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.

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.

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.

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.

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.

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.

The fabella syndrome - a rare cause of posterolateral knee pain: a review of the literature and two case reports.

BACKGROUND: The purpose of this article was to evaluate the risks and benefits of non-operative treatment versus surgical excision of a fabella causing posterolateral knee pain. We performed a systematic review of literature and also present two case reports.Twelve publications were found in a PubMed literature review searching the word "fabella syndrome". Non-operative treatment and surgical excision of the fabella has been described. CASE PRESENTATION: Two patients presented to our outpatient clinic with persisting posterolateral knee pain. In both cases the presence of a fabella was identified, located in close proximity to the posterolateral femoral condyle. All other common causes of intra- and extra articular pathologies possibly causing the posterolateral knee pain were excluded.Following failure to respond to physiotherapy both patients underwent arthroscopy which excluded other possible causes for posterolateral knee pain. The decision was made to undertake surgical excision of the fabella in both cases without complication.Both patients were examined 6 month and one year after surgery with the Tegner activity score, the Visual Analogue Scale (VAS), and International Knee Documentation Committee Score (IKDC). CONCLUSION: Consistent posterolateral pain during exercise might indicate the presence of a fabella syndrome. Resecting the fabella can be indicated and is a minor surgical procedure with minimal risk. Despite good results in the literature posterolateral knee pain can persist and prevent return to a high level of sports. LEVEL OF EVIDENCE: IV, case reports and analysis of literature.

Comparison of histopathological and biomechanical changes of ligamentum mucosum in patients with anterior cruciate ligament rupture.

OBJECTIVES: The aim of this study was to identify the biomechanical and histopathological changes of ligamentum mucosum (LM) in patients with intact versus ruptured anterior cruciate ligament (ACL). PATIENTS AND METHODS: A total of 67 patients (45 males, 22 females; mean age: 33.2±7.9 years; range, 18 to 45 years) who underwent arthroscopic knee surgery for intraarticular pathologies between July 2022 and January 2023 were prospectively analyzed. The patients with LM were divided into two groups as the ACL intact group (n=31) and ACL ruptured group (n=36). Biomechanical tests and histopathological examinations were performed in all LM patients. RESULTS: Age and body mass index distributions were similar between the groups (p>0.05). Peak force values of the LM in the ACL ruptured group were significantly higher than the ACL intact group (p=0.037). No significant difference was found between the groups in terms of collagen index (p=0.103) and fibroblast count (p=0.821). CONCLUSION: The peak force values of the LM were significantly higher in the ACL ruptured group as compared to the ACL intact group, which is probably due to the adaptation of LM in patients with ACL rupture against increased deforming forces to maintain knee stability.

Articular chondral damage of the first metatarsal head and sesamoids: analysis of cadaver hallux valgus.

BACKGROUND: Evidence of successful correction on postoperative hallux valgus imaging studies may not always correlate with patient satisfaction. Recent attention to the association of cartilaginous degeneration and hallux valgus may provide new insight into treatment algorithms and patient expectations. The purpose of this cadaveric study was to evaluate the degree of chondral damage as it relates to increasing hallux valgus deformity. METHODS: A total of 39 cadaver first metatarsophalangeal joints were evaluated by radiography, and then dissected to evaluate for chondral damage. Chondral lesion grade, size, and location were recorded and then analyzed based on patient demographics and hallux valgus angle. RESULTS: Twenty-nine of 39 specimens were considered to have hallux valgus characterized by a hallux valgus angle of 15 degrees or greater. Four of 39 (10%) specimens revealed absence of chondral lesions, and 3 of those were found in the group with a hallux valgus angle of less than 15 degrees. Chondral lesions of increasing size and grade were seen more commonly with a more severe hallux valgus deformity. Particular locations on the metatarsal head appeared to be more prone to cartilaginous lesions when compared to other locations. CONCLUSION: Assessment of first metatarsophalangeal joint articular damage with regard to hallux valgus may be an important clinical parameter for consideration. CLINICAL RELEVANCE: Operative intervention to realign the first metatarsophalangeal joint may correct malalignment and relieve pressure on the widened forefoot, but residual pain within the joint may emanate from preexisting articular cartilaginous lesions. These findings support the concept that earlier intervention with operative realignment of a hallux valgus deformity and specifically the sesamoid complex may diminish degenerative changes.

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).

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.

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.

Catastrophic biaxial proximal sesamoid bone fractures in UK Thoroughbred races (1999-2004): horse characteristics and racing history.

REASON FOR PERFORMING STUDY: Catastrophic biaxial proximal sesamoid bone fractures (PSBF) have not yet been described in detail in the UK racing population. OBJECTIVES: To determine the incidence and relative risk (RR) of PSBF in different types of racing in the UK; and to describe horse-level characteristics and racing histories of horses sustaining these injuries. METHODS: Distal limbs were collected from all racehorses suffering catastrophic fractures during racing at all 59 racecourses in the UK, in a prospective study from February 1999 to December 2004. Post mortem investigation identified the anatomical location and type of fracture. Horse, racing history, race and racecourse details were obtained. Characteristics of the horses that sustained PSBF were described. The incidence and RR of PSBF in the different types of racing in the UK were calculated. RESULTS: Thirty-one horses suffered PSBF during the study period. The incidence of PSBF in all types of race was 0.63 per 10,000 starts (31/494,744). The incidence was highest in flat races on all weather surfaces (1.63 per 10,000 starts: 12/73,467; RR = 4.4 when compared to turf flat racing). Affected horses had an average age of 5.6 years and had started a mean of 28 races at the time of fracture. CONCLUSION AND POTENTIAL RELEVANCE: There is a strong association between type of racing surface and PSBF. Horses competing in flat races on all weather surfaces have an increased risk of PSBF. These fractures appear to happen in experienced horses with several starts, with few fractures occurring within the first season of racing. Further research should focus on identification of underlying pathology of these fractures. Epidemiological studies aimed at the identification of risk factors for PSBF in the UK racing population would require a large number of cases acquired over many years given the relatively low incidence of PSBF.

Determination of the prevalence and severity of metacarpophalangeal joint osteoarthritis in Thoroughbred racehorses via quantitative macroscopic evaluation.

OBJECTIVE: To determine the prevalence and severity of osteoarthritis in the metacarpophalangeal joints of Thoroughbred racehorses via development and validation of a quantitative macroscopic evaluation system. SAMPLE POPULATION: Metacarpophalangeal joints from 50 Thoroughbred racehorses. PROCEDURES: Joints were collected from horses that died or were euthanized within 60 days of racing. Metacarpophalangeal joints were assessed for osteoarthritic degeneration by use of macroscopic and histologic scoring systems, polarized light microscopy, and cartilage biochemical analysis. The global macroscopic score for the entire metacarpophalangeal joint was based on factors that reflected the size and severity of lesions as well as the involvement of weight-bearing surfaces. RESULTS: One-third of all 2- and 3-year-old horses had partial-or full-thickness cartilage lesions and osteoarthritis. Osteoarthritis severity increased until age 6 in this population. Significant correlations were found between macroscopic grade and age, cause of death, glycosaminoglycan depletion, and loss of superficial cartilage zone polarized light intensity. CONCLUSIONS AND CLINICAL RELEVANCE: The macroscopic system devised for this study had good correlations with quantitative methods. Two-and 3-year-old horses had full-thickness cartilage lesions that may have been career limiting. Year-to-year attrition and a small population of older horses may have led to underestimation of the prevalence of osteoarthritis in older horses. The macroscopic scoring system was reliable when used by nonexpert and expert users.

Degenerative disease of the distal interphalangeal joint and sesamoid bone in calves: 9 cases (1995-2004).

OBJECTIVE: To evaluate the clinical signs, diagnosis, treatment, and outcome associated with distal interphalangeal joint (DIJ) degenerative disease in calves. DESIGN: Retrospective case series. ANIMALS: 9 calves with degenerative disease of the DIJ. PROCEDURES: Medical records of calves with lameness for which the cause had been localized to the distal aspect of a limb but without evidence of trauma or sepsis were included. Signalment and results of physical, lameness, radiographic, and postmortem examinations were recorded. Outcomes of medical and surgical treatments were evaluated. RESULTS: All 9 calves had forelimb lameness (4 bilaterally). The medial digit was affected in 12 limbs and the lateral digit was affected in 9 limbs. Radiographic examination revealed bridging osteoproliferation along the abaxial and palmar aspects of affected DIJs (18/21), subchondral cyst-like lucencies (19/21), and sclerosis (16/21). The DIJ was resected in 3 calves (7 joints), resulting in resolution of lameness within 3 months. Medical management was attempted in 4 calves (6 joints), and 2 calves (6 joints) did not receive treatment; 5 calves had a normal stance within 5 months. Results of postmortem computed tomographic and histologic examination were in accordance with degenerative joint disease processes. CONCLUSIONS AND CLINICAL RELEVANCE: Degenerative disease of the DIJ should be considered in calves with insidious, progressive forelimb lameness. Although the etiology of this process remains undetermined, results of radiographic, computed tomographic, and histologic examinations suggested an underlying developmental anomaly, such as osteochondrosis. Surgical treatment appeared promising on the basis of postoperative resolution of lameness in all surgically treated calves.

A radiologic and histologic study of the os peroneum: prevalence, morphology, and relationship to degenerative joint disease of the foot and ankle in a cadaveric sample.

The present study investigated the prevalence of an os peroneum (OP, a sesamoid bone) in a cadaveric sample and its relationship to the shape of the cuboid tuberosity, and cartilage degeneration at the cuboid tuberosity and in regional joints within the foot (first metatarsophalangeal and calcaneocuboid) and ankle. The fibularis longus tendon of 33 embalmed human cadavers (mean age 81 years) were obtained from the anatomy laboratory. Nineteen of 64 tendons (30%) displayed an OP both radiographically and histologically. The os peronei ranged in size from small spicules to prominent masses: mean area 2.48 mm(2) (left) and 2.70 mm(2) (right). Histologically, the os peronei were cancellous bone, the largest occupying most of the tendon at the point of contact with the cuboid tuberosity. Fibrocartilage was present at their borders, merging with dense regular fibrous tissue and peritenon. The talocrural, calcaneocuboid, and first metatarsophalangeal joints were examined for cartilage integrity and osteophytes based on an earlier suggestion that there may be an association between degenerative joint disease and endochondral bone formation. There was no statistical correlation between presence of an OP with any of the following parameters: age, gender, body size, cartilage degeneration, or osteophytes within any of the joints examined. Therefore, the presence of an OP does not appear to be associated with increased endochondral ossification or degenerative joint disease. This study does not preclude the possibility that sesamoid bone formation may be associated with biomechanical functions within the foot; thus, future studies may be warranted.

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.

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.

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.