Objective determination of pelvic movement during hind limb lameness by use of a signal decomposition method and pelvic height differences

OBJECTIVE: To evaluate pelvic movement over a large number of strides in sound horses and in horses with induced hind limb lameness by applying methods to the pelvis that have been described for evaluating vertical head movement in horses with induced forelimb lameness. ANIMALS: 17 adult horses. PROCEDURE: Horses were filmed while trotting on a treadmill before and after induction of transient mild and moderate hind limb lamenesses. Vertical pelvic movement was measured by a signal decomposition method. The vertical pelvic signal was decomposed into a periodic component (A1) that occurred at half the stride frequency (representing vertical pelvic movement caused by lameness) and another periodic component (A2) that occurred at stride frequency (representing normal vertical pelvic movement of a trotting horse). Vertical pelvic and foot positions were correlated for each stride to compare the difference between the minimum and maximum heights of the pelvis during and after stance of the right hind limb to the minimum and maximum heights of the pelvis during and after stance of the left hind limb. RESULTS: Maximum pelvic height difference and lameness amplitude (A1) differed significantly between sound and mild or moderate hind limb lameness conditions. Mean A1 value for vertical pelvic movement in sound horses was less than that previously reported for vertical head movement. CONCLUSION AND CLINICAL RELEVANCE: Pelvic height differences and signal decomposition of pelvic movement can be used to objectively evaluate hind limb lameness in horses over a large number of strides in clinical and research settings.     

Computer-assisted kinematic evaluation of induced compensatory movements resembling lameness in horses trotting on a treadmill

OBJECTIVE: To characterize compensatory movements of the head and pelvis that resemble lameness in horses. ANIMALS: 17 adult horses. PROCEDURE: Kinematic evaluations were performed while horses trotted on a treadmill before and after shoe-induced lameness. Lameness was quantified and the affected limb determined by algorithms that measured asymmetry in vertical movement of the head and pelvis. Induced primary lameness and compensatory movements resembling lameness were assessed by the Friedman test. Association between induced lameness and compensatory movements was examined by regression analysis. RESULTS: Compensatory movements resembling lameness in the ipsilateral forelimb were seen with induced lameness of a hind limb. There was less downward and less upward head movement during and after the stance phase of the ipsilateral forelimb. Doubling the severity of lameness in the hind limb increased severity of the compensatory movements in the ipsilateral forelimb by 50%. Compensatory movements resembling lameness of the hind limb were seen after induced lameness in a forelimb. There was less upward movement of the pelvis after the stance phase of the contralateral hind limb and, to a lesser extent, less downward movement of the pelvis during the stance phase of the ipsilateral hind limb. Doubling the severity of lameness in the forelimb increased compensatory movements of the contralateral hind limb by 5%. CONCLUSIONS AND CLINICAL RELEVANCE: Induced lameness in a hind limb causes prominent compensatory movements resembling lameness in the ipsilateral forelimb. Induced lameness in a forelimb causes slight compensatory movements resembling lameness in the ipsilateral and contralateral hind limbs.     

Kinematics of the hind limb in trotting horses after induced lameness of the distal intertarsal and tarsometatarsal joints and intra-articular administration of anesthetic

OBJECTIVE: To identify hind limb and pelvic kinematic variables that change in trotting horses after induced lameness of the distal intertarsal and tarsometatarsal joints and after subsequent intra-articular administration of anesthetic. ANIMALS: 8 clinically normal adult horses. PROCEDURE: Kinematic measurements were made before and after transient endotoxin-induced lameness of the distal intertarsal and tarsometatarsal joints and after intra-articular administration of anesthetic. Fourteen displacement and joint angle (metatarsophalangeal [fetlock] and tarsal joints) measurements were made on the right hind limb, sacrum, and the right and left tubera coxae. Kinematic measurements were compared by general linear models, using a repeated measures ANOVA. Post hoc multiple comparisons between treatments were evaluated with a Fisher least squared difference test at alpha = 0.05. RESULTS: After lameness induction, fetlock and tarsal joint extension during stance decreased, fetlock joint flexion and hoof height during swing increased, limb protraction decreased, and vertical excursion of the tubera coxae became more asymmetric. After intra-articular administration of anesthetic, limb protraction returned to the degree seen before lameness, and vertical excursion of the tubera coxae became more symmetric. CONCLUSIONS AND CLINICAL RELEVANCE: Increased length of hind limb protraction and symmetry of tubera coxae vertical excursion are sensitive indicators of improvement in tarsal joint lameness. When evaluating changes in tarsal joint lameness, evaluating the horse from the side (to assess limb protraction) is as important as evaluating from the rear (to assess pelvic symmetry).     

Evaluation of a sensor-based system of motion analysis for detection and quantification of forelimb and hind limb lameness in horses

OBJECTIVE: To compare a sensor-based accelerometer-gyroscopic (A-G) system with a video-based motion analysis system (VMAS) technique for detection and quantification of lameness in horses. ANIMALS: 8 adult horses. PROCEDURE: 2 horses were evaluated once, 2 had navicular disease and were evaluated before and after nerve blocks, and 4 had 2 levels of shoe-induced lameness, alternatively, in each of 4 limbs. Horses were instrumented with an accelerometer transducer on the head and pelvis, a gyroscopic transducer on the right forelimb and hind feet, and a receiver-transmitter. Signals from the A-G system were collected simultaneously with those from the VMAS for collection of head, pelvis, and right feet positions with horses trotting on a treadmill. Lameness was detected with an algorithm that quantified lameness as asymmetry of head and pelvic movements. Comparisons between the A-G and VMAS systems were made by use of correlation and agreement (kappa value) analyses. RESULTS: Correlation between the A-G and VMAS systems for quantification of lameness was linear and high (r2 = 0.9544 and 0.8235 for forelimb and hind limb, respectively). Quantification of hind limb lameness with the A-G system was higher than measured via VMAS. Agreement between the 2 methods for detection of lameness was excellent (kappa = 0.76) for the forelimb and good (kappa = 0.56) for the hind limb. CONCLUSIONS AND CLINICAL RELEVANCE: The A-G system detected and quantified forelimb and hind limb lameness in horses trotting on the treadmill. Because the data are collected wirelessly, this system might be used to objectively evaluate lameness in the field.     

Scintigraphic abnormalities of the pelvic region in horses examined because of lameness or poor performance: 128 cases (1993-2000)

OBJECTIVE: To identify scintigraphic abnormalities in the pelvic region of horses examined because of hind limb lameness or poor performance and determine the clinical relevance of areas of abnormal radiopharmaceutical uptake (ARU) in these horses. DESIGN: Retrospective study. ANIMALS: 128 horses. PROCEDURE: Medical records were reviewed, and information on signalment, history, admitting complaints, physical examination findings, and results of lameness examinations was recorded. Clinical relevance of areas of ARU was determined by comparison with results of other diagnostic tests. For horses with clinically relevant areas of ARU, follow-up information was obtained through telephone interviews with owners and trainers and analysis of race records. RESULTS: Areas of ARU were identified in the tuber coxae (25 horses), ischiatic tuber (9), hip joint (10), third trochanter (10), ilium (5), sacral tuber region (22), greater trochanter (1), cranial femoral cortex (1), skeletal muscle surrounding the pelvis (34), or multiple areas (11). In 44 horses, areas of ARU were associated with the primary cause of lameness; in 51, areas of ARU were not associated with the primary cause of lameness; and in 33, the primary cause of lameness was not determined. Thirty-six of the 44 horses with clinically relevant areas of ARU were available for follow-up; 15 (42%) had a good outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that pelvic scintigraphy may be useful in identifying abnormalities in horses with hind limb lameness or poor performance.     

Voluntary limb-load distribution in horses with acute and chronic laminitis

OBJECTIVES: To compare limb-load distribution between horses with and without acute or chronic laminitis. ANIMALS: 10 horses with carbohydrate-induced acute laminitis, 20 horses with naturally occurring chronic laminitis, and 20 horses without foot abnormalities (controls). PROCEDURES: Limb-load distribution was determined, using a custom-designed system that allowed simultaneous quantification of the mean percentage of body weight voluntarily placed on each limb (ie, mean limb load) and the SD of the mean load over a 5-minute period (ie, load distribution profile [LDP]). Load distribution profile was used as an index of frequency of load redistribution. RESULTS: Mean loads on fore- and hind limbs in control horses were 58 and 42%, respectively, and loads were equally and normally distributed between left and right limbs. In addition, forelimb LDP was greater, compared with hind limbs, and was affected by head and neck movement. In comparison, limb-load distribution in horses with chronic laminitis was characterized by an increase in the preferential loading of a forelimb, a decrease in total forelimb load, and an increase in LDP that was correlated with severity of lameness. In horses with carbohydrate-induced acute laminitis, mean limb loads after onset of lameness were not different from those prior to lameness; however, LDP was significantly decreased after onset of lameness. CONCLUSION AND CLINICAL RELEVANCE: Quantification of limb-load distribution may be an applicable screening method for detecting acute laminitis, grading severity of lameness, and monitoring rehabilitation of horses with chronic laminitis.     

Comparison of visual lameness scores to gait asymmetry in racing Thoroughbreds during trot in-hand

Regular monitoring of movement asymmetry with inertial measurement units (IMUs) to aid in the diagnosis of the underlying cause of a lameness is feasible. Normal ranges for specific groups of horses may be required, with consideration of expert veterinary opinions for both asymmetry screening and lameness assessment. The aim of this study was to determine movement asymmetry values compared with expert lameness scores to enable screening for lameness in Thoroughbreds in race training. IMU gait assessment during in-hand trot-up was performed in 25 racehorses undergoing routine gait analysis or lameness examination at the Singapore Turf Club. Video recordings were graded numerically (0–5) for lameness by six experienced racehorse veterinarians. Inter-observer agreement and consistency were determined. Median lameness scores were used to calculate sensitivity and specificity for head, withers and pelvic movement asymmetry. Guideline values for aligning movement asymmetry values with expert opinions about forelimb and hindlimb lameness were determined from receiver operating characteristics (ROC). Inter-observer agreement was poor to fair, inter-observer consistency was good (intraclass correlation coefficient: 0.667 for forelimbs and 0.617 for hindlimbs). ROCs indicated higher discriminative power for hindlimb lameness using pelvic asymmetry (90% sensitivity, 93% specificity) compared with forelimb lameness using head asymmetry (69% sensitivity, 89% specificity) or withers asymmetry (44% sensitivity, 89% specificity). When compared to expert lameness scores from videos of a limited number of Thoroughbred racehorses, preliminary guideline values for movement asymmetry screening for forelimb lameness (>|14.5 mm|) and hindlimb lameness (>|7.5 mm|) are higher than previously reported clinical thresholds of >|7 mm| for head movement and >|4 mm| for pelvic movement asymmetry.     

Pelvic fractures in horses: 19 cases (1974-1984)

The clinical features of 19 horses with pelvic fractures were reviewed. The most common problem was a grade III or IV unilateral hind limb lameness. The prevalence of fractures was greater in females and horses less than 4 years old. All horses were treated with a combination of analgesic administration and stall rest for 2 to 6 months. Seven of 11 horses (64%) available for long-term follow-up evaluation recovered and 4 of 11 (36%) had no lameness when being ridden. Five of seven (71%) horses with fractures that involved the acetabulum recovered, and 4 (57%) had complete resolution of lameness. No correlation was found between the long-term outcome of the horses and the bone fractured, age of horse, or duration of injury before admission.     

Bilateral lameness in horses a kinematic study

Summary

The kinematic pattern of mild bilateral lameness was studied by inducing a supporting limb lameness in both forelimbs of 11 sound Dutch Warmblood horses. The kinematics of the horses were recorded while they trotted (3.5 m/s) on a treadmill. The locomotion analysis system CODA‐3 was used to determine the temporal stride patterns, limb movements as well as head and trunk movement patterns. The transient lameness model, by which pressure‐induced pain is evoked on the hoof sole, was used. Differences between left and right limbs as well as between the sound and the lame condition were tested using a paired t‐test.

Stride and stance duration did not change significantly (p < 0.05) during bilateral lameness compared to the pattern of sound horses. Diagonal advanced placement changed to an earlier placement of both forelimbs. Fetlock hyperextension decreased also in both forelimbs, while the pro‐ and retraction, hoof impact angle, maximal hoof height, and all hind limb variables remained unchanged. Vertical head and trunk movements tended to decrease, but these changes were not significant.

It was concluded that fetlock hyperextension and diagonal advanced placement indicate locomotor disturbances, but that mild bilateral lameness may be difficult to distinguish from individual patterns in single assessments because of the lack of locomotor asymmetries. Evaluation of these variables at regular intervals may allow an early detection of bilateral lameness, which then could be confirmed by diagnostic local anaesthesia.     

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.     

Quantitative assessment of gait parameters in horses: Useful for aiding clinical decision making?

Gait analysis in horses has moved from the laboratory into the outside world enabling researchers and clinicians to make use of quantitative measurements to provide evidence aiding clinical decision making. In this article we explain how the two major visual signs of lameness – head nod and hip hike –are linked to the mechanics of lameness. These parameters should be regarded as well suited for incorporation into clinical decision making being easily measurable e.g. with inertial sensors under nonlaboratory conditions and representative of the underlying mechanical changes. A brief overview of the results of validation studies of the use of inertial sensors for quantification of movement symmetry shows that accuracy, precision and repeatability with current sensor generations are in the order of 3–7 mm; this is below the reported detection threshold for movement symmetries ‘by eye’. Recent studies with inertial sensors have investigated conditions relevant to the clinical lameness examination: lungeing, flexion tests and diagnostic analgesia. Lungeing introduces kinematic adaptations rendering head and pelvic movement asymmetrical, even in sound horses. First guideline values are available for changes after flexion tests and diagnostic analgesia, and we understand which parameters show consistent changes. This is crucial for investigating the effects in horses with different orthopaedic deficits. In conclusion, the current inertial sensor systems, while not quantifying all the gait adaptations seen in lame horses, characterise the major mechanical changes affecting fore‐ and hindlimb lame horses. In order to avoid misinterpretation of the generated data, users should have a thorough understanding of the gait parameters and be aware of sensor limitations in terms of accuracy, precision and repeatability.     

Lameness, athletic performance, and financial returns in yearling Thoroughbreds bought for the purpose of resale for profit

OBJECTIVE: To characterize lameness during training and compare exercise variables and financial returns among yearling Thoroughbreds that were bought for the purpose of resale for profit. ANIMALS: 40 yearling Thoroughbreds. DESIGN: Prospective study. PROCEDURES: Horses purchased at yearling sales (summer 2004) were trained prior to resale at 2-year-olds in training sales (spring 2005). Horses were monitored daily for diagnosis and treatment of lameness during training. Selected variables, including sex, age, purchase price, lameness, distance (No. of furlongs) galloped during training, and financial returns, were compared among horses that had performance speeds (assessed at 2-year-olds in training sales) classified as fast, average, or slow. RESULTS: 37 of 40 horses became lame during training, most commonly because of joint injury. Eighteen of the lame horses had hind limb injuries only; 5 horses had injuries in forelimbs and hind limbs. The frequency of new cases of lameness increased as the date of the 2-year-olds in training sales approached. At the sales, 4, 21, and 15 horses were classified as fast, average, or slow, respectively; median financial return was slightly (but significantly) different among horses classified as fast ($14,000), average ($0), or slow (-$8,000). CONCLUSIONS AND CLINICAL RELEVANCE: Incidence of lameness during training in yearling horses purchased for the purpose of resale for profit was high. Lameness more commonly affected hind limbs than forelimbs and was attributable to joint injury in most horses. Financial returns differed between horses classified as fast and average or slow at the 2-year-olds in training sales.     

Lameness and poor performance in horses used for team roping: 118 cases (2000-2003)

OBJECTIVE: To determine the types of musculoskeletal problems that result in lameness or poor performance in horses used for team roping and determine whether these problems are different in horses used for heading versus heeling. DESIGN: Retrospective study. ANIMALS: 118 horses. PROCEDURE: Medical records of team roping horses that were evaluated because of lameness or poor performance were reviewed to obtain information regarding signalment, primary use (ie, head horse or heel horse), history, results of physical and lameness examinations, diagnostic tests performed, final diagnosis, and treatment. RESULTS: Among horses evaluated by lameness clinicians, the proportion with lameness or poor performance was significantly greater in horses used for heading (74/118) and lower in horses used for heeling (44/118) than would be expected under the null hypothesis. Most horses examined for poor performance were lame. A significantly greater proportion of horses used for heading had right forelimb lameness (26/74 [35%]), compared with horses used for heeling (7/44 [16%]). Horses used for heading had more bilateral forelimb lameness (18/74 [24%]), compared with horses used for heeling (4/44 [9%]). Horses used for heeling had more bilateral hind limb lameness (3/44 [7%]), compared with horses used for heading (0%). The most common musculoskeletal problems in horses used for heading were signs of pain limited to the distal sesamoid (navicular) area, signs of pain in the navicular area plus osteoarthritis of the distal tarsal joints, and soft tissue injury in the forelimb proximal phalangeal (pastern) region. Heeling horses most commonly had signs of pain in the navicular area, osteoarthritis of the metatarsophalangeal joints, and osteoarthritis of the distal tarsal joints. CONCLUSIONS AND CLINICAL RELEVANCE: Horses used for heading were most commonly affected by lameness in the right forelimb. Horses used for heeling had more bilateral hind limb lameness than horses used for heading.     

Desmitis of the straight sesamoidean ligament in horses: 9 cases (1995-1997)

OBJECTIVE: To determine clinical signs, diagnostic findings, and outcome for horses with desmitis of the straight sesamoidean ligament (SSL) near its insertion on the middle phalanx. DESIGN: Retrospective study. ANIMALS: 9 horses. PROCEDURE: Medical records were reviewed, and information on signalment, history, clinical signs, diagnostic findings, and treatment was obtained. Follow-up information was obtained through telephone conversations with owners. RESULTS: In all horses, the diagnosis was made by use of high-resolution ultrasonography. Seven horses had moderate lameness on initial examination; lameness was exacerbated in 6 horses following flexion of the distal limb joints. The cause of lameness could not be determined on the basis of clinical signs, and diagnostic local anesthesia was necessary to localize the source of lameness to the distal portion of the limb. Five horses had forelimb involvement (1 bilateral), and 4 had hind limb involvement (1 bilateral). Treatment consisted primarily of a 6-month rest and rehabilitation program. Six of the 9 horses were able to return to their intended use. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that injury to the SSL proximal to its insertion on the middle phalanx should be considered as a possible cause of lameness in horses, particularly performance horses, with lameness localized to the distal portion of the forelimb or hind limb that do not have any radiographic abnormalities. High-resolution ultrasonography was necessary to make the diagnosis. Horses with an acute injury appeared to have a reasonable chance of responding to treatment and returning to their intended use.     

RADIOGRAPHIC APPEARANCE OF EQUINE LUMBOSACRAL AND PELVIC ABNORMALITIES BY LINEAR TOMOGRAPHY

Radiologic findings are described in 20 horses with clinical signs of a caudal lumbar or hindlimb problem; the horses were subjected to linear tomography of the lumbosacral and pelvic regions. The cases could be divided into four groups: sacroiliac arthrosis (6 horses), lumbosacral abnormalities (3 horses), pelvic or lumbar fracture (6 horses), and no radiographic abnormalities (5 horses). Five of the six horses with sacroiliac arthrosis had spur formation, with localized arthrosis at the caudal aspect of the sacral wing and its articulation with the auricular surface of the ilium. In one horse these lesions were confirmed at postmortem examination. The sixth horse, a Standardbred trotter, had more even and widespread arthrosis of the sacroiliac joint. The three lumbosacral abnormalities were present in two horses with fusion of the L₅-L₆ articulation and one horse with a wider than normal sacrolumbar articulation. Linear tomography also proved to be of diagnostic and prognostic value in the evaluation of lumbar and pelvic fractures. Finally, tomography could be used to eliminate the presence of sacroiliac or lumbosacral damage in some horses that presented with clinical signs suggestive of disease of the lumbosacral or sacroiliac region.     

Agreement between two inertial sensor gait analysis systems for lameness examinations in horses

Gait analysis is gaining popularity for quantification of lameness and 2 commonly used inertial sensor systems assess trunk movement symmetry: can these be used interchangeably in multi‐centre studies? We compared head and pelvic movement symmetry between 2 inertial sensor gait analysis systems in 13 horses equipped simultaneously with the 2 systems. The first system quantified dorsoventral movement in the local reference frame (System A) and the second system global vertical movement (System B). Widths of limits of agreement were calculated employing a well established regression method dealing with systematically changing differences over the range of measured values. Widths of limits of agreement between Systems A and B were narrower for pelvic movement than head movement. For head movement, they ranged from 6.4 to 6.9 mm for in‐hand trot and from 7.3 to 9.7 mm on the lunge and for pelvic movement from 2.5 to 4.4 mm in‐hand and from 3.6 to 5.3 mm on the lunge. Widths of limits of agreement between the 2 investigated inertial sensor gait analysis systems are of comparable magnitude (some equivalent, some marginally higher) to the currently proposed thresholds of 6 mm for head and 3 mm for pelvic movement used in lameness investigations. Differences in measurements with 2 different systems (A and B) obtained from the same horse falling within the reported values should not be seen as a sign of a change in lameness.     

ULTRASONOGRAPHIC FINDINGS IN THE LUMBOSACRAL JOINT OF 43 HORSES WITH NO CLINICAL SIGNS OF BACK PAIN OR HINDLIMB LAMENESS

The transrectal ultrasonographic appearance of the lumbosacral joint was assessed in 43 horses with no history or clinical evidence of back pain or hindlimb lameness. In the majority of horses (34/43, 79.1%) the lumbosacral disc had uniform or mildly heterogeneous echogenicity. However, variation in the ultrasonographic appearance of the lumbosacral joint was also identified, including hyperechogenic regions within the lumbosacral disc with or without an acoustic shadow, and mild or moderate irregularity of the opposing surfaces of the last lumbar and the first sacral vertebral bodies. Marked irregularity of the bony surfaces or marked disruption of the lumbosacral disc was not seen in any horse. The mean distance between the ventral aspects of the last lumbar and first sacral vertebrae was 14.2 mm (range: 7.1–26.5 mm, median: 14.4 mm). The degree of protrusion of the ventral aspect of the lumbosacral disc ranged from 0 to 5 mm (mean: 1.32 mm, median: 1.2 mm). The mean angle between the ventral surfaces of the last lumbar and first sacral vertebrae was 147° (range: 118–165°, median: 150°). There was no significant effect of age, breed, gender, or the size of the horses on either subjective findings in the lumbosacral joint or objective measurements.