and metatarsophalangeal joint (MTPJ) movement restriction following sesamoidectomy. This study aims to assess patient satisfaction after lateral hallucal sesamoidectomy via the plantar approach. METHODS: In this retropective study with prospective follow-up, all patients who underwent lateral hallucal sesamoidectomy between January 2004 and December 2017 were reviewed. Twelve patients (14ft.) were available for final assessment. Outcome measures were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) clinical rating scale and the Self-Reported Foot and Ankle questionnaire (SEFAS). Patients were assessed clinically and radiologically. The average postoperative follow-up was 111.5 months (range 28-177 months). RESULTS: All patients reported excellent outcome scores with a mean SEFAS score of 46.08 (range 43-48) and a mean AOFAS score of 92.33 (range 78-100) at final follow-up. All twelve patients reported their outcome as being excellent. No malalignment was noted clinically, however, three patients had a noticeable increase in the gap between the hallux and second toe when compared to the contralateral side. Range of motion at the MTPJ was preserved with a mean dorsiflexion of 80.83° (range 70-90°) and a mean plantarflexion was 25.83° (range 0-30°). None of the patients experienced any pain, discomfort or irritation related to the plantar scar. One patient developed neuroma like symptoms in the first web space. CONCLUSION: Lateral hallucal sesamoidectomy via a plantar approach is an effective and reliable treatment option as demonstrated by the high levels of patient satisfaction, preservation of function, excellent PROM scores and limited complications in this study. LEVEL OF EVIDENCE: Level 4.

Relationships Between First Metatarsal and Sesamoid Positions and Other Clinically Relevant Parameters for Hallux Valgus Surgery.

Relationships between hallux valgus (HV) and other measurements within the first ray have been extensively studied. It is becoming more popular to correct HV deformity with tarsometatarsal joint arthrodesis while internally (varus) rotating the first metatarsal. This, in turn, reduces the sesamoid position when viewed in the dorsoplantar projection on radiographs. However, it has been shown that not all HV deformities have pathological external (valgus) rotation of the first metatarsal. In this study, we explored the relationships between frontal-plane rotations of the first metatarsal as well as the sesamoids, and other factors not limited to the first ray, to better understand the pathological process of HV deformity and to assist in surgical planning. We found that when adjusting for these covariates, the only factor associated with first metatarsal external rotation was having less metatarsus adductus. Sesamoid rotation, on the other hand, was independently associated with the HV angle, tibial sesamoid position, and medial column collapse. When surgically treating HV, correction of sesamoid rotation may need to be prioritized.

Osteochondral fragments of the pastern joint at the origin of the collateral ligament of the distal sesamoid bone: performance after arthroscopic removal (2000-2015).

OBJECTIVE: To describe the presence of fragments in the dorsal proximal interphalangeal (PIP) joint and to report flat racing performance after surgical treatment. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Thirty-nine affected thoroughbred flat racehorses and 169 age- and sex-matched maternal siblings. METHODS: Medical records from 2000 to 2015 were reviewed for thoroughbred horses that underwent arthroscopic removal of osteochondral fragments in the dorsal aspect of the PIP joint. The horses' 2-year-old year, 3-year-old year, and career athletic performances were compared with their matched siblings. RESULTS: Thirty-nine thoroughbred horses were included, varying in age from 4 months to 4 years, with osteochondral fragments in 42 PIP joints. Hind limbs (92%) were more commonly affected than forelimbs (8%). Fragments were located within the origin of the collateral ligament of the distal sesamoid (navicular) bone. After surgery, the likelihood of starting a race did not differ between treated horses (27/39 [69%]) and maternal siblings (129/169 [76%], P = .15). Race earnings did not differ between treated horses and their siblings during their 2-year-old year (P = .66), 3-year-old year (P = .43), or career (P = .60). CONCLUSION: Removing osteochondral fragments from the origin of the collateral ligament of the distal sesamoid bone did not impair the ability to race or earning potential for affected thoroughbred racehorses compared with their maternal siblings. CLINICAL SIGNIFICANCE: Fragments from the dorsal aspect of the PIP joint in racehorses can be removed arthroscopically resulting in a good clinical outcome and future flat racing performance comparable to matched controls.

Efficacy, Outcomes, and Alignment Following Isolated Fibular Sesamoidectomy via a Plantar Approach.

BACKGROUND: The purpose of this study was to evaluate patients for intermediate-term pain relief, functional outcome, and changes in hallux alignment following isolated, complete fibular sesamoidectomy via a plantar approach for sesamoid-related pain recalcitrant to conservative treatment. METHODS: A retrospective query of a tertiary referral center administrative database was performed using the Current Procedural Terminology code 28135 for sesamoidectomy between 2005 and 2016. Patients who underwent an isolated fibular sesamoidectomy were identified and contacted to return for an office visit. The primary outcome measure was change in visual analog pain score at final follow-up. Secondary measures included satisfaction, hallux flexion strength, hallux alignment, pedobarographic assessment, and postoperative functional outcome scores. Patients who met the 2-year clinical or radiographic follow-up minimum were included. Ninety fibular sesamoidectomies were identified. Thirty-six sesamoidectomies met inclusion criteria (median 60-month follow-up). The average patient was 36 years old and underwent sesamoidectomy 1.1 years after initial diagnosis. RESULTS: Median visual analog scale scores improved 5 (6 to 1) points at final follow-up (P < .001). Final postoperative mean hallux valgus angle did not differ from preoperative values (10.5 degrees/8.5 degrees, P = .12); similarly, the intermetatarsal angle did not differ (8.0 degrees/7.9 degrees, P = .53). Eighty-eight percent of patients would have surgery again and 70% were "very satisfied" with their result. Hallux flexion strength (mean 14.7 pounds) did not differ relative to the contralateral foot (mean 16.1 pounds) (P = .23). Among the full 92 case cohort, 3 patients underwent 4 known reoperations. CONCLUSION: Fibular sesamoidectomy effectively provided pain relief (median 5-year follow-up) for patients with sesamoid pathology without affecting hallux alignment. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Hallux sesamoid fractures in young athletes.

Objective: To describe the evaluation, management and recovery time of hallux sesamoid fractures in young athletes.Methods: A retrospective chart review was performed in a large academic teaching institution over a 5-year period (1/1/2010-12/31/2014). All patients with a sesamoid injury were initially included. Excluded were those patients who: 1) did not receive the diagnosis of hallux sesamoid fracture, had a history of prior foot surgery, or had medical records inadequate for analysis, 2) had missing or unclear diagnostic imaging, 3) were age >21 years, or 4) did not report sports participation. Descriptive statistics were employed to analyze the data.Results: Fifty-eight patients (51 females and 7 males) with a mean age of 15.4 years (range: 9-21) were identified with a total of 59 sesamoid fractures. Dancing (37.9%), running (13.8%), and gymnastics (13.8%) were the most common sports reported among these patients. A greater number of fractures were classified as repetitive stress injuries (83.1%), rather than acute traumatic injuries (16.9%). Fractures were treated conservatively in the majority of cases (89.8%), and only six fractures (10.2%) were treated surgically. Most patients (84.7%) were able to return to sports and activities. The average time from diagnosis/start of treatment to pain-free state/cleared to return to sport was 161.4 days.Conclusion: Diagnosis of sesamoid fractures can be challenging, but overall most patients do well with conservative treatment and are able to return to sports and activities. Providers should keep sesamoid fracture in the differential when evaluating patients with pain in the area around the base of the first toe, especially in dancers, gymnasts, and runners. Understanding that the recovery from a sesamoid fracture can be a prolonged process may help patients develop realistic expectations.

Factors influencing medial sesamoid arthritis in patients with hallux valgus deformity: Magnetic resonance imaging evaluation.

BACKGROUND: The importance of preoperative evaluation of the position and degree of arthritic changes of the medial sesamoid bone before hallux valgus correction is emerging. This is an observational study to evaluate the magnetic resonance imaging (MRI) findings of hallux valgus deformity, and assess the severity of and identify the factors that influence the arthritic changes in medial sesamoid-metatarsal (mSM) joints. METHODS: We reviewed weight-bearing anteroposterior radiographs, forefoot axial radiographs and MR images of 514 feet of 405 patients who underwent hallux valgus correction. On MRI, the degrees of the arthritic changes in the first metatarsophalangeal (MTP) and mSM joints were categorized into 5 classes. Binary logistic regression analysis was performed to identify the factors affecting the arthritic changes. RESULTS: The binary logistic regression analysis showed that advanced age, more lateralized position of medial sesamoid bone on forefoot axial radiograph, and higher MRI grade of arthritic change of the 1st MTP joint were significant factors contributing to medial sesamoid arthritis (P<0.001, 0.001. 0.006, respectively). CONCLUSIONS: Medial sesamoid arthritis can be assessed using MRI. The position of medial sesamoid bone on forefoot axial radiographs can strongly help predict the possibility of mSM joint arthritis. LEVEL OF EVIDENCE: III, observational study.