Prediction models incorporating second metacarpal cortical index for osteoporosis in rheumatoid arthritis: Externally validated machine learning models developed using data from the KURAMA cohort.

OBJECTIVE: Osteoporosis and osteopenia are significant concerns in rheumatoid arthritis (RA), predisposing patients to fragility fractures. While dual-energy X-ray absorptiometry (DXA) is the gold standard for bone mineral density (BMD) assessment, simpler screening tools are needed. This study aims to assess the correlation between the second metacarpal cortical index (2MCI) and BMD in RA patients, and to evaluate machine learning (ML) models utilizing 2MCI and clinical parameters for predicting osteoporosis/osteopenia presence and BMD. METHODS: Data from the KURAMA cohort (n = 302) and an external validation cohort (n = 32) were analyzed. BMD in the hip and forearm was obtained using DXA and 2MCI was calculated from plain hand X-ray. ML models were trained to predict osteoporosis/osteopenia presence and BMD using 2MCI and clinical variables and validated using external cohort. RESULTS: 2MCI correlated significantly with hip and forearm BMD. ML models incorporating 2MCI and other clinical parameters showed good performance in predicting osteoporosis/osteopenia presence and BMD. External validation demonstrated the generalizability of the models. CONCLUSION: ML models utilizing 2MCI and clinical parameters show promise for osteoporosis screening in RA patients.

Surgical Management of a Delayed Presentation of Floating First Metacarpal with Multiple Fracture Dislocations: A Case Report.

CASE: A 23-year-old man presented with a 2-month-old injury involving a volar base metacarpal fracture dislocation of carpometacarpal joint (CMC), metacarpophalangeal joint (MP) dislocation, floating metacarpal, and proximal phalanx base fracture. Treatment involved open reduction of volar base metacarpal's fracture and CMC dislocation, MP joint reduction, collateral ligament repair, and proximal phalanx fixation with plates and screws. A modified Eaton-Littler procedure with flexor carpi radialis tendon enhanced CMC joint stability. At 6 weeks, fractures had healed well, achieving good thumb motion. One-year follow-up showed no arthritis or dislocation. CONCLUSION: Thumb injuries are relatively common and can involve complex fractures and dislocations. Open reduction of the delayed fractures, dislocations, and ligament repair and reconstruction can lead to successful outcome.

Postoperative Radiographic Outcomes Following Abduction-Extension Metacarpal Osteotomy: A Comparison between Early and Advanced Carpometacarpal Arthritis.

Background: This study aimed to investigate the effect of thumb metacarpal osteotomy on dorsal subluxation of the carpometacarpal (CMC) joint and compare the effects of early and advanced osteoarthritis (OA). Methods: We retrospectively reviewed 42 thumbs of 37 patients who underwent metacarpal osteotomy with a postoperative extension angle of 90° or more between January 2018 and October 2021 and were followed up for more than 2 years. The thumbs were classified into two groups: early OA (Eaton stage I or II) and advanced OA (Eaton stage III). We measured the reduction ratio, which was defined as the ratio of improvement in dorsal subluxation, at 3 months and 1 year postoperatively, and at the latest follow-up. We statistically compared the reduction ratio between the two groups and investigated the factors affecting the reduction ratio using correlation analysis. Results: The reduction ratio was significantly higher in the early OA group than in the advanced OA group at 3 months after surgery, whereas no significant difference was found between the two groups at 1 year after surgery and at the latest follow-up. A significant positive correlation was detected between the reduction ratio and the postoperative extension angle. Conclusions: First metacarpal osteotomy reduces dorsal subluxation in both early- and advanced-stage CMC OA. This procedure yields immediate marked reduction in early-stage OA, while improvement of the subluxation progressed gradually in advanced-stage OA. Level of Evidence: Level IV (Therapeutic).

Validation of the Chicken Femur as a Model for the Human Metacarpal: An In-Vitro Analysis.

Background: The aim of this study was to evaluate the chicken femur as a laboratory model for the human metacarpal by comparing the bone microarchitecture and mechanical properties of chicken femurs to human cadaveric metacarpals. Methods: Sixteen fresh chicken femora and 20 fresh frozen cadaveric human metacarpals were imaged using a micro computed tomography scanner. The bones were then mechanically tested using four-point-bending and torsional testing. Results: There were no significant differences in macroscopic features between chicken femora and human metacarpals, including overall length, external radius, internal radius, cortical width and cross-sectional area of the diaphyseal cortex (p > 0.05). There were no significant differences in the trabecular number and spacing in the distal metaphysis of both groups (p > 0.05). The diaphysis and proximal metaphysis did not share any microarchitectural similarities. Four-point bending tests resulted in significantly higher yield forces, ultimate force, failure points and stiffness in human metacarpals (p < 0.05). Torsion tests resulted in significant higher ultimate torque and torsional rigidity in human metacarpals (p < 0.05). Conclusions: The chicken femur has structural and biomechanical differences to the fresh frozen human metacarpal despite the similarity in their macroscopic features.

Percutaneous transverse pinning for metacarpal fractures: a clinical trial.

INTRODUCTION: Metacarpal fractures account for 25%-50% of all hand fractures and may negatively impact hand function and ability to work. Percutaneous transverse pinning of non-articular metacarpal fractures allows mobilisation immediately after the procedure. METHODS: Between March 2017 and February 2022, 56 patients undergoing percutaneous transverse pinning for unstable metacarpal fractures were prospectively recruited. We investigated surgical outcomes in terms of Patient-rated Wrist/Hand Evaluation (PRWHE) and pre-and post-operative radiographic evaluation. The Student t-test was used to compare the means of PRWHE values after surgery. Statistical significance was set at p < 0.05. RESULTS: The mean age was 40.21 ± 17.9 years (range of 16 to 86 years). The average operating time was 27.96 min. The mean follow-up period was 14.3 ± 6.4 months (from 2 to 41 months). The mean PRWHE score was 6.5 ± 1.8. None of the patients had clinically observable rotational deformities, and the functional outcomes were satisfactory. CONCLUSION: Percutaneous transverse pinning for non-articular metacarpal fractures restores excellent function, and imaging results are satisfactory. Further high-quality clinical trials are required to validate these results on a larger scale. LEVEL OF EVIDENCE: II, prospective cohort study.

Radiomorphometric analysis of the metapodial bones in the Scottish fold cats.

Scottish Fold cats (Felis catus, Linnaeus 1758) are one of the most well-known and popular cat breeds in the world, characterized by their folded ears attached to the head. Very frequently, cats fall prey of different trauma and accidents that can cause bone fractures especially in the metapodial bones. The method of radiometry is used in veterinary practice to visualize and measure different parts of the animal skeleton. The aim of this study was to assess the linear parameters derived from radiographic images of the metacarpals and metatarsals in Scottish Fold cats and additionally detecting potential sexual dimorphism. Radiographic images of 24 adult Scottish Fold cats (12 male and 12 females) of different ages and weights were analysed. Six linear measurements of the metapodial bones were evaluated to investigate any differences between the sexes. The linear radiometric measurements of the five metacarpals (MC1-5) and the four metatarsals (MT2-5) bones were larger in male metapodial bones than that of female cats. The maximum length (Ml) of the MC1 and MC2 was statistically different between sex, respectively, (p = 0.001) and (p = 0.05). The others metacarpal bones were different in mostly all linear parameters but not statistically significant. The most significant differences between sexes were observed in the parameter of width proximal end (Wp) of MC1-3 (p = 0.001) and MC4 (p = 0.05). More statistical different was MT2 and less MT3. The linear parameter of Bd of the MT4 was the most different statistically between sex (p = 0.001). The results of the study will be useful in function of comparative anatomy, in veterinary clinical practice, in zoo archaeology and in the veterinary forensic investigation.

Metal hypersensitivity in trapeziometacarpal arthroplasty: A systematic pattern of progression.

Metal hypersensitivity is a rare and often underestimated complication, as shown by the small number of published studies, particularly concerning the upper limbs and the hand. However, the increase in the annual number of trapeziometacarpal arthroplasties underlines the importance of better understanding of this problem. We performed a study based on data from the revision of trapeziometacarpal prostheses to assess the incidence of this complication and to define a sequence of radiological changes to detect metal hypersensitivity. This single-center retrospective study included 37 patients operated on between January 2014 and November 2023 for revision of trapeziometacarpal prosthesis. Ten (27%) had no clearly identified cause of failure. For these 10 patients, we analyzed clinical data and postoperative X-rays. In the 11 revision arthroplasties, 2 patients had no symptoms or radiographic signs suggestive of allergy. Six patients had a-posteriori diagnosis established by allergy testing, which also identified 2 additional patients, for a total of 8 patients (21% of the initial cohort). In these cases, there was systematic metaphyseal osteolysis of the first metacarpal between 15 days and 1 month after implantation. Clinically, most patients had an asymptomatic period of 2 weeks to 1 month before onset of symptoms and osteolysis, often accompanied by local inflammation. This study found a reproducible pattern of progression, characterized by the appearance of radiographic signs of osteolysis in the first month, followed by clinical deterioration. Although this course is strongly suggestive of a metal hypersensitivity, it is crucial not to exclude the possibility of an infectious cause, which should always be considered.

MAÏA Trapeziometacarpal Joint Arthroplasty: Clinical and Radiological Outcomes of 76 Patients With More Than 10 Years of Follow-Up.

PURPOSE: Trapeziometacarpal (TMC) joint replacement has become a valid option in the therapeutic arsenal of TMC joint osteoarthritis in Europe. Good mid-term results of the MAÏA TMC joint prosthesis suggested that it is a reliable procedure. This study aimed to assess the long-term results of this modular uncemented ball-and-socket hydroxyapatite-coated implant. METHODS: This single-center retrospective study evaluated 92 MAÏA TMC joint prostheses in 76 patients with a minimum of 10 years of follow-up. Indications for the procedure were painful TMC joint osteoarthritis both at rest and during activity, despite nonsurgical treatment for more than six months. Pre- and postoperative clinical and radiographic outcomes were compared. RESULTS: Mean follow-up was 134 months (range: 120-158 months). Mean age at the time of surgery was 67 years (range: 53-84 years). The cohort comprised 86.8% of women (n = 66). The mean Quick Disabilities of the Arm, Shoulder, and Hand score improved from 61.3 ± 17.1 to 19.6 ± 16. Range of motion was restored, and postoperative mobility was comparable with that of the contralateral side. Final Kapandji opposition score was almost normal (9.2 ± 0.7). Final key pinch and grip strength improved by 26% and 39%, respectively. Eight implants were surgically revised, six for trapezium cup loosening and two for instability because of polyethylene wear. Three cases of traumatic fracture of the trapezium in older patients were successfully treated with a cast for eight weeks. Five of 26 (20.8%) cases of preoperative-reducible z-deformity were not totally corrected after surgery. The Kaplan-Meier survival over 10 years was 88% (95% confidence interval: 84-93) versus 93% (95% confidence interval: 87-98) over 5 years. CONCLUSIONS: MAÏA TMC joint prosthesis is a reliable long-term surgical procedure for TMC joint osteoarthritis, improving overall function beyond 10 years. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Metacarpophalangeal hyperextension in trapeziometacarpal osteoarthritis: Relationship to first metacarpal head shape, and clinical impact.

PURPOSE: The aim of this study was to determine whether the shape of the first metacarpal head influences metacarpophalangeal hyperextension, and to evaluate the influence of metacarpophalangeal hyperextension on hand pain and function in patients with trapeziometacarpal osteoarthritis. METHODS: 362 patients with painful basal thumb osteoarthritis were evaluated over a 2-year period. Pain rating on a visual analog scale, trapeziometacarpal and metacarpophalangeal motion, and grip and pinch strength were evaluated. The shape of the metacarpal head was assessed on strict lateral radiographs using the "A/r" ratio. RESULTS: Round metacarpal heads had significantly greater and more frequent metacarpophalangeal hyperextension than flat heads (28° vs. 8°, and 78% vs. 29%). Metacarpophalangeal hyperextension adversely impacted trapeziometacarpal motion in antepulsion (27° vs. 32°), abduction (25° vs. 30°) and pinch strength (3.6 vs. 4.6 KgF). CONCLUSION: Our findings indicate that the shape of the metacarpal head influences metacarpophalangeal hyperextension in trapeziometacarpal osteoarthritis. Metacarpophalangeal hyperextension adversely impacted pinch strength and trapeziometacarpal motion. LEVEL OF EVIDENCE: Level IV, Retrospective case series.

Gender and age differences in the associations between cortical thickness and hand osteoarthritis severity: data from the Osteoarthritis Initiative.

OBJECTIVE: To evaluate gender differences in the association between metacarpal cortical thickness (Tcort)-a surrogate for bone density-and severity of radiographic hand osteoarthritis (HOA) in a longitudinal observational study. METHOD: Hand radiographs of 3575 participants (2039 F/1536 M) from the Osteoarthritis Initiative were assessed at baseline and 48 months. A reader used a semi-automated software tool to calculate Tcort, a measurement of the cortical thickness, for metacarpals 2-4. Average Tcort at baseline and change in Tcort from baseline to 48 months was determined and stratified by gender and age for 7 5-year age groups. Spearman's rank correlation coefficients were calculated for the association of baseline Tcort and 2 measures of baseline HOA severity: the sum of Kellgren-Lawrence (KL) grade and total number of joints with radiographic HOA. Longitudinally, logistic regression was used to assess the relationship of Tcort loss to new finger joint radiographic HOA, increase in KL grades, and incident hand pain. RESULTS: Male Tcort was higher than females. Significant correlations between Tcort and radiographic severity were noted for women but not men, with stronger associations among women >60 years (rho = -0.25; 95% confidence interval (CI) = -0.31 to -0.19). Statistically significant associations were seen between Tcort change and radiographic osteoarthritis change among women but not men, with substantial gender differences for Tcort change, particularly ages 50 to 70 years (p < 0.01; e.g., Tcort change ages 55 to <60: males = -0.182 (0.118), females = -0.219 (0.124)). CONCLUSION: We found significant HOA-related gender differences in Tcort, suggesting the involvement of female bone loss during and after menopause.

Subchondral bone fatigue injury in the parasagittal condylar grooves of the third metacarpal bone in thoroughbred racehorses elevates site-specific strain concentration.

Condylar stress fracture of the distal end of the third metacarpal/metatarsal (MC3/MT3) bones is a major cause of Thoroughbred racehorse injury and euthanasia worldwide. Functional adaptation to exercise and fatigue damage lead to structural changes in the subchondral bone that include increased modeling (resulting in sclerotic bone tissue) and targeted remodeling repair (resulting in focal resorption spaces in the parasagittal groove). Whether these focal structural changes, as detectable by standing computed tomography (sCT), lead to elevated strain at the common site of condylar stress fracture has not been demonstrated. Therefore, the goal of the present study was to compare full-field three-dimensional (3D) strain on the distopalmar aspect of MC3 bone specimens with and without focal subchondral bone injury (SBI). Thirteen forelimb specimens were collected from racing Thoroughbreds for mechanical testing ex vivo and underwent sCT. Subsequently, full-field displacement and strain at the joint surface were determined using stereo digital image correlation. Strain concentration was observed in the parasagittal groove (PSG) of the loaded condyles, and those with SBI in the PSG showed higher strain rates in this region than control bones. PSG strain rate in condyles with PSG SBI was more sensitive to CT density distribution in comparison with condyles with no sCT-detectable injury. Findings from this study help to interpret structural changes in the subchondral bone due to fatigue damage and to assess risk of incipient stress fracture in a patient-specific manner.

Morphological and radiographic studies on the Manus region in the Arabian one-humped camel (Camelus dromedaries).

The study aims to analyse the normal anatomical and radiographical features of the Manus of the southern Aswanian-adapted Arabian one-humped camel, providing crucial data for diagnosing and treating various ailments. Our study was applied to 10 cadaver forelimbs of adult male one-humped camels (4-5 years old) for an explanation of the gross anatomy of the bones of the Manus region from under the carpal bones by using traditional techniques, including the gross anatomical, radiographic and x-ray (at the dorsopalmar and lateral planes) of the preparation of Manus bones. Our results showed that the large fused (third and fourth) metacarpal bones, in which the fusion extended along the entire length of the bone except at the distal end, diverged to form separate articulations with cross-ponding digits. As described in all ruminant species, especially the camel, there were two digits, and each digit consisted of three phalanges and two proximal sesamoid bones. Our radiographic x-ray data revealed that the complete radiopaque septum that completely divided the medullary cavity into two separate parts was clear from the dorsopalmar view, while the lateral view showed the proximal sesamoid bones that were placed over each other and located palmar to the head of the large metacarpal bone. In conclusion, our study reveals the adaptations of the Arabian one-humped camel to Egyptian conditions, aiding in the early diagnosis of lameness and digit problems and enabling veterinarians and camel owners to better address these issues, thereby improving the overall health and well-being of these animals.

Evaluation of treatment processes in childhood fifth metacarpal bone (Boxer) fractures with QuickDASH scoring system.

OBJECTIVE: Metacarpal fractures are one of the most common orthopedic injuries seen in emergency departments. Despite this, only a few data have been published about the epidemiology of metacarpal fractures. Simple radiographs are the standard imaging modality used to diagnose boxer fractures and determine the degree of angulation. Fractures and angulations should be identified by anteroposterior and lateral radiographs. The aim of this study was to follow the healing after closed reduction of fifth metacarpal neck fractures in a pediatric population using the QuickDASH score to determine whether it results in clinically significant improvement. SUBJECTS AND METHODS: Between 2020 and 2022, our clinical record database for all metacarpal fractures treated at our institution was searched retrospectively every month. Children aged 18 years and younger with fifth metacarpal neck fractures treated with closed reduction and immobilization in our tertiary care emergency clinic were retrospectively reviewed. RESULTS: 52 pediatric patients were included in the study. The mean age at the time of injury was 14.04 years (SD=2.10, range=10-18 years). 92.30% (n=48) of the patients were male, and 7.70% (n=4) were female. CONCLUSIONS: Accurate diagnosis and appropriate treatment are crucial in the management of childhood fifth metacarpal fractures to ensure proper healing, prevent long-term complications, and facilitate optimal functional recovery.

Equine skeletal scintigraphy: Comparing lesion detection ability of methylene diphosphonate and hydroxymethylene diphosphonate in the caudal cervical and proximal metacarpal/metatarsal regions.

BACKGROUND: Data regarding the lesion detection ability of different radiotracers are lacking in equine bone scintigraphy. METHODS: In this prospective study, hydroxymethylene diphosphonate (HMDP) and methylene diphosphonate (MDP) were compared in horses with increased radiopharmaceutical uptake either in the caudal cervical region (CS group) or in the proximal metacarpal/metatarsal region (PMR group). Region of interest analysis was used to determine normal bone-to-soft tissue ratios, lesion-to-normal bone ratios and lesion-to-soft tissue ratios. Qualitative scoring and total count rates were recorded for each image. RESULTS: A total of 213 scintigrams were included. Within the PMR group, there were significantly higher lesion-to-normal bone ratios for MDP compared with HMDP (p = 0.02). In the CS group, normal bone-to-soft tissue ratios were significantly higher for HMDP (p = 0.01). The interobserver agreement with regard to the qualitative assessment of the scintigrams was poor. LIMITATION: Paired studies, comparing the different radiotracers in the same patient, were not feasible. CONCLUSION: This study revealed minor differences between the two radiotracers, although these have no practical implications. Both radiopharmaceuticals are well suited for detecting lesions at the investigated sites using equine bone scintigraphy.

Influence of microarchitecture on stressed volume and mechanical fatigue behaviour of equine subchondral bone.

Fractures of the equine metacarpophalangeal (MCP) joint are among the most common and fatal injuries experienced by racehorses. These bone injuries are a direct result of repetitive, high intensity loading of the skeleton during racing and training and there is consensus that they represent a mechanical fatigue phenomenon. Existing work has found the fatigue life of bone to be strongly determined by bone microarchitecture and the resulting stressed volume (i.e., the volume of bone stressed above assumed yield). The purpose of this study was to quantify the influence of bone microarchitecture on the mechanical fatigue behaviour of equine subchondral bone from the MCP joint across a wide variety of sample types. Forty-eight subchondral bone samples were prepared from the third metacarpal (MC3) and proximal phalanx (P1) of 8 horses and subsequently imaged using high resolution micro-computed tomography (µCT) to quantify microarchitectural features of interest, including bone volume fraction, tissue mineral density, pore size, pore spacing, and pore number. Samples were cyclically loaded in compression to a stress of 70 MPa, and fatigue life was defined as the number of cycles until failure. Finite element models were created from the µCT images and used to quantify stressed volume. Based on the expected log point-wise predictive density, stressed volume was a strong predictor of fatigue life in both the MC3 and P1. A regional analysis indicated fatigue life was more strongly associated with bone volume fraction in the superficial (r2 = 0.32, p < 0.001) and middle (r2 = 0.70, p < 0.001) regions of the subchondral bone, indicating the prominent role that the cortical plate played in the fatigue resistance of equine subchondral bone. By improving our understanding of the variance in fatigue life measurements, this research helps clarify the underlying mechanisms of the mechanical fatigue process and provides a basic understanding of subchondral bone injuries in the equine fetlock joint.

Novel Mini-Invasive Surgical Technique for Treating Fifth Metacarpal Neck Fractures: A Case Report.

BACKGROUND Fracture of the fifth metacarpal of the hand is due to trauma to the clenched fist. The non-displaced fracture can be treated by splinting and immobilization, but fracture dislocation requires individualized management to ensure the return of function. The Jahss maneuver for reduction of volar displaced metacarpal neck fractures involves flexion of the metacarpophalangeal and proximal interphalangeal joint at 90°, with the proximal phalanx used to reduce the metacarpal head. This report is of a 25-year-old male Italian pianist with a displaced fifth metacarpal neck fracture successfully treated by reduction using the Jahss maneuver and K-wire attachment of subchondral bone to the metacarpal. CASE REPORT A pianist presented with a trauma to his right hand due to punching a wall. Radiograph images demonstrated an angulated, displaced right fifth neck fracture. A specific approach was decided, considering the complexity of the musical movements and the patient's performance needs. After fracture's reduction by the Jahss maneuver, 2 retrograde cross-pinning K-wires were inserted at the subchondral bone of the metacarpal head. Healing under splinting was uneventful, and the K-wires were removed after 45 days. At 4 months after surgery, the patient had complete recovery of both range of motion and strength. CONCLUSIONS Our technique avoided piercing the metacarpophalangeal joint capsule, preventing extensor tendon damage, dislocation, instability, and pain and retraction of the extensor cuff. This novel mini-invasive technique successfully achieved early metacarpophalangeal joint motion, joint stability, and complete recovery of movements in all planes.

Basal osteotomy of the first metacarpal using patient-specific guides and instrumentation: biomechanical and 3D CT-based analysis.

INTRODUCTION: The aim of this study was to investigate the radiological outcomes of proximal closing metacarpal extension osteotomies using patient-specific guides and instruments (PSI) in early-stage trapeziometacarpal osteoarthritis to gain further insight into the joint loading surface and the benefits of the procedure. METHODS: In a prospective observational study, nine patients were included between 11/2020 and 12/2021, undergoing a total of ten proximal metacarpal extension osteotomies for basal thumb osteoarthritis. Computer-assisted surgical planning was performed using computed tomography (CT) and three-dimensional (3D) segmentation, allowing the fabrication of 3D-printed PSIs for surgical treatment. Inclusion criteria were a 1-year follow-up by CT to assess postoperative correction of the positional shift of the first metacarpal (MC1) and the location of peak loads compared with the preoperative situation. RESULTS: Radiographic analysis of the peak loading zone revealed a mean displacement on the articular surface of the trapezius of 0.4 mm ± 1.4 mm to radial and 0.1 mm ± 1.2 mm to palmar, and on the articular surface of the MC1 of 0.4 mm ± 1.4 mm to radial and 0.1 mm ± 1.2 mm to dorsal. CONCLUSION: There were trends indicating that a flatter pressure distribution and a dorsal shift of the peak loading zone may contribute to an improvement in subjective pain and patient satisfaction associated with this surgical procedure. The non-significant radiological results and the minor dorsal-radial shifts in our small study group limit a firm conclusion. LEVEL OF EVIDENCE: III.

Positron emission tomography assessment of metacarpal/metatarsal condylar fractures post surgical repair: Prospective study in 14 racehorses.

OBJECTIVES: To assess 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) findings associated with metacarpal/metatarsal condylar fractures at the time of fracture repair and through healing. STUDY DESIGN: Prospective descriptive study. ANIMALS: Fourteen Thoroughbred racehorses. METHODS: 18F-NaF PET was performed within 4 days of surgical metacarpal/metatarsal condylar fracture repair, on both the injured and contralateral limb. Follow-up PET scans were offered at 3- and 5-months post fracture repair. Areas of abnormal uptake were assessed using a previously validated grading system. RESULTS: Eight fractures were located in the parasagittal groove (PSG) (six lateral and two medial) and six fractures were located abaxial to the PSG (non-PSG) through the palmar/plantar condyle (all lateral). All horses in the latter group had uptake in the lateral palmar condyle of the contralateral limb suggestive of stress remodeling. Three horses with PSG fractures had uptake in a similar location in the contralateral limb. Horses with lateral condylar fracture only presented minimal or mild uptake in the medial condyle, which is considered atypical in the front limbs for horses in full training. Four horses developed periarticular uptake in the postoperative period suggestive of degenerative joint disease, three of these horses had persistent uptake at the fracture site. These four horses did not return to racing successfully. CONCLUSION: The findings of this study provide evidence of pre-existing lesions and specific uptake patterns in racehorses suffering from metacarpal/metatarsal condylar fractures. CLINICAL SIGNIFICANCE: PET has a possible role in the prevention, diagnosis, and postoperative monitoring of metacarpal/metatarsal condylar fractures in racehorses.