Effect of induced unilateral synovitis of distal intertarsal and tarsometatarsal joints on sagittal plane kinematics and kinetics of trotting horses

OBJECTIVE: To study the effect of unilateral synovitis in the distal intertarsal and tarsometatarsal joints on locomotion, including the compensating effects within and between limbs. ANIMALS: 4 clinically normal horses. PROCEDURE: Gait analyses including kinematics, force plate, and inverse dynamic analysis were performed at the trot before lameness, after which synovitis was induced by injecting endotoxin into the right distal intertarsal and tarsometatarsal joints. Gait analyses were repeated 24 to 30 hours later during lameness. Differences between the stride variables during the 2 conditions (lame and sound) were identified. RESULTS: Tarsal joint range of motion, peak vertical force, and vertical impulse were decreased during lameness. Mechanical deficits included a decrease in negative work performed by the tarsal extensors during the early stance phase and a decrease in positive work by the tarsal extensors during push off. No compensatory changes in work were performed by other joints within the lame hind limb during the stance phase. Vertical impulse in the diagonal forelimb decreased, but there were no significant changes in forces or impulses in the ipsilateral forelimb or contralateral hind limb. CONCLUSION AND CLINICAL RELEVANCE: Results indicate that horses are able to manage mild, unilateral hind limb lameness by reducing the airborne phase of the stride rather than by increased loading of the compensating limbs.     

Surgical arthrodesis of distal tarsal joints in 17 horses clinically affected with osteoarthritis

Objective To evaluate the outcome of 17 horses that underwent surgical arthrodesis of the tarsometatarsal and distal intertarsal joints for treatment of lameness due to osteoarthritis.
Design Retrospective clinical study using client-owned animals.
Procedure Horses with hindlimb lameness were diagnosed with osteoarthritis of the distal tarsal joints following relief of lameness after intra-articular anaesthesia or intra-articular corticosteroid injection. Surgery to stimulate ankylosis was performed on 27 hocks by placing 3 diverging 3.2 mm drill holes approximately 3 cm through the tarsometatarsal and distal intertarsal joints from the medial aspect of the limb. The results of surgery were assessed by postoperative examinations, telephone communication with clients and analysis of race results.
Results In 71% of horses, surgery was considered to be successful as determined by clinical examination or telephone communication with clients: six of these horses had unilateral surgery and six had bilateral surgery. This represented 85% (6/7) of horses undergoing unilateral surgery and 60% (6/10) of horses having bilateral surgery. All (8/8) racing Standardbreds and 67% (4/6) of racing Thoroughbreds were considered a success. The average time between surgery and a return to racing was 9.5 months.
Conclusions The surgical technique used here can provide resolution of lameness from osteoarthritis of distal tarsal joints with a success rate similar to other reported surgical arthrodesis techniques that are more invasive and have a greater morbidity.     

Use of intra-articular administration of ethyl alcohol for arthrodesis of the tarsometatarsal joint in healthy horses

OBJECTIVE: To evaluate the efficacy and safety of intra-articular administration of ethyl alcohol for arthrodesis of tarsometatarsal joints in horses. ANIMALS: 8 healthy female horses without lameness or radiographic evidence of tarsal joint osteoarthritis. PROCEDURE: In each horse, 1 tarsometatarsal joint was treated with 4 mL of 70% ethyl alcohol and the opposite joint was treated with 4 mL of 95% ethyl alcohol. Lameness examinations were performed daily for 2 weeks, followed by monthly evaluations for the duration of the 12-month study. Radiographic evaluations of both tarsi were performed 1 month after injection and every 3 months thereafter. Gross and histologic examinations of the tarsi were undertaken at completion of the study. RESULTS: Horses had minimal to no lameness associated with the treatments. Radiography revealed that 8 of 16 joints were fused by 4 months after treatment, with significantly more joints fused in the 70% ethyl alcohol group. Fifteen of 16 joints were considered fused at postmortem examination at 12 months. Gross and histologic examinations revealed foci of dense mature osteonal bone spanning the joint spaces. Bony fusion appeared to be concentrated on the dorsolateral, centrolateral, and plantarolateral aspects of the joints. Significant differences were not detected between treatment groups for lameness or pathologic findings. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of ethyl alcohol into the tarsometatarsal joint of healthy horses appeared to facilitate arthrodesis of the joint in a pain-free manner. Results warrant further investigation into the potential use of ethyl alcohol in horses clinically affected with osteoarthritis of the tarsometatarsal and distal intertarsal joints.     

The hindlimb in walking horses: 1. Kinematics and ground reaction forces

The objective was to study associations between kinematics and ground reaction forces in the hindlimb of walking horses. Video (60 Hz) and force (2000 Hz) data were gathered for 8 strides from each of 5 sound horses during the walk. Sagittal plane kinematics were measured concurrently with the vertical and longitudinal ground reaction forces. The hindlimb showed rapid loading and braking in the initial 10% stride. The stifle, tarsal and coffin joints flexed and the fetlock joint extended during this period of rapid loading. The vertical ground reaction force showed 2 peaks separated by a dip; this pattern was similar to the fetlock joint angle-time graph. Peaks in the longitudinal ground reaction force did not appear to correspond with kinematic events. Total braking impulse was equal to total propulsive impulse over the entire stride. Flexion and extension of the hip were responsible for protraction and retraction of the entire limb. Maximal protraction occurred shortly before the end of swing and maximal retraction occurred during breakover. During the middle part of stance the tarsal joint extended slowly, while the stifle began to flex when the limb was retracted beyond the midstance position at 28% stride. Flexion cycles of the stifle and tarsal joints were well coordinated during the swing phase to raise the distal limb as it was protracted. The results demonstrate a relationship between limb kinematics and vertical limb loading in the hindlimbs of sound horses. Future studies will elucidate the alterations in response to lameness.     

Chemical arthrodesis of the distal tarsal joints using sodium monoiodoacetate in 104 horses

OBJECTIVE: To evaluate chemical arthrodesis using sodium monoiodoacetate for treatment of degenerative joint disease of the tarsometatarsal and distal intertarsal joints. DESIGN: Retrospective clinical study. METHOD: Horses were diagnosed with degenerative joint disease of one or more of the tarsometatarsal or distal intertarsal joints based on history, lameness examination, radiographic findings and, in some cases, response to intra-articular anaesthesia or medication. Intra-articular injections of sodium monoiodoacetate were performed using 23 gauge needles in the sedated, standing horse. Positive contrast arthrography of the distal intertarsal joint was performed in all horses to evaluate needle placement and the presence or absence of communication with other synovial structures. The mean intra-articular dose of sodium monoiodoacetate was 192 mg. Horses were subject to a graded exercise program commencing 7 to 10 days after treatment. Where possible, follow up lameness examination and radiography was performed at 3, 6, 12 and 24 months after treatment. RESULTS: At 3, 6, 12 and 24 months after treatment, respectively, 0/57, 14/55, 41/50, and 29/34 of horses were sound. At 3, 6, 12 and 24 months after treatment, respectively, 5/55, 24/38, 26/30 and 18/18 of horses had radiographic evidence of ankylosis of treated joints. Post injection pain was marked in 6.7% of horses and significant complications requiring further treatment occurred in 3.8% of horses. CONCLUSIONS: Chemical arthrodesis using sodium monoiodoacetate was an effective treatment method for degenerative joint disease of the distal tarsal joints. The technique was performed in the sedated standing horse and required minimal equipment. Results were comparable to those achieved following surgical arthrodesis. The risk of significant complications was minimised through good technique using an appropriate injection volume and concentration.     

Arthrodesis of the Distal Intertarsal and Tarsometatarsal Joints in the Horse

Arthrodesis created by destruction of the articular surfaces of the distal intertarsal and tarsometatarsal joints by repeated insertion of a drill was studied in one limb of each of nine horses. Postoperatively, the horses were housed in box stalls for 8 weeks and then confined to a paddock for 19 weeks. Clinical and radiographic evaluations were performed prior to surgery, immediately following surgery, and at 2,4, 6, 8,10,12,16, 20, and 27 weeks following surgery. There was a statistically significant positive correlation between decreasing degree of lameness and increasing radiographic evidence of bony fusion; fusion of the distal intertarsal and tarsometatarsal joints was present in five horses 27 weeks after surgery. The horses lost weight during the first 8 weeks after surgery. Flexion of the treated tarsal joints was decreased significantly at the end of the experiment.
Complications encountered included fracture of the third tarsal bone (five horses), instability of the tarsus (four horses), septic arthritis (three horses), and diarrhea (four horses).
Arthrodesis, with this method of surgical drilling of the distal intertarsal and tarsometatarsal joints, is not recommended because of severe pain, prolonged convalescence, and high incidence of complications.     

Use of a three-drill-tract technique for arthrodesis of the distal tarsal joints in horses with distal tarsal osteoarthritis: 54 cases (1990-1999)

OBJECTIVE: To assess the long-term clinical outcome of horses with distal tarsal osteoarthritis (OA) in which a 3-drill-tract technique was used to induce arthrodesis of the affected joints, identify any preoperative or operative factors associated with outcome, and describe any complications associated with the technique. DESIGN: Retrospective study. ANIMALS: 54 horses. PROCEDURE: Medical records were reviewed for information on signalment, use, history, physical and lameness examination findings, surgical technique, and postoperative care. Radiographs were examined, and severity of OA was graded. Follow-up information was obtained through telephone interviews with owners at least 13 months after the procedure. RESULTS: 32 (59%) horses had a successful outcome, 6 (11%) improved but were not sound after surgery, and 16 (30%) did not improve following surgery. Outcome was negatively associated with the previous use of intra-articular injections. Few postoperative complications were evident. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that distal tarsal OA in horses can be successfully treated by means of distal tarsal arthrodesis with a 3-drill-tract technique. Horses with advanced distal tarsal OA are likely to have poorer outcomes, and the procedure will likely be of minimal benefit in horses with concomitant causes of hind limb lameness prior to surgery and in horses with preexisting proximal intertarsal joint disease.     

Surgical arthrodesis for the treatment of osteoarthrosis of the proximal intertarsal, distal intertarsal and tarsometatarsal joints in 30 horses: a comparison of four different techniques

Over a period of seven years, 30 horses were treated by surgical arthrodesis for lameness resulting from osteoarthrosis of the proximal intertarsal, distal intertarsal and tarsometatarsal joints (bone and occult spavin). Twenty-five horses were affected in one hock only and five were affected bilaterally. Four different techniques for achieving arthrodesis were used. Fourteen out of 18 horses (78 per cent) with involvement of the distal intertarsal and tarsometatarsal joints only and six out of 11 horses (55 per cent) in which the proximal intertarsal joint was also involved became sound following surgery. The status of one other horse, with involvement of the proximal intertarsal joint, is not known.     

The origins of acupuncture channel imbalance in pain of the equine hindlimb

Objective: A study was conducted to define the relationship between oriental channel imbalance and pain of the equine hindlimb.Methods: One hundred eighty-five lame and muscle sore horses from a general equine practice in Virginia were examined by a single observer using traditional manual palpation of the acupuncture channels. The six hindlimb channels were evaluated and graded with particular emphasis on the reactivity of three transpositional acupoints, BL 18, BL 19, BL 20, and five traditional veterinary acupoints Yao Zhong, Shen Shu, Xie Qi, Feng Men, and Fu Tu. All lame patients were evaluated with western methods to establish an anatomical diagnosis. All nonlame horses with channel imbalance were treated with either an intra-articular anesthetic, an intra-articular cortisone, methylprednisolone acetate, or a hyaluronate and triamcinalone combination. The medications were injected into either the three compartments of the stifle joint, tarso-metatarsal and distal inter-tarsal joints, metatarsophalangeal joint, or the distal interphalangeal joint The joint injections were conducted in sequence, distal to proximal, until a definitive change in channel imbalance had occurred. Chi Square analysis was used to assess different frequencies of channel imbalance and the sites responsible for that imbalance, with P<0.05.Results: Channel imbalance was only indirectly associated with extra-articular pathology. Intra-articular structures of three joints of the distal hindlimb, the distal tarsus, metatarsophalangeal, and distal interphalangeal, accounted for all the observed abnormal, referred diagnostic acupoints. In the examined population, channel imbalance was significantly more frequently related to the distal tarsus than the hind fetlock, and both of these were significantly more frequently involved than the distal interphalangeal joint. Channel imbalance relating to the dorsal aspect of the digit was significantly more frequent in metatarsophalangeal lameness than in distal tarsal lameness. Neither the stifle nor midback pain was directly associated with projected, as opposed to local, channel imbalance. If projected channel imbalance could be defined as the presence of reactive acupoints not in the immediate vicinity of the local site of pain, then the projected acupoints detected in stifle lameness or back pain were associated with the tarsus or the hind fetlock.Conclusions: The sites of hindlimb pathology resulting in channel imbalance were intra-articular, and they were located within the distal tarsal, the metatarsophalangeal and the distal interphalangeal joints. Channel diagnosis reflected intra-articular inflammation of only these three joints, and further diagnostic procedures were required to establish a definitive western diagnosis. The presence of channel imbalance should be used to determine pattern differentiation in Traditional Chinese Medicine.     

Musculoskeletal problems associated with lameness and poor performance among horses used for barrel racing: 118 cases (2000-2003)

OBJECTIVE: To identify types of musculoskeletal problems associated with lameness or poor performance in horses used for barrel racing. DESIGN: Retrospective case series. ANIMALS: 118 horses. PROCEDURE: Medical records were reviewed for information on signalment, history, physical and lameness examination findings, diagnostic tests performed, diagnosis, and treatment. RESULTS: Most horses were examined because of lameness (n = 72 [61%]) rather than poor performance (46 [39%]), but owner complaint was not significantly associated with age or body weight of the horse. The most common performance change was refusal or failure to turn properly around the first barrel (19/46 [41%]). The right forelimb (n = 57 [48%]) was most commonly affected, followed by the left forelimb (51 [43%]), the left hind limb (31 [26%]), and the right hind limb (25 [21%]). In 31 horses (26%), both forelimbs were affected, and in 6 (5%), both hind limbs were affected. The most common musculoskeletal problems were forelimb foot pain only (n = 39 [33%]), osteoarthritis of the distal tarsal joints (17 [14%]), suspensory ligament desmitis (15 [13%]), forelimb foot pain with distal tarsal joint osteoarthritis (11 [9%]), and bruised feet (10 [8.5%]). In 81 (69%) horses, the affected joint was treated with intra-articular medications. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in horses used for barrel racing that are examined because of lameness or poor performance, the forelimbs are more likely to be affected than the hind limbs, with forelimb foot pain and osteoarthritis of the distal tarsal joints being the most common underlying abnormalities.     

Arthrographic Analysis of Communication between the Tarsometatarsal and Distal Intertarsal Joints of the Horse

The intra-articular anatomy of 103 equine tarsi was studied by contrast radiography with image intensification and computerized tomography. There was communication between the tarsometatarsal and distal intertarsal joints in 21 of 55 (38%) interpretable tarsometatarsal arthrograms, and in 11 of 48 (23%) interpretable distal intertarsal arthrograms. The difference was not significant. The volume of contrast agent and the pressure of injection did not correlate with communication. Forced injection caused subcutaneous leakage of contrast medium but not communication. Communication occurred via the tarsal canal and the space between the third and the combined first and second tarsal bones. Injection of the distal intertarsal joint from the dorsomedial aspect of the limb, distal to the palpable distal border of the medial branch of the tendon of the tibialis cranialis muscle and between the central, third, and combined first and second tarsal bones, provided reliable access except in the presence of severe periosteal proliferations.     

Changes in kinematic variables observed during pressure-induced forelimb lameness in adult horses trotting on a treadmill

OBJECTIVE: To determine whether kinematic changes induced by heel pressure in horses differ from those induced by toe pressure. ANIMALS: 10 adult Quarter Horses. PROCEDURE: A shoe that applied pressure on the cuneus ungulae (frog) or on the toe was used. Kinematic analyses were performed before and after 2 levels of frog pressure and after 1 level of toe pressure. Values for stride displacement and time and joint angles were determined from horses trotting on a treadmill. RESULTS: The first level of frog pressure caused decreases in metacarpophalangeal (fetlock) joint extension during stance and increases in head vertical movement and asymmetry. The second level of frog pressure caused these changes but also caused decreases in stride duration and carpal joint extension during stance as well as increases in relative stance duration. Toe pressure caused changes in these same variables but also caused maximum extension of the fetlock joint to occur before midstance, maximum hoof height to be closer to midswing, and forelimb protraction to increase. CONCLUSION AND CLINICAL RELEVANCE: Decreased fetlock joint extension during stance and increased head vertical movement and asymmetry are sensitive indicators of forelimb lameness. Decreased stride duration, increased relative stance duration, and decreased carpal joint extension during stance are general but insensitive indicators of forelimb lameness. Increased forelimb protraction, hoof flight pattern with maximum hoof height near midswing, and maximum fetlock joint extension in cranial stance may be specific indicators of lameness in the toe region. Observation of forelimb movement may enable clinicians to differentiate lameness of the heel from lameness of the toe.     

Laser-Facilitated arthrodesis of the distal tarsal joints

Arthritis of the distal tarsal joints is a common cause of lameness in performance horses. Clinical signs of distal tarsal arthritis are variable and may include gait abnormalities typical for tarsal lameness, including accentuated elevation of the affected limb, shortened cranial phase of the stride, and decreased arc of the foot. Affected horses frequently resent palpation of the lumbar and gluteal musculature. The lameness is usually increased after a hind limb flexion test. This condition is most commonly treated with intra-articular injections of sodium hyaluronate and corticosteroids in conjunction with controlled exercise and systemic nonsteroidal anti-inflammatory medication. Horses that are refractory to this form of treatment have traditionally been treated by cunean tenectomy with inconsistent results. Various surgical techniques have been used to achieve arthrodesis of these joints in an effort to eliminate the lameness associated with arthritic changes in these joints. Laser-assisted arthrodesis offers a minimally invasive surgical procedure with a relatively short convalescent period that eliminates the clinical signs of lameness in a high number of cases.     

Diagnosis, relative incidence, and probable cause of cunean tendon bursitis-tarsitis of Standardbred horses

A prospective study of the diagnostic results on 25 previously untreated, slightly lame Standardbred horses showed that manipulative tests are of some help in diagnosis. The lameness of each horse was diminished or the horse went lame on the opposite limb after being given an injection of anesthetic in the cunean bursa, and lameness improved more when local anesthetic was injected in the distal intertarsal and tarsometatarsal articulations. In four horses, lesions of the distal articulation of the hock were evident on radiography.     

Comparison of three methods for arthrodesis of the distal intertarsal and tarsometatarsal joints in horses

OBJECTIVE: To evaluate the effects of diode laser surgery (LS), surgical drilling (SD), and intraarticular sodium monoiodoacetate (MIA) as methods for fusing the distal intertarsal (DIT) and tarsometatarsal (TMT) joints in horses. STUDY DESIGN: Experimental study. ANIMALS: Adult horses (15) without radiographic signs of osteoarthritis (OA) of the DIT and TMT joints. METHODS: Group 1 (n=3) had LS performed bilaterally on DIT and TMT joints; 1 horse was evaluated for 1 week and 2 horses were evaluated for 2 weeks. Group 2 (n=6) had LS on DIT and TMT joints of 1 tarsus and MIA administration into the contralateral DIT and TMT joints and were evaluated for 6 months. Group 3 (n=6) had LS performed on DIT and TMT joints of 1 tarsus and SD of the contralateral DIT and TMT joints and were evaluated for 12 months. Postoperative comfort, lameness, radiography, microradiography, and histology scores were compared using repeated measures ANOVA, and paired or 2 sample t-tests; significance was set at P<.05. RESULTS: LS caused the least postoperative morbidity. In group 2, horses were less lame in 4 LS-treated limbs and 2 MIA-treated limbs at 6 months when compared with the contralateral limb. In group 3, horses were less lame in 5 LS-treated limbs and 1 SD-treated limb at 6 and 12 months compared with the contralateral limb. On microradiography, 11 MIA joints and 2 LS joints had bone bridging the joint at 6 months whereas 8 SD joints and 5 LS joints had bone bridging at 12 months. Significantly more joint space was bridged by bone in MIA- (51.4%) and SD (46.2%)-treated joints compared with LS joints at 6 (30.6%) and 12 (28.5%) months, respectively (P<.05). CLINICAL RELEVANCE: SD and MIA resulted in more bone bridging of the distal 2 tarsal joints, than LS. However, LS seemingly caused less pain and discomfort to horses in the immediate postoperative period; horses were generally less lame in the LS limb. More laser energy may need to be applied to these joints to promote fusion; however, it may also have beneficial effects beyond fusion. Further research on horses with OA of the distal 2 tarsal joints is needed to determine whether LS can cause soundness without facilitating bony fusion.     

The hindlimb in walking horses: 2. Net joint moments and joint powers

The objective of the study was to describe net joint moments and joint powers in the equine hindlimb during walking. The subjects were 5 sound horses. Kinematic and force data were collected synchronously and combined with morphometric information to determine net joint moments at each hindlimb joint throughout stance and swing. The results showed that the net joint moment was on the caudal/plantar side of all hindlimb joints at the start of stance when the limb was being actively retracted. It moved to the cranial/dorsal side around 24% stride at the hip and stifle and in terminal stance at the more distal joints. It remained on the cranial/dorsal side of all joints during the first half of swing to provide active limb protraction, then moved to the caudal/plantar aspect to reverse the direction of limb motion prior to ground contact. The hip joint was the main source of energy generation throughout the stride. It was assisted by the tarsal joint in both stance and swing phases and by the fetlock joint during the stance phase. The coffin joint acted as an energy damper during stance, whereas the stifle joint absorbed almost equal amounts of energy in the stance and swing phases. The coffin and fetlock joints absorbed energy as the limb was protracted and retracted during the swing phase, suggesting that their movements were driven by inertial forces. Future studies will apply these findings to detect changes in the energy profiles due to specific soft tissue injuries.     

Kinematic characteristics of Andalusian, Arabian and Anglo-Arabian horses: a comparative study

The aim of this study was to compare the kinematic trot characteristics of three different breeds of horse: Andalusian (AN, n = 15), Arabian (AR, n = 7) and Anglo-Arabian (AA, n = 5) using standard computer-assisted videography (25 Hz). Linear, temporal and angular parameters in fore- and hind limbs were analysed in six randomly selected strides per horse. Normalised angle-time diagrams along the complete stride were obtained for all joints angles in each breed and specific kinematic characteristics were detected graphically. AA horses displayed longer swing durations in both limbs ans a shorter angular range of motion (ARM) in scapula and pelvis inclination and in shoulder, hip and forelimb retraction-protraction angles. At lift off, stifle and tarsal joint angles were more flexed. In general, only small differences were observed in AR horse kinematics when compared with the other 2 breeds. AN horses presented negative overtracking length, which was positive in AR and AA. In AN horses the elbow and carpal joints were more flexed at the moment of maximal elevation, elbow and fore-fetlock joints also exhibited a larger ARM due to a smaller angle at maximal flexion. In the hind limbs, tarsal, hind fetlock and retraction-protraction angles presented a larger ARM in AN horses due to greater maximal flexion in the tarsal and hind fetlock joints. Fore- and hind fetlocks were also more flexed in horses from this breed. In conclusion, differences between kinematic variables at the trot were observed in the three breeds studied here, mainly in forelimb joints. The most outstanding feature was the greater forelimb flexion recorded in AN horses than in the other breeds which is consistent with the elevated movements in this breed. In AA horses, the ARM of proximal joints involved in retraction protraction in both fore- and hind limbs was smaller. All the differences observed highlighted the idiosyncratic nature of the trot in each breed; this may influence the functional capacity of each breed.     

Fusion of the distal intertarsal and tarsometatarsal joints in the horse using intraarticular sodium monoiodoacetate

Six normal horses received 3 intra-articular injections of sodium monoiodoacetate (MIA) in the distal intertarsal (DIT) and tarsometatarsal (TMT) joints of one hindlimb. Injections were at three week intervals, and post injection pain was controlled with routine administration of phenylbutazone for five days following each injection. All horses underwent a gradually increasing exercise programme consisting of walking and trotting beginning one week after the first injection and continuing for 24 weeks. All treated joints showed increasingly severe radiographic evidence of degenerative joint disease with time. Clinical signs were mild or absent during exercise. All treated joints showed radiographic and histological evidence of fusion 24 weeks after the first injection. Amount of radiographic fusion ranged from 54.49 per cent to 88.64 per cent of the joint space. Histologically, the joint space that appeared radiographically fused was filled mainly with woven and lamellar bone. Fibrocartilage and fibrous tissue was seen frequently in the transition between fused and unfused areas. Articular cartilage in unfused areas was thin, fibrillated, hypocellular and histochemically showed diminished proteoglycan content. Existing joint space was filled with fibrin and necrotic, acellular chondroid matrix. We conclude that MIA will produce fusion of the DIT and TMT joints of normal horses in 24 weeks, and may offer a relatively easy, inexpensive and non-invasive treatment for distal tarsal osteoarthritis in the horse.     

Three-dimensional kinematic analysis of horses with induced tarsal synovitis

REASONS FOR PERFORMING STUDY: Techniques for 3D analysis have recently been developed. This study applied 3D kinematic analysis to describe the effects of lameness in the distal intertarsal (DIT) and tarsometatarsal (TMT) joints; complex joints such as this may show measurable amounts of movement outside the sagittal plane that may change in response to pathological conditions. HYPOTHESIS: Three-dimensional motions of the tarsal joint change after the induction of synovitis at the DIT and TMT joints. METHODS: Twelve retroreflective markers, attached on the skin over the right limb, were used to develop 3D coordinate systems for tibial and metatarsal segments. Data were collected at trot from 4 horses on 2 occasions, before (sound condition) and after (lame condition) induction of synovitis of the DIT and TMT joints. Ranges of 3D motions of the metatarsal segment relative to the tibial segment were compared between sound and lame conditions using t tests. RESULTS: There were significant decreases (P<0.05) in tarsal joint flexion and cranial translation of the metatarsus relative to the tibia during stance, and in proximal translation of the metatarsus during swing. CONCLUSIONS AND POTENTIAL RELEVANCE: In the lame condition, reduced cranial translation at the DIT and TMT joints may lead to a reduction in the motion of the articular cartilage surfaces relative to each other, which may have adverse effects on cartilage nutrition and function. Further studies of tarsal 3D kinematics in horses with bone spavin could allow quantification of the biomechanical effects of the special shoes used for conservative treatment.     

Use of high-speed cinematography and computer generated gait diagrams for the study of equine hindlimb kinematics

High-speed cinematography with computer aided analysis was used to study equine hindlimb kinematics. Eight horses were filmed at the trot or the pace. Filming was done from the side (lateral) and the back (caudal). Parameters measured from the lateral filming included the heights of the tuber coxae and tailhead, protraction and retraction of the hoof and angular changes of the tarsus and stifle. Abduction and adduction of the limb and tarsal height changes were measured from the caudal filming. The maximum and minimum values plus the standard deviations and coefficients of variations are presented in tabular form. Three gait diagrams were constructed to represent stifle angle versus tarsal angle, metatarsophalangeal height versus protraction-retraction (fetlock height diagram) and tuber coxae and tailhead height versus stride (pelvic height diagram). Application of the technique to the group of horses revealed good repeatability of the gait diagrams within a limb and the diagrams appeared to be sensitive indicators of left/right asymmetries.