Introduction: The metacarpophalangeal joint of the thumb is prone to frequent injury in the capsule and collateral ligaments, especially the ulnar collateral ligament. Delayed diagnosis, inappropriate treatment or progressive laxity of the ligament complex can lead to chronic instability of the MCP joint of the thumb. Various surgical repair procedures have been described. We present the surgical procedure consisting of a bone-retinaculum-bone autograft taken from the second tunnel of the flexor retinaculum of the carpus. Purpose: Our purpose is to present the experience of seven cases in which chronic instability of the thumb was treated using a bone-retinaculum-bone autograft. Materials and methods:. Type of study: Descriptive. Period: 2003–2004. Number of cases: 7 (4 women and 3 men) aged 23 to 65. Injury-to-surgery time more than one year. Results:. - We achieved stability of the MCP joint in all cases. - The metacarpophalangeal and interphalangeal joint balance was not diminished. - The grasp force was sustained at over 80% of that of the healthy side. - Two elderly women were not employed; the other five returned to their previous jobs. Conclusions: Given the results obtained, we think this is an excellent method for deferred reconstruction of thumb instability and, although it involves considerable technical difficulty, we feel it is an option to bear in mind for this type of injury

This prospective controlled clinical trial compares the outcomes of metacarpophalangeal (MCP) arthroplasty in rheumatoid arthritis patients using the Swanson (S) and NeuFlex (N) MCP implants. Forty hands (thirty-seven patients) were randomised and evaluated preoperatively and at one year following MCP arthroplasty in digits two to five for range of motion (ROM; active and passive extension and flexion), ulnar drift and grip strength. Both implants restored extension and corrected flexion deformities. There was no significant difference in extension of all digits (summed) between the NeuFlex and Swanson implants (N: −20.8°; S: −13.8°; p=0.29). The NeuFlex implant, which is pre-flexed at 30°, preserved more flexion at the MCP joint than the Swanson implant in all digits (summed) (N:74.5°; S:55.8°; p=0.005), with the greatest difference observed in the fifth digit (N:69.6°; S:48.7°; p=0.009). The total arc of motion improved in all digits, with no significant differences between the Neu-Flex and Swanson groups in the second through fourth digits (N:53.8°; S:43.8°; p=0.154); a significantly greater improvement was observed in the NeuFlex group for the fifth digit (N:53.3°; S:42.5°; p=0.028). Both implants corrected ulnar drift deformity, while neither led to loss of grip strength. Hand function as measured by Sollerman score and Michigan Hand Questionnaire (MHQ) improved significantly in both groups (p=0.0119, p< 0.0001, respectively) with no significant difference between the Swanson and NeuFlex implants, except for MHQ function, aesthetics, and overall scores, which demonstrated superiority of the Swanson. Overall, there was a significant improvement in the range of motion, deformity and grip strength following MCP arthroplasty for the full patient group. While both implants restored similar amounts of extension, the NeuFlex implant maintained greater flexion and total range of motion, with the greatest difference in the fifth digit. The Swanson implant had better MHQ function and aesthetics subscores

Ulnar drift is a common deformity in the hands of patients with rheumatoid arthritis. There is little in the literature regarding the value of crossed intrinsic transfer with MCPJ arthroplasty (Hellum 1968, Stothard et al 1991). In addition the significance of recurrent ulnar drift on hand function is unknown. The aim of this study is to assess if the addition of crossed intrinsic transfer to metacarpophalangeal arthroplasty has an effect on the recurrence of ulnar drift and to overall hand function. This is a retrospective comparative study. 73 hands in patients with rheumatoid arthritis undergoing primary 2nd to 5th metacarpophalangeal joint (MCPJ) replacements were studied. In 28 hands a crossed intrinsic transfer was performed and in 45 hands it was not . A similar splintage and rehabilitation programme was followed in each group. Mean follow up was 50 months. Ulnar drift and active range range of motion, Sequential Occupational Dexterity Assessment (SODA) functional score, patient satisfaction , grip strength. The two groups had similar preoperative ulnar drift (crossed intrinsic transfer group mean 27 degrees, comparative group 29 degrees, p=0.44). At follow up the crossed intrinsic transfer group had statistically less ulnar drift (crossed intrinsic transfer group mean 6 degrees, comparative group 14 degrees, p=0.01). There was no difference at follow up in active flexion, extensor lag, SODA score, grip strength and patient satisfaction (both groups had 70% improved function)

Fractures about the radial or ulnar aspects of the base of the proximal phalanx or the metacarpal head represent collateral ligament avulsion injuries. Unlike such injuries in the metacarpophalangeal joint of the thumb these injuries are rare and have received scant attention in the literature.

The results of open reduction and internal fixation, highlighting the surgical approach and technique, of collateral ligament avulsion fractures about the metacar-pophalangeal joints of the fingers are presented.

Over a five year period sixteen patients presented to the hand injury service with the above injury. Thirteen of these fractures occurred at the base of the proximal phalanx. Fourteen were acute injuries and two non-unions. These fractures affected a predominantly young population (average age 24 years) and the majority were sustained during sporting activities. All were treated by ORIF except for one in which the patient declined operative treatment. Metacarpal head fractures are assessed through a standard dorsal approach but as the collateral ligament inserts into the volar - lateral aspect of the proximal phalangeal base access to this fracture is best achieved via a volar approach to the digit. Fractures were stabilized with a single interfragmentary screw.

Surgical fixation gave satisfactory results in fourteen cases. All these patients had a full range of finger movement within 3 weeks. One patient developed symptoms suggestive of RSD. At 3 months review all fractures treated by ORIF had united. The patient who declined surgical treatment developed a symptomatic non-union.

Conservative treatment of these unstable fractures leads to non-union. The surgical anatomy dictates the surgical approach, with fractures at the proximal phalangeal base best accessed via a volar approach. ORIF restores joint surface congruity, establishes union and provides stable fixation to allow early mobilisation and return to normal activities.

Introduction Finger prostheses lack the long-term clinical success associated with hip and knee replacements. The most commonly implanted type of finger prostheses consists of single-piece silicone designs such as the Swanson, the Sutter and the NeuFlex [1]. Such designs act as flexible spacers around which a process of encapsulation can occur. A recent long-term study stated that, at an average of 14 years after surgery, Swanson meta-carpophalangeal (MCP) prostheses showed a fracture rate of 67% compared with 52% for Sutter MCP prostheses [2]. A 2005 paper reported that, at 2 years follow-up, the fracture rates were 13% and 20% respectively for these two designs [3]. Perhaps such high rates could be reduced if a better understanding of the nature of fracture of these implants was attained.

Materials and Methods Twelve Sutter MCP prostheses were obtained from three hands (two dominant) of two women and one man who were aged 56–66 years at time of surgery [4]. They were retrieved at a mean of 42 (range 32–53) months following implantation. All patients had rheumatoid arthritis. Of the twelve explanted prostheses, eleven had fractured, ten completely. These fractured prostheses were visually examined and were then sliced so that, after washing and gold-coating, the two fracture faces of each prosthesis could be examined using a Hitachi S-4700 scanning electron microscope (SEM).

Results and Discussion All of the ten total fractures occurred at the junction of the distal stem and the hinge of the implant. Visual inspection showed that the initial point of fracture was on the dorsal aspect of the prosthesis, indicating that fracture is due to the subluxing forces seen in rheumatoid MCP joints. Also, the fracture began distally and travelled in a slightly proximal direction as well as in the dominant dorsal to palmar direction. For the prostheses removed from a right hand, it appeared that the crack direction was also from ulnar to radial. When all of the fracture faces were examined by SEM, significant variation was seen. Some fracture faces appeared to show surface gouging of the material, which may have been caused by bone after fracture had taken place, therefore indicating that fracture had occurred long before the prostheses were removed. In contrast another fracture face showed what appeared to be a region of gradual abrasion, perhaps caused by osteophytes, next to a relatively smooth zone which could have indicated an area of rapid fracture or tearing. The author is not aware of any similar topographical analysis having been undertaken elsewhere on fractured, ex-vivo silicone MCP prostheses. While the time span between fracture and removal of the implant can never be known precisely, so that the ‘virgin’ fracture face could have been damaged post-fracture, it is still hoped that such ex-vivo analysis can contribute to improved finger prostheses.

Aims

Complete ruptures of the ulnar collateral ligament (UCL) of the thumb are a common injury, yet little is known about their current management in the UK. The objective of this study was to assess the way complete UCL ruptures are managed in the UK.

Aims: The aim of the present study was to compare the functional outcome between silastic Swanson and Sutter implants in metacarpophalangeal joints in a prospective and randomised of study of patients with rheumatoid arthritis. Methods: The study was prospective and randomised. Thematerial comprised 53 patients (6 men, 47 women) and 58 hands; a total of 89 Swanson and 126 Sutter implants were installed. The mean follow-up time was 57 (40–80) and 55 (36–79) months, respectively. Results: Active extension was corrected similarly in both groups. In the Swanson group from median [inter-quartile rate (IQR)] 22° (8, 44) to 12° (0,20), and in the Sutter group from 19° (7, 37) to 16 (5, 25). The median active flexion decreased less in the Sutter group from 75° (69, 84) to 64° (53, 72) vs. Swanson from 83° (77, 90) to 58° (48, 64) during the follow-up, and with that respect the difference between the groups was statistically significant (p=0.01). Statistically significant difference (p=0.03) was detected in correction of ulnar deviation only in ring finger: in the Swanson group from median 25°(6°, 34°) ulnar deviation to 1°(2°radial, 9°) radial deviation and in the Sutter group from 14°(7°, 28°) to 5°(0°, 13∞) respectively. Conclusion: It appears that the Sutter implant yields at least as good functional results in the MCP replacement as the Swanson prosthesis.

We randomised 79 patients (84 hands, 90 fingers) with Dupuytren’s contracture of the proximal interphalangeal joint to have either a ‘firebreak’ skin graft (39 patients, 41 hands, 44 fingers) or a fasciectomy (40 patients, 43 hands, 46 fingers) if, after full correction, the skin over the proximal phalanx could be easily closed by a Z-plasty. Patients were reviewed after three, six, 12, 24 and 36 months to note any complications, the range of movement and recurrence. Both groups were similar in regard to age, gender and factors considered to influence the outcome such as bilateral disease, family history, the presence of diabetes, smoking and alcohol intake. The degree of contracture of the metacarpophalangeal and interphalangeal joints of the operated fingers was similar in the two groups and both were comparable in terms of grip strength, range of movement and disability at each follow-up. The recurrence rate was 12.2%. We did not identify any improvement in correction or recurrence of contracture after firebreak dermofasciectomy up to three years after surgery

Aims. In the UK, fasciectomy for Dupuytren’s contracture is generally performed under general or regional anaesthetic, with an arm tourniquet and in a hospital setting. We have changed our practice to use local anaesthetic with adrenaline, no arm tourniquet, and perform the surgery in a community setting. We present the outcome of a consecutive series of 30 patients. Methods. Prospective data were collected for 30 patients undergoing open fasciectomy on 36 digits (six having two digits affected), over a one-year period and under the care of two surgeons. In total, 10 ml to 20 ml volume of 1% lidocaine with 1:100,000 adrenaline was used. A standard postoperative rehabilitation regime was used. Preoperative health scores, goniometer measurements of metacarpophalangeal (MCP), proximal interphalangeal (PIP) contractures, and Unité Rheumatologique des Affections de la Main (URAM) scores were measured pre- and postoperatively at six and 12 weeks. Results. The mean preoperative contractures were 35.3° (0° to 90°) at the metacarpophalangeal joint (MCPJ), 32.5° (0° to 90°) at proximal interphalangeal joint (PIPJ) (a combined deformity of 67.8°). The mean correction was 33.6° (0° to 90°) for the MCPJ and 18.2° (0° to 70°) for the PIPJ leading to a combined correction of 51.8°. There was a complete deformity correction in 21 fingers (59.5%) and partial correction in 14 digits (37.8%) with no correction in one finger. The mean residual deformities for the partial/uncorrected group were MCP 4.2° (0° to 30°), and PIP 26.1° (0° to 85°). For those achieving a full correction the mean preoperative contracture was less particularly at the PIP joint (15.45° (0° to 60°) vs 55.33° (0° to 90°)). Mean preoperative URAM scores were higher in the fully corrected group (17.4 (4 to 31) vs 14.0 (0 to 28)), but lower at three months post-surgery (0.5 (0 to 3) vs 4.40 (0 to 18)), with both groups showing improvements. Infections occurred in two patients (three digits) and both were successfully treated with oral antibiotics. No other complications were noted. The estimated cost of a fasciectomy under local anaesthetic in the community was £184.82 per patient. The estimated hospital theatre costs for a fasciectomy was £1,146.62 under general anaesthetic (GA), and £1,085.30 under an axillary block. Conclusion. This study suggests that a fasciectomy performed under local anaesthetic with adrenaline and without an arm tourniquet and in a community setting is safe, and results in favourable outcomes regarding the degree of correction of contracture achieved, functional scores, and short-term complications. Local anaesthetic fasciectomy in a community setting achieves a saving of £961.80 for a GA and £900.48 for an axillary block per case. Cite this article: Bone Joint J 2020;102-B(10):1354–1358

Introduction: The thumb metacarpophalangeal (MCP) joint dislocations in children are relatively uncommon and scarcely described in the English literature. The aim of this study was to report the clinical course and outcome of traumatic dislocations of the thumb metacarpophalangeal joints in children. Materials and methods: We retrospectively reviewed a cohort of 37 traumatic dislocations of the thumb metacarpophalangeal joints in 37 children between 1990 and 2005. All patients were treated by five orthopaedic surgeons at a tertiary referral children’s hospital. The outcome measures included patient demographics, method of reduction and short-term outcome. The mean follow-up was 6 weeks. Results: The mean age at injury was 7.3 years. These occurred predominantly in boys (78.3%) and were dorsal dislocations in 97.2%. Thirty-three presented acutely on the day of injury, while 3 within 1–2 weeks. Four patients needed open reduction with or without temporary stabilisation. Thirty-three had a closed reduction (under general anaesthesia-12, under ring block-5, under sedation-9 and without anaesthesia-7). All patients undergoing closed or open reduction under anaesthesia had 1–4 unsuccessful relocation attempts. Two of four open reductions revealed soft tissue interposition of volar plate and flexor pollicis longus. Post-reduction, the thumb was immobilised in a thumb spica or plaster for 2 to 3 weeks period. All gained good result. There were no infections, recurrent dislocation or gross stiffness. Conclusion: Thumb metacarpophalangeal (MCP) joint dislocations in children are mostly dorsal and managed non-operatively in majority with satisfactory outcome. Irreducible dislocations may need open reduction due to volar plate and flexor pollicis longus tendon interposition

The rheological properties of synovial fluid (SF) are largely attributed to the presence of high molecular weight hyaluronic acid (HA). In normal SF, HA has been shown to be an anti-inflammatory molecule able to increase the viscosity and promote endogenous production of HA. The aim of the present report was to investigate the possible effect of HA concentration in rheological properties (elastic modulus, G´ and viscous modulus, G´´) of osteoarthritic equine SF. For this purpose, SF from intercarpal, metacarpophalangeal and distal interphalangeal joint was aspirated by aseptic arthrocentesis from 60 Warmblood horses. For determining HA concentrations in equine SF samples, a commercially available ELISA kit was used. Additionally, full rheological sample characterization was carried out with an AR-G2 rheometer (TA Instruments Ltd., UK) in order to measure the elastic G´ and viscous G´´ moduli, at horse's body (37.5 ºC) temperature. The ANOVA findings revealed statistically significant main effects of the factors Joint Type (p = 0.001), and main effects of covariates Age (p = 0.019) and HA (p < 0.001) on the mean values of logG” and logG' measurements. Interpreting the coefficients of the covariate HA, a positive correlation of HA was detected on the response logG” and logG' measurements. Collectively, these data illustrate the role of HA in equine pathological SF

Objective. We explanted NeuFlex metacarpophalangeal (MP) joint prostheses to identify common features, such as position of fracture, and thus better understand the reasons for implant failure. Methods. Explanted NeuFlex MP joint prostheses were retrieved as part of an-ongoing implant retrieval programme. Following revision MP joint surgery the implants were cleaned and sent for assessment. Ethical advice was sought but not required. The explants were photographed. The position of fracture, if any, was noted. Patient demographics were recorded. Results. Thirty NeuFlex MP explants were available. Seven (23%) were not fractured. Eleven explants (37%) had fractured at the hinge; nine (30%) had fractured at the junction of the distal stem and hinge; and three (10%) had fractured at both the hinge and distal stem. NeuFlex MP joint explants ranged in size from 0 to 40. Smaller sizes were retrieved from smaller fingers; larger implants came from the middle and index fingers. The age at revision ranged from 43 to 81 (median 58) years. Time in vivo ranged from 6 to 120 (median 58.5) months. All but two implants were obtained from rheumatoid joints, the remainder had osteoarthritis. Discolouration of some explants had occurred; other explants appeared to show no colour change. Conclusions. This is the first report of the position of fracture of NeuFlex explants. It is also the largest report of silicone arthroplasty explants. The majority (77%) had fractured. Nine (30%) NeuFlex explants had fractured at the junction of the distal stem and hinge; the typical position seen with Swanson and Sutter/Avanta MP joint explants. Eleven (37%) fractured across the hinge; this has not previously been reported although has been seen in in vitro testing. The hinge is thinner than the hinge-stem junction so may be at risk of more rapid failure, however the median time in vivo for hinge fractures was 63 months as opposed to 54 months for fractures at the distal stem. Intriguingly, 3 (10%) NeuFlex explants suffered fractures both at the hinge and at the junction of the distal stem and hinge which has also never been reported previously. Fracture at the junction of the distal stem and hinge shows the importance of subluxing forces in rheumatoid MP joints and therefore suggests these need to be mitigated as much as possible. Fracture across the hinge could indicate this as a position which could be increased in thickness, to increase the time taken to fracture, although there may be a concomitant increase in stiffness of the implant. With improved designs, patients might suffer fewer or later failures. The latest Norwegian Arthroplasty Registry report shows that revision MP joint arthroplasties accounted for 42% of all MP joint replacement operations in 2015. Therefore, this is an important area where opportunities exist to reduce revision rates

Study. This is a prospective double blind, placebo controlled trial. Collagenase Clostridium Histolyticum was effective and well tolerated used in well palpable cords of Dupuytren's Contracture. Concurrent fingers treatment with early complications have been reported. Patients reported outcome measures have been obtained. Materials & Method. 143 fingers were treated in 125 patients. Deformity of more than 30° at metacarpo phalangeal joints and more than 20° at proximal interphalangeal joints with well palpable cord were selected in this study. Finger straightening procedure was undertaken at 24–72 hours post injection. Prospectively evaluated for early complications, extent of correction, residual deformity and recurrence rate at 3 years and 6 months follow up. Concurrent fingers were treated without serious side effects. Results. Full correction was achieved in 130 fingers (91%). Residual flexion deformity noted in mainly in PIPJ with flexion 80° or more. At four years follow up, the recurrence rate was noted in Metacarpophalangeal Joints in 4(3%)fingers and Proximal Inter Phalangeal Joints in 12(9%) fingers. Patient reported outcome measures have been collected and expressed high degree of satisfaction. Conclusion. Most local complications resolved within two weeks of the injection. Isolated MPJ deformity is more likely to be corrected fully. Isolated Proximal Interphalangeal Joints and combined Proximal Interphalangeal Joints and Metacarpo Phalangeal Joints contractures are mostly end up in residual flexion. Concurrent finger treatment was uneventful

Aims

The paediatric trigger thumb is a distinct clinical entity with unique anatomical abnormalities. The aim of this study was to present the long-term outcomes of A1 pulley release in idiopathic paediatric trigger thumbs based on established patient-reported outcome measures.

Ten cases of complete rupture of the collateral ligaments of the metacarpophalangeal finger joints are reported. The nature of this injury, the pre-operative morbidity and the intra-operative pathology are analysed. In all cases surgery was performed with satisfactory results. Operation is indicated for joint stability, grip and pinch strength, pain control and early functional recovery

Aim. To describe the epidemiology, clinical features and outcomes of native joint septic arthritis in adults admitted to Middlemore Hospital in Auckland, New Zealand. Method. Single-centre retrospective cohort study from 2009 to 2014. Patients ≥16 years of age were identified using ICD-10AM coding data. Electronic records were reviewed for demographic, clinical, laboratory, treatment and outcome data. Total and hemi-arthroplasty infections were excluded. Results. 543 episodes in 521 patients were included, with 90% fulfilling Modified Newman's criteria. Septic arthritis incidence was 26/100,000 patient years and was unchanged over the study period. Incidence correlated strongly with age (R. 2. =0.79) and socioeconomic deprivation (R. 2. =0.76). Median age was 49 years, and gender 70% male. Ethnicity was Pacific Island in 36% (22.8% of catchment population). The most commonly involved joints were hand interphalangeal (19%), knee (19%), metacarpophalangeal (17%) and glenohumeral (11%). Arthritis was monoarticular in 93%. Underlying conditions included current smoking (42%), osteoarthritis (29%), diabetes (22%) and gout (15%). Rheumatoid and seronegative arthritis were uncommon (each 2%). Skin/soft tissue infection occurred within 3 months prior in 38%. Osteomyelitis occurred in 26%. Sources of infection included haematogenous (42%), traumatic (34%), and iatrogenic (17%). Causative organism(s) were isolated in 80% of episodes, most commonly Staphylococcus aureus (53%, 13% of which were MRSA) then Streptococcus pyogenes (15%). 28% of culture-positive episodes were polymicrobial. Median antibiotic duration was 4 weeks, with 38% having definitive therapy orally. A median of 1 surgical procedure was undertaken during treatment. Mortality at 30 days was 3%, at 90 days 5% and treatment failure (defined as any of: death <90 days; relapse; reinfection; or ongoing joint infection leading to readmission, amputation, arthrodesis or excision arthroplasty) occurred in 17%. Treatment failure was significantly more common in cases involving large joints (23%, (69/302) vs. 11%, (26/241), p=0.0002) and in haematogenous episodes versus traumatic episodes (21% (47/229) vs. 10% (19/168), p=0.0045). Conclusions. This is the largest series of adult native joint septic arthritis currently available. The extremely high observed septic arthritis incidence (26/100,000 person years) may relate to high rates of skin and soft tissue infection in Auckland, particularly among Pacific people. Small joint infection, often excluded from previous studies, is associated with significantly better outcomes than large-joint infection. Mortality is lower in this cohort than previously reported, possibly due to the inclusion of small joint infections and exclusion of prosthetic joint infections. Acknowledgements. No additional funding was received for this work

This annotation reviews current concepts on the three most common surgical approaches used for proximal interphalangeal joint arthroplasty: dorsal, volar, and lateral. Advantages and disadvantages of each are highlighted, and the outcomes are discussed.

Cite this article: Bone Joint J 2022;104-B(12):1329–1333.

The April 2023 Wrist & Hand Roundup³⁶⁰ looks at: MRI-based classification for acute scaphoid injuries: the OxSMART; Deep learning for detection of scaphoid fractures?; Ulnar shortening osteotomy in adolescents; Cost-utility analysis of thumb carpometacarpal resection arthroplasty; Arthritis of the wrist following scaphoid fracture nonunion; Extensor hood injuries in elite boxers; Risk factors for reoperation after flexor tendon repair; Nonoperative versus operative treatment for displaced finger metacarpal shaft fractures.

Background: In 80% of patients with rheumatoid arthritis the metacarpophalangeal (MP) joints are involved with increasing destruction and loss of function. Silicone arhtroplasties of the MP joints produce a limited range of motion, increasing osteolysis and fractures of the implants. The cementless, unconstrained design of the ElogenicsTM prosthesis is a new concept for treating the MP joints of rheumatoid patients. Methods: In a prospective study 72 ElogenicsTM prosthesis were implanted, 62 in patients with rheumatoid arthritis, osteoarthritis (n=4), polyarthritis (n=5) and 1 after revision of a silicone implant. The patients were reexamined after an average follow up of 21 months (12–51 months) clinically and radiologically. Results: The average active range of motion for extension to flexion increased from 0/18/65° before surgery to 0/14/71° after surgery. The remaining ulnar drift was 12° (preoperative 18°!). Pain in the visual analogue scale improved from 2.3 to 1.7 postoperatively. Eight palmar luxations of the implants were recognized. They were revised and are stable during the follow-up. No infection occurred. Two prostheses were changed because of loosening. The X-rays showed osteointegration in the metacarpal components. Radiolucent zones were found in progress at the basis on the palangeal components. Conclusion: The short- and midterm results after implantation of the cementless, unconstrained ElogenicsTM prosthesis show an improved hand function and pain relief. The design of the implant may solve the accepted postoperative problem of instability of the MP joints

Objective: To challenge the validity of using biomarker concentrations in synovial fluid for the assessment of joint pathology. Hypothesis: Synovial fluid biomarker concentrations are influenced by both cartilage and synovial fluid volumes. Methods: Synovial fluid volumes were determined from the equine metacarpophalangeal (MCP), proximal inter-phalangeal (PIP) and distal interphalangeal (DIP) joints, which have different disease prevalences. Chondrocyte density was calculated from a defined site in each joint. Cartilage volume was measured by novel application of Peripheral Quantitative Computed Tomography (pQCT). Cartilage oligomeric matrix protein (COMP), glycos-aminoglycans (GAG) and total protein (TP) concentrations were measured and then adjusted for cartilage and synovial fluid volume and compared between joints. Results: Mean synovial fluid volume was significantly greater in the MCP than the distal joints (p< 0.0001) (3.2 ±0.5ml, 0.5 ±0.1ml and 0.6 ±0.1ml respectively). In contrast, the DIP had the greatest cartilage volume compared to the proximal joints (5360 ±667mm3 2640mm3, 1940 ±331mm3 respectively). There was no significant difference in the cartilage cellularity between all joints. The DIP had higher TP, COMP and GAG concentrations, however, when values were expressed per unit cartilage volume the opposite was found, with the MCP then exhibiting significantly higher concentrations. Conclusions: These data show the joint with the highest prevalence to osteoarthritis has the lowest biomarker synovial fluid concentrations but the highest biomarker levels per unit cartilage, suggesting a higher release. These results indicate that meaningful interpretation of biomarkers in synovial fluid require consideration of both fluid and cartilage volume