Proximal sesamoid bone microdamage is localized to articular subchondral regions in Thoroughbred racehorses, with similar fracture toughness between fracture and controls.

OBJECTIVE: To determine whether proximal sesamoid bone (PSB) microdamage and fracture toughness differ between Thoroughbred racehorses sustaining PSB fracture and controls. STUDY DESIGN: Cadaveric case-control. ANIMALS: Twenty-four Thoroughbred racehorses (n = 12 PSB fracture, n = 12 control). METHODS: Proximal sesamoid bones were dissected, and gross pathological changes and morphological measurements were documented. High-speed exercise history data were evaluated. Microdamage was assessed in fracture, fracture-contralateral limb (FXCL) and control PSBs using whole bone lead uranyl acetate (LUA) staining with micro-CT imaging or basic fuchsin histological analysis. Fracture toughness mechanical testing was carried out in 3-point-bending of microbeams created from PSB flexor cortices. Data were analyzed using ordinal logistic and linear regression models. RESULTS: Microdamage was detected most commonly in the articular subchondral region of PSBs via LUA micro-CT and basic fuchsin histology. There were no differences in microdamage between FXCL and control PSBs. Fracture toughness values were similar for FXCL (1.31 MPa√m) and control (1.35 MPa√m) PSBs. Exercise histories were similar except that horses sustaining fracture spent a greater percentage of their careers in rest weeks. CONCLUSION: Microdamage was detected in the articular region of PSBs but was not greater in horses sustaining catastrophic PSB fracture. Fracture toughness of PSB flexor cortices did not differ between FXCL and control PSBs. CLINICAL SIGNIFICANCE: Although uncommon, microdamage is localized to the articular region of Thoroughbred racehorse PSBs. Catastrophic PSB failure is not associated with lower PSB flexor cortex fracture toughness.

Exercise history predicts focal differences in bone volume fraction, mineral density and microdamage in the proximal sesamoid bones of Thoroughbred racehorses.

Medial proximal sesamoid bones (PSBs) from Thoroughbred racehorses that did (Case) or did not (Control) experience unilateral biaxial PSB fracture were evaluated for bone volume fraction (BVF), apparent mineral density (AMD), tissue mineral density (TMD), and microdamage in Case fractured, Case contralateral limb intact, and Control bones. A majority of Case bones had a subchondral lesion with high microdamage density, and low BVF, AMD, and TMD. Lesion microdamage and densitometric measures were associated with training history by robust linear regression. Exercise intensity was negatively related to BVF (0.07 ≤ R2 ≤ 0.12) and positively related to microcrack areal density (0.21 ≤ R2 ≤ 0.29) in the lesion; however, in an undamaged site, the relationships were opposite in direction. Regardless of location, TMD decreased with event frequency for both Case and Control, suggesting increased bone remodeling with exercise. Measures of how often animals were removed from active training (layups) predicted a decrease in TMD, AMD, BVF, and microdamage at regions away from the lesion site. A steady-state compartment model was used to organize the differences in the correlations between variables within the data set. The overall conclusions are that at the osteopenic lesion site, repair of microdamage by remodeling was not successful (e.g., lower bone mass, increased damage, and lower mineralization) but that in regions away from the lesion remodeling successfully controlled damage (e.g., higher bone mass, less microdamage, and lower mineralization).

Sudden death caused by spinal cord injury associated with vertebral fractures and fetlock failure in a Thoroughbred racehorse.

The most prevalent causes of death in racehorses are musculoskeletal injuries, causing ~83% of deaths within the racing industry in California and elsewhere. The vast majority of these injuries have preexisting lesions that predispose to fatal injury. A 4-y-old Thoroughbred colt suffered an acute suspensory apparatus failure, including biaxial proximal sesamoid bone fractures of the right front fetlock, causing loss of support of the fetlock joint and consequent fall with fractures of the cervical and sacral spine. Cervical fracture caused spinal cord damage that resulted in sudden death. A preexisting lesion in the medial proximal sesamoid bone likely predisposed to complete fracture of this bone and fetlock breakdown. Interestingly, a comparable osteopenic lesion was present in the intact medial proximal sesamoid bone of the left forelimb, which is consistent with bilateral repetitive overuse injury in racehorses. The morphologic features of the cervical and sacral spine fractures were compatible with acute injury; no evidence of preexisting lesions was seen. Most likely, these acute vertebral fractures occurred as a result of the horse falling. This case emphasizes the importance of performing a detailed autopsy in horses that suffer an appendicular musculoskeletal injury, particularly in fatal cases when the horse dies following a leg injury.

High Prevalence of Degenerative Changes at the Metatarsal Head Sesamoid Articulation Found During Hallux Valgus Correction Surgery.

Background. Despite the absence of complications and a restoration of normal hallux alignment, some patients have suboptimal outcomes from hallux valgus correction surgery. One risk factor for persistent pain may be the presence of arthritic changes at the metatarsal head articulation with the sesamoids, an area not easily assessed with standard radiographs unless dedicated sesamoid views are obtained. In this study, we prospectively evaluated the metatarsal head for degenerative changes during hallux valgus correction surgery and identified preoperative risk factors associated with these changes. Methods. We prospectively evaluated 200 feet in 196 patients who underwent hallux valgus surgery intraoperatively for the pattern and severity of arthritic changes at the metatarsal head. Mann-Whitney U testing was implemented to compare differences in arthritic scores between preoperative deformity groups. The Spearman correlation test was used to determine the association between age and preoperative deformity with the severity of degenerative changes. Results. More than half of all feet assessed had severe arthritic changes at the plantar medial aspect of the metatarsal head and 40% of feet at the plantar lateral aspect. Age and intermetatarsal angle were found to be positively correlated with arthritis in this area. Conclusion. Our prospective study has demonstrated the high prevalence of arthritic changes at the metatarsal head sesamoid articulation and the positive influence of age and severity of deformity on metatarsal head arthritic changes seen during hallux valgus correction surgery. Furthermore, these arthritic changes were found to have no significant influence on preoperative functional and pain levels.Levels of Evidence: Level IV: Case series.

Fabellar prevalence, degeneration and association with knee osteoarthritis in the Chinese population.

The fabella is a sesamoid bone of the knee that can degenerate in some patients with osteoarthritis. The purpose of this study was to examine the prevalence and degeneration grades of fabellae in the Chinese population and to analyse their relationships with subject ages and knee osteoarthritis grades. The anteroposterior and lateral knee roentgenograms of 1150 subjects were recruited from the institutional database. The Kellgren-Lawrence scoring system was used to evaluate knee osteoarthritis. The degeneration grades of fabellae were scored in lateral roentgenograms by screening their shapes, sizes, subchondral sclerosis and osteophyte formation. The prevalence and degeneration of fabellae among ages, genders and knee sides were analysed by the Pearson Chi-Square test, and their relationships with knee osteoarthritis were analysed by the Spearman nonparametric correlation test. The overall prevalence of fabellae was 48.6% in 1359 knees. There was no significant difference in fabellar prevalence between the two sides (χ² = 0.025, P = 0.87437) and genders (χ² = 3.647, P = 0.05617), while the prevalence increased with the increasing ages of the subjects (χ² = 213.868, P < 0.001). The fabellar degeneration grades were correlated with age (r = 0.5288, P < 0.001) and knee osteoarthritis scores (r = 0.6892, P < 0.001). These results suggested that the fabellar prevalence and degeneration grades were correlated with age and knee osteoarthritis scores.

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.

Comparative Stiffness of an Equine Distal Sesamoid Bone Fracture Model Stabilized with 3.5-mm versus 4.5-mm Cortical Bone Screws in Lag Fashion.

OBJECTIVE: The aim of this study was to to determine the comparative stiffness following repair of an axial sagittal fracture model in equine distal sesamoid bones using either a single 3.5-mm or 4.5-mm cortical bone screw placed in lag fashion. STUDY DESIGN: The present study was an in vitro biomechanical study. RESULTS: The mean (±standard deviation) stiffness value for the 4.5-mm screw-bone construct (522.49 N/mm ± 168.21) was significantly greater than the 3.5-mm screw-bone construct (408.46 N/mm ± 131.13) (p = 0.047). This represents a 28% difference in mean stiffness. CONCLUSIONS: In vitro, the 4.5-mm screw-bone construct creates a stiffer repair of fractured distal sesamoid bones by a margin of 28%. The 4.5-mm cortical bone screw may better withstand forces imparted on the distal sesamoid bone sustained during anaesthetic recovery, normal weight bearing and athletic exercise, thereby minimizing the risk of implant failure.

Avascular Necrosis of the Sesamoids.

Avascular necrosis (AVN) of the sesamoid is pathology of the medial or lateral hallucal sesamoid resulting in pain under the first metatarsophalangeal joint often presenting in young female athletes. There is overlap of stress fracture, nonunion, and AVN that makes defining the diagnosis difficult but the treatment and outcomes are similar. The most reliable operative treatment used for AVN of the sesamoid is an accumulation of anatomic and mechanical factors with repetitive microtrauma. Nonoperative modalities are designed to offload the sesamoid. The only operative treatment used for AVN of the sesamoid is excision of the involved bone, which results most commonly in complete patient satisfaction.

Effect of sesamoid position on functional outcome of operated hallux valgus.

INTRODUCTION: The loss of correct relationships between the sesamoid and the first metatarsal is one of the architectural consequences of the hallux valgus (HV). The reduction of this dislocation by lateral soft tissue release (LSTR) is one of the objectives of surgery. AIM: To study the relationship between postoperative position of sesamoid and clinical outcome at one-year postoperative follow-up. METHODS: It's a retrospective study including patients operated for evolved HV performed in la Rabta orthopedic department in Tunis. These patients had a Scarf osteotomy associated with at least one Weil osteotomy. The functional evaluation was based on the AOFAS score (American-orthopedic-foot-and-ankle-society). We classified the sesamoid position according to 3 scores: Hardy & Clapham , RCAOFAS and the Agrawal. We compared each score of the sesamoid position to the clinical outcome. RESULTS: We collected 46 cases of HV in 45 patients. The mean AOFAS score increased from 60,9 to 85,5/100 postoperatively. Our patients were divided into 2 groups: group A whose result was excellent and group B whose result was good, fair and poor. The analytical study of this work concluded that there was no relationship between the postoperative sesamoid position and the clinical outcome, regardless of the radiological classification used (p=0,361, p=0,222, p=0,260). CONCLUSION: Sesamoids that remain in postoperative dislocation are not necessarily predictive of a poor clinical outcome at one year of the surgical cure.

Oblong Sesamoid Bone Appearance into the Nuchal Ligament. A Case Report.

Radio-opaque formations behind the spinous processes of the cervical spine are really rare. They were described in 1929 for the first time. Sesamoid ossicles are found close to a bone or a joint and are usually small. Some sesamoids form part of normal human anatomy, while others are normal anatomical variants. We report a case of a 73-year-old Caucasian male who visited the outpatient clinic complaining about chronic cervical pain. An oblong sesamoid accidentally discovered during routine anteroposterior (AP) and lateral x-ray, within the nuchal ligament (NL) at the C3-C6 spinous processes level. A cervical MRI scan was performed and the result showed 'fabella nuchae'. This type of sesamoids are rarely symptomatic, but it should be differentially diagnosed anyway. We review its morphology, the mechanical factors of the region acting throughout life and last, but not least, the differential diagnosis.

Effect of metatarsal osteotomy and open lateral soft tissue procedure on sesamoid position: radiological assessment.

BACKGROUND: Incomplete sesamoid reduction is a potential risk factor for the recurrence of hallux valgus. The purpose of this study was to radiologically investigate changes in sesamoid position after chevron osteotomy and the open lateral soft tissue procedure. METHODS: Sixty-eight feet that underwent operative correction for hallux valgus deformity were reviewed consecutively. The hallux valgus angle (HVA), first to second intermetatarsal angle (IMA), tibial sesamoid position (TSP), distance of the fibular sesamoid (DFS), and translation of the metatarsal head (TMH) were evaluated preoperatively and at final follow-up. RESULTS: While most parameters were significantly decreased after surgery, no significant change in DFS (correction - 1.45 mm, p = 0.08) was noted. The difference between preoperative and postoperative TSP values (ΔTSP) has a moderately positive correlation with difference in TMH values (ΔTMH) (Rho 0.475, p = .000). Other parameters were similarly correlated. CONCLUSIONS: First, metatarsal bone realignment reduced the sesamoid, but its position, relative to the second metatarsal axis (DFS), was unchanged. The sesamoid is reduced by the lateral translation of the first metatarsal but not by medial sesamoid migration.

Foal Fractures: Osteochondral Fragmentation, Proximal Sesamoid Bone Fractures/Sesamoiditis, and Distal Phalanx Fractures.

Foals are susceptible to many of the same types of fractures as adult horses, often secondary to external sources of trauma. In addition, some types of fractures are specific to foals and occur routinely in horses under 1 year of age. These foal-specific fractures may be due to the unique musculoskeletal properties of the developing animal and may present with distinct clinical signs. Treatment plans and prognoses are tailored specifically to young animals. Common fractures not affecting the long bones in foals are discussed in this article, including osteochondral fragmentation, proximal sesamoid bone fractures/sesamoiditis, and distal phalanx fractures.

Osteochondroma of the Tibial Sesamoid: A Case Report and Review of the Literature.

Osteochondroma, one of the most common benign bone tumors, frequently occurs in the metaphysis of the long bones. We report an extremely rare case of osteochondroma that occurred in the tibial sesamoid. The patient was a 62-year-old Japanese male. He presented with a 1-year history of pain and a hard mass on the plantar aspect of the right forefoot sole. The osteochondroma protruded toward the sole from the tibial sesamoid, leading to pain on weightbearing. After tibial sesamoidectomy, the patient's symptoms were eliminated, and no pain or complications such as hallux valgus occurred after the surgery. Although a potential risk exists of postoperative hallux valgus deformity, tibial sesamoidectomy seems to be an appropriate surgical option for both osteochondroma and bizarre parosteal osteochondromatous proliferation to avoid residual pain or local recurrence.

18F-NaF PET-CT in Symptomatic Fabella Syndrome.

Fabella is a sesamoid bone, located within the tendon of the lateral head of the gastrocnemius muscle. It may be associated with posterolateral knee pain because of repetitive friction over the posterolateral femoral condyle. We report a case of a 64-year-old woman presenting with right posterolateral knee pain. F-NaF PET-CT demonstrated increased uptake posterior to the right knee joint localizing to a fabella. Standard examination and radiographic imaging excluded other causes for posterolateral knee pain, and the increased activity was considered to be secondary to fabella syndrome. NaF PET-CT can provide useful information in the evaluation of posterolateral knee pain.

[Morphology characteristics of sural bean bone and it's role in knee joint diseases].

Fabella is a common sesamoid bone. In recent years, people have paid more attention to its anatomic location, distribution characteristics in crow, importance in stabilizing knee joint and related diseases. This article reviews the anatomy, distribution and the relationship between the calf bone and the knee joint diseases, so as to strengthen the attention of the bones in the diagnosis and treatment of knee diseases.

Relationship Between Displacement and Degenerative Changes of the Sesamoids in Hallux Valgus.

BACKGROUND: Although the tangential sesamoid view is used to visualize the sesamoid position relative to the first metatarsal head, correctly evaluating patients with severe varus of the first metatarsal is difficult. Computed tomography (CT) can be helpful due to its cross-sectional images in any plane. The purposes of this study were to evaluate the alignment of the tibial sesamoid and investigate the relationship between malalignment and degenerative change in the sesamoid metatarsal joint (SMJ) using simulated weight-bearing CT imaging in patients with hallux valgus. METHODS: In total, 269 feet from 142 patients with hallux valgus were included. The mean age was 63.7 years (range, 33-87 years). An anteroposterior weight-bearing radiograph was assessed for sesamoid position into 3 grades: grade 1, the tibial sesamoid was medial to the axis of the first metatarsal; grade 2, the tibial sesamoid was located below the first metatarsal axis; and grade 3, the tibial sesamoid was lateral to the first metatarsal axis. The hallux valgus and intermetatarsal angles (HVA and IMA, respectively) were measured. The lateral shift of the tibial sesamoid relative to the first metatarsal was classified into 3 grades on simulated weight-bearing CT classification: grade 1, tibial sesamoid was entirely medial to the intersesamoid ridge; grade 2, tibial sesamoid was subluxated laterally but located below the intersesamoid ridge; and grade 3, tibial sesamoid was located entirely lateral to the intersesamoid ridge. The differences of HVA and IMA in each grade were confirmed by using 1-way analysis of variance with Bonferroni post hoc corrections. Furthermore, multiple linear regression analysis was used to predict the degenerative change in the SMJ for age, sex, sesamoid position determined by CT or plain radiography, HVA, and IMA. The χ2 test was used for descriptive statistics to analyze the agreement between radiography or CT classifications of sesamoid position against degenerative change in the SMJ. RESULTS: Based on the radiographic classification of the tibial sesamoid position, 7 feet were classified as grade 1, 72 were grade 2, and 190 were grade 3, respectively. Based on the CT classification, 34 feet were classified as grade 1, 116 were grade 2, and 119 were grade 3. Degenerative change in SMJ progressed according to the sesamoid shift relative to the first metatarsal using either radiography or CT. In radiography, statistically significant differences were found except for the difference in HVA between grades 1 and 2. In addition, statistically significant differences were found between HVA and IMA, along with the grades in CT.In multiple linear regression, degenerative change was correlated with age and sesamoid position in CT and radiographic classifications. CONCLUSION: Our study showed that lateral shift of the tibial sesamoid increased in association with progression of the hallux valgus deformity. Furthermore, increasing lateral shift of the tibial sesamoid was associated with worsening degenerative change within the SMJ. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

The Hallucal-Sesamoid Complex: Normal Anatomy, Imaging, and Pathology.

The first metatarsophalangeal joint and hallucal-sesamoid complex are critical structures in weightbearing and susceptible to several pathologies including turf toe, sesamoiditis, degenerative or inflammatory arthritides, infection, and avascular necrosis. This review article summarizes the complex anatomy of the region, covers common pathologies while clarifying terms such as turf toe and sesamoiditis, reviews imaging techniques, and discusses management.

Gout Causing Isolated Sesamoid Destruction Mimicking a Neoplastic Process.

The hallux metatarsophalangeal joint (MTPJ) is a common location affected by gouty inflammatory arthritis. Generally, this condition is successfully treated with medication and regular surveillance. Occasionally, gout can lead to advanced arthritic changes and chronic discomfort of the hallux MTPJ, necessitating surgical intervention to help alleviate symptoms. Rarely is the condition isolated to the sesamoid bone, which may lead to a diagnostic dilemma in patients without a history of gout. We report the case of a patient in whom isolated sesamoid changes associated with gout mimicked an aggressive neoplastic process.