In vivo fluoroscopic kinematography of dynamic radio-ulnar incongruence in dogs

Microcomputed tomographic analysis of the ulnar trochlear notch in medium- and large-breed canine cadavers with and without medial coronoid disease

Medial coronoid disease (MCD) is a common disease often associated with thoracic limb lameness in medium- and large-breed dogs. The term MCD includes subchondral changes of the medial coronoid process (MCP), as well as pathologies of both cartilaginous surfaces. As there are only a few comprehensive and detailed studies on the trabecular structure of the medial coronoid, the goal of this study was to compare the trabecular structure of the ulnar trochlear notch of canine cadavers with and without MCD using different micro-computed tomographic (micro-CT) parameters. Fifty-eight elbow joints from 29 canine cadavers of MCD-predisposed and non-predisposed breeds (control group) were examined radiographically, macroscopically and by microcomputed tomography. The study included elbow joints of eight Labrador Retrievers (21.6-37 kg), seven Golden Retrievers (26.3-42 kg), seven Bernese Mountain dogs (31-47 kg) and seven dogs of non-predisposed breeds (19.7-52 kg) (control group). The final diagnosis of MCD was based on necropsy and micro-computed tomographic examinations. Micro-CT examinations were performed using XtremeCT II (Scanco Medical, Zurich, Switzerland) and the following parameters were examined: bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N), connectivity density (Conn.D) and degree of anisotropy (DA). Twenty-four elbows of 44 elbows of the predisposed breeds (Labrador Retrievers, Golden Retrievers Bernese Mountain dogs) showed subchondral changes and lesions of the cartilage surfaces. The result of this study is a higher density (BV/TV) of the trabecular bone of the ulnar trochlear notch in elbows affected by MCD compared to the control group. The increased density due to trabecular reconstruction in the ulnar trochlear notch is likely the result of selectively increased loading during life.

Performing a Three-Dimensional Finite Element Analysis (FEA) to Simulate and Quantify the Contact Pressure in the Canine Elbow Joint: A Pilot Study

OBJECTIVE

 The aim of this study was to measure surface pressures and force distribution on radius and ulna in healthy and dysplastic elbow joints in different positions using the finite element analysis (FEA).

STUDY DESIGN

 FEA was performed on computed tomographic data of healthy and fragmented coronoid process diseased elbow joints of Labrador Retrievers. It considered the articular cartilage, collateral ligaments, triceps and biceps muscle. The analysis of each joint was performed in four positions (standing position: 145 degrees and three positions of the stance phase of gait: beginning: 115 degrees, middle: 110 degrees, end: 145 degrees joint angle) in consideration of different ground reaction forces (standing: 88.3 N; stance phase of gait: 182.5 N).

RESULTS

 Mean values of total force of 317.5 N (standing), 590.7 N (beginning), 330.9 N (middle) and 730.9 N (end) were measured. The percentual force distribution resulted in a total of 49.56 ± 26.58% on the ulna with a very inhomogeneous distribution. A significant difference was detected between the positions 'standing' and 'end' (p = 0.0497) regardless of the joint condition. In some FEA results, visual assessment of the surface pressures indicated an increase in pressure in the region of the medial compartment without a uniform pattern. An increase in pressure resulted in an area increase in the pressure marks on the joint surface and measurable pressure was increased at a larger joint angle.

CLINICAL SIGNIFICANCE

 FEA can provide information about the transmission of force in the joint. Prior to the use of FEA in scientific clinical research for the simulation of force, further model improvements are necessary.

Effect Of Elbow Angle And Weight-Bearing On The Evaluation Of Joint Congruence In Dogs

Joint congruence is relevant for the assessment of elbow dysplasia, a development disorder in dogs. However, quantification of its variation with joint angle and weight bearing, important factors in quadrupedal locomotion, is lacking. Our objective was to estimate those effects on the alignment of humeroradioulnar joint surfaces. The usual protocol for screening elbow dysplasia, including mediolateral extended and flexed elbow views, was preceded by a weight-bearing lateromedial standing radiographic view, without sedation. Minimum distances were measured at established points of the humeroradioulnar joints classified with a grade zero of dysplasia. Sixty elbows (30 Portuguese Pointer dogs) were studied. The joint space between the anconeal process and the ulnar trochlear notch increased with flexion, decreasing with weight bearing (P<0.001). The distance between the humeral trochlea and the trochlear notch at the widest point, increased with weight bearing, while it decreased with flexion. Step and distance between the radial head and the base of the medial coronoid process increased with flexion and decreased with weight bearing. At this point, physiological changes occurred at the humeroulnar joint space. The methodology allowed to quantify the variations on joint spaces with the elbow angle and weight bearing, important for the interpretation of congruence in diagnosis and treatment of dysplasia. Reference absolute and indexed values obtained allow future comparisons with other breeds and dysplastic dogs. Physiological variations denoted that radioulnar joint became more incongruent under flexion, and more congruent under weight bearing, while humeroulnar joint became more congruent under flexion, and more incongruent under weight bearing.

Clinical and Radiographic Evaluation of Short- and Long-Term Outcomes of Different Treatments Adopted for Elbow Medial Compartment Disease in Dogs

Medial compartment disease is a common occurrence in dogs affected by elbow dysplasia. Despite many treatments suggested in the literature, only few studies reported comparative outcomes in the short and long term. The aim of this study is to report and compare short- and long-term clinical and radiographic outcomes of dogs treated for medial compartment disease (MCD) by distal dynamic ulnar ostectomy (DUO), bi-oblique dynamic proximal ulnar osteotomy (BODPUO) and conservative management (CM). From 2016 to 2018, all medium to large dogs, aged between 5 and 12 months, affected by uni/bilateral MCD and treated by DUO, BODPUO or CM, were enrolled in this study and followed up for 24 months. Orthopedic and radiographic examinations were performed at T₀, T₂, T₁₂ and T₂₄ months after treatment. Lameness score, elbow arthralgia, elbow range of motion (ROM), osteoarthritis (OA) score and percentage of ulnar subtrochlear sclerosis (%STS) were evaluated at each time point. According to the treatment performed, dogs were divided into three groups: DUO, BODPUO and CM. Forty-five elbows from twenty-six dogs, treated with DUO (n = 17), BODPUO (n = 17) or CM (n = 11), were prospectively enrolled in the study. The patients enrolled in the CM group were older and showed more severe radiographic signs of OA, compared to those enrolled in the other two groups. Lameness and arthralgia scores (p < 10⁻⁴) were significantly decreased in patients that underwent surgical treatment and increased in patients managed conservatively (lameness p < 10⁻⁴, arthralgia p = 0.3068), at T₁₂ and T₂₄. OA score (p < 0.0040) and ROM (DUO, CM p < 10⁻⁴; BODPUO p = 0.0740) worsened in every study group, but %STS decreased in DUO (p = 0.0108), increased in the CM group (p = 0.0025) and remained unchanged in the BODPUO group (p = 0.2740). This study supports the clinical efficacy of DUO and BODPUO in reducing lameness, arthralgia and progression of %STS. Early diagnosis and surgical attention in patients affected by MCD can improve the short- and long-term outcome and reduce the progression of secondary changes.

Computed tomographic assessment of the completeness of arthroscopic subtotal coronoidectomy in dogs with medial coronoid disease

BACKGROUND

Until recent years, arthroscopic subtotal coronoidectomy has been the universally accepted treatment for medial coronoid disease but has variable clinical outcomes. The aim of this study was to evaluate the completeness of arthroscopic medial coronoid debridement and to detect the most vulnerable location of failure.

METHODS

Eighty-three dogs with a diagnosis of medial coronoid disease were included in the study. Arthroscopic debridement was performed in 92 elbow joints, and the completeness of removal was assessed by postoperative computed tomography scans.

RESULTS

Pathological changes were confined to the coronoid apex in 92/92 (100%) of cases and combined with radial incisure lesions in 39/92 (42%). Apical lesions were completely removed in 66/92 (72%) of cases and radial incisure lesions in 2/39 (5%). Bony remnants were detected at the apex (46%) and base (24%) of the medial coronoid process, free within the elbow joint (9%), and/or within the instrument port (84%). Fissures were positively associated with the occurrence of bony remnants (p = 0.038) and a 37% higher probability of incomplete removal of radial incisure lesions (p = 0.001).

CONCLUSION

In this study, incomplete removal was more likely to occur in the presence of radial incisure lesions. Thorough assessment of this region during arthroscopy is strongly recommended.

Biomechanics of the Canine Elbow Joint

The canine elbow joint is a complex joint, whose musculoskeletal anatomy is well investigated. During the last 30 years kinematic analysis has gained importance in veterinary research and kinematics of the healthy and medial coronoid disease affected canine elbow joint are progressively investigated. Video-kinematographic analysis represents the most commonly used technique and multiple studies have investigated the range of motion, angular velocity, duration of swing and stance phase, stride length and other kinematic parameters, mostly in the sagittal plane only. However, this technique is more error-prone and data gained by video-kinematography represent the kinematics of the whole limb including the soft tissue envelope. A more precise evaluation of the in vivo bone and joint movement can only been achieved using fluoroscopic kinematography. Based on recent studies significant differences in the motion pattern between healthy joints and elbows with medial coronoid disease could be detected. Thereby not only adaptive changes, caused by pain and lameness, could be described, but primary changes in the micromotion of the joint forming bones could be found, which potentially represent new factors in the pathogenesis of medial coronoid disease. This chapter gives a review of current literature on elbow joint kinematics, with particular focus onto pathologic biomechanics in dysplastic canine elbows.

Relation of Computed Tomography-Based Static Axial Radioulnar Incongruence Measurements under General Anaesthesia and Dynamic, In Vivo RUI during the Walk in Canine Elbow Joints with and without Medial Coronoid Process Disease

OBJECTIVE

 This study aimed to evaluate the correlation of static axial radioulnar incongruence (sRUI) measured under general anaesthesia with the real in vivo dynamic RUI (dRUI) during walking.

STUDY DESIGN

 This was a prospective clinical study that included 6 sound elbows (5 dogs) and 7 medial coronoid process disease (MCPD) affected elbows (6 dogs).

MATERIALS AND METHODS

 Static axial radioulnar incongruence was measured using the sphere fitting technique on computed tomography-based three-dimensional (3D) models of radius and ulna. The in vivo pose of radius and ulna was derived from radiostereometric analysis during the walk and transferred onto previously calculated 3D models. Dynamic RUI was measured on those adjusted models using the sphere fitting technique, providing a measurement of RUI over time during walk.

RESULTS

 Mean sRUI was 0.2 mm (standard deviation [SD]: 0.30) in control and 1.4 mm (SD: 0.73) in elbow joints with MCPD; being significantly different (p = 0.0035; confidence interval [CI]: 0.4772-1.8824). Mean dRUI in controls (-0.4 mm; SD: 0.47) was significantly different (p = 0.0004; CI: 0.9918-2.5225) from dRUI in the affected elbows (1.4 mm; SD: 0.73). Comparison of sRUI and dRUI within each group showed difference in the control group (0.2 vs. -0.4 mm; p = 0.0138; CI: 0.1820-1.0014). In affected elbows, no difference between sRUI and dRUI was found (1.4 vs. 1.4 mm; p = 0.8963).

CONCLUSION

 In normal elbow joints, sRUI does not represent the in vivo condition during weight bearing. Dynamic and slightly negative RUI occurs during loading (0.2 mm positive to -0.4 mm negative RUI). In MCPD affected elbows with sRUI, no dynamic change of RUI occurs during the walk.

Biplanar High-Speed Fluoroscopy of Pony Superficial Digital Flexor Tendon (SDFT)-An In Vivo Pilot Study

The superficial digital flexor tendon (SDFT) is the most frequently injured structure of the musculoskeletal system in sport horses and a common cause for early retirement. This project's aim was to visualize and measure the strain of the sound, injured, and healing SDFTs in a pony during walk and trot. For this purpose, biplanar high-speed fluoroscopic kinematography (FluoKin), as a high precision X-ray movement analysis tool, was used for the first time in vivo with equine tendons. The strain in the metacarpal region of the sound SDFT was 2.86% during walk and 6.78% during trot. When injured, the strain increased to 3.38% during walk and decreased to 5.96% during trot. The baseline strain in the mid-metacarpal region was 3.13% during walk and 6.06% during trot and, when injured, decreased to 2.98% and increased to 7.61%, respectively. Following tendon injury, the mid-metacarpal region contributed less to the overall strain during walk but showed increased contribution during trot. Using this marker-based FluoKin technique, direct, high-precision, and long-term strain measurements in the same individual are possible. We conclude that FluoKin is a powerful tool for gaining deeper insight into equine tendon biomechanics.

The effect of the interosseous ligament and selected antebrachiocarpal ligaments on rotation of the radius during extension of the carpus

OBJECTIVE

To evaluate the effect of the interosseous ligament and selected antebrachiocarpal ligaments on the internal rotation of the radius relative to the ulna, during carpal extension.

STUDY DESIGN

Cadaveric study.

SAMPLE POPULATION

Twenty-four cadaveric canine forelimbs.

METHODS

Twenty-four forelimbs were disarticulated at the elbow joint and the antebrachia were prepared for testing. The forelimbs were divided to 6 groups, defined by the order in which ligaments were transected. All specimens were tested intact and after transecting each of the ligaments with the order defined by the group. Rotation of the radius relative to the ulna, caused by extension of the carpus, was measured using a sensor connected to the radius.

RESULTS

The mean(±sd) maximum internal rotation of the radius (5.94° ± (1.23°)) with all the ligaments intact was significantly greater (p < 0.012) than the mean(±sd) maximum internal rotation of the radius (3.13° (± 1.13°)) after transecting the interosseus ligament. Transecting the interosseous ligament subsequent to one of the other ligaments caused a decrease in internal radial rotation (p = 0.629), while, transecting the short radial collateral ligament caused an increase in radial rotation (p = 0.629). Transecting the palmar radiocarpal and ulnocarpal ligaments had no effect on radial rotation.

CONCLUSION

The interosseous ligament was stretched with internal rotation of the radius due to carpal extension. Carpal flexion resulted in external rotation of the radius. This effect was lost when the interosseus ligament was transected.

CLINICAL SIGNIFICANCE

Rotation of the radius is associated with carpal extension, and is likely an intrinsic part of forelimb biomechanics.

Comparison of a novel extracapsular suture technique with a standard fabellotibial suture technique for cranial cruciate ligament repair using a custom-made limb-press model in cats

OBJECTIVES

The aim of our study was to compare the standard fabellotibial suture with Mini TightRope fixation for the treatment of a cranial cruciate ligament (CCL) rupture using a feline custom-made limb press.

METHODS

Cadaveric hindlimbs of 10 cats were inserted in the limb press at predefined joint angles and loads of 10% and 30% body weight (BW) were applied. Mediolateral radiographs were taken and three-dimensional coordinates were recorded using a microscribe digitiser, with intact and transected CCLs and after either fabellotibial suture or Mini TightRope fixation were performed. Different distances and angles from radiographs or microscribe coordinates were analysed.

RESULTS

Radiographic distances from the femoral condyle to the cranial edge of the tibia (X1-X2) were higher in CCL-deficient stifles than in intact stifles at 10% and 30% BW loads. All fabellotibial sutures and Mini TightRope fixations neutralised excessive cranial tibial thrust. A significant difference in the distance between the patella and tibial tuberosity (D2) was observed between CCL-deficient limbs and Mini TightRope-fixed limbs at 10% BW load (P <0.04). A significant difference in the distance between the tibial tuberosity and lateral collateral ligament of the femur (D3) was observed between the intact and transected CCLs on the left legs at 10% BW load (P <0.003) and on both legs at 30% BW load (P <0.002). Furthermore, we observed significant differences between CCL-deficient left legs and Mini TightRope-treated legs at 10% BW load (P <0.003). With regard to fabellotibial suture-treated legs, we observed significant differences between transected limbs and fixed limbs at 30% BW load (P <0.004). W1 (craniocaudal angle) and W2 (mediolateral angle) showed significant differences between intact and transected CCLs and between transected and fixed limbs at 30% BW load (P <0.004).

CONCLUSIONS AND RELEVANCE

Fixation of CCL-deficient stifles with lateral fabellotibial suture, as well as Mini TightRope tightened with a 20 N load, produces good biomechanical stability, as detected via radiographic assessment.

Force Distribution in the Canine Proximal Radio-Ulnar Joint on Extension of the Carpal Joint: A Cadaveric Study

OBJECTIVE

 The aim of this study was to measure the load on the lateral and medial aspects of the proximal radio-ulnar joint during extension of the carpus.

STUDY DESIGN

 This was an ex vivo biomechanical study.

SAMPLE POPULATION

 Twenty-two cadaveric Greyhound thoracic limbs were used.

METHODS

 Twenty-two paired thoracic limbs were used. The olecranon was attached to a custom jig with the foot resting on a stationary anvil. Load sensors were inserted into the proximal radio-ulnar joint, between the radial head and the lateral coronoid process, and between the radial head and the medial coronoid process. Specimens were tested under compression with measurements taken at 0, 4, 9 and 13.5 mm of axial displacement. Data collected at each point included forces on the specimen and medial and lateral coronoid processes as well as the angle of carpal joint extension.

RESULTS

 A linear mixed effects model relating load on the specimen and carpal joint extension angle had an R-squared value of 0.66, and load at the level of the medial coronoid process and angle of carpal extension had an R-squared value of 0.61. There was a significant difference in the loads measured on the lateral and medial coronoid processes at all angles (p < 0.0001).

CONCLUSION

 Extension of the carpus results in asymmetric loading of the proximal radio-ulnar joint.

CLINICAL SIGNIFICANCE

 The findings of this study show that loading of the medial coronoid process may be more complex than originally thought and supports the future investigation of novel management and therapeutic options for affected patients.

CT evaluation of elbow congruity in dogs: radial incisure versus apical medial coronoid process fragmentation

OBJECTIVES

To compare elbow congruity in two cohorts of Labrador retrievers affected with either radial incisure or apex fragmentation of the medial coronoid process.

MATERIALS AND METHODS

Dogs were included if they had elbow lameness and a CT diagnosis of a fissure or fragmentation of the medial coronoid process occurring either along the radial incisure or at the coronoid apex. Radioulnar joint space was measured incrementally from the lateral to the medial coronoid process on transverse slice images. Axial radioulnar congruency was also measured at the apex and mid-coronoid in the dorsal plane and at the base of the coronoid in the sagittal plane.

RESULTS

We studied 99 elbows (in 66 dogs) of which 56 had a fissure or fragmentation along the radial incisure and 43 had an apical fragment. No difference was found between the two groups at the different measuring points - with the exception of a transverse plane radioulnar joint space measurement in the radial incisure group that was smaller adjacent to the lateral coronoid process.

CLINICAL SIGNIFICANCE

Abnormal ulnar morphology in the radial incisure group could result in a fulcrum effect within the radioulnar joint, overloading the radial incisure and predisposing to osteochondral damage at this site.

Radial torsion in dogs with medial compartment disease

OBJECTIVE

To evaluate the magnitude and direction of radial torsion (RT) in dogs with medial compartment disease (MCD).

STUDY DESIGN

Case-control study.

SAMPLE POPULATION

Twenty-eight healthy dogs and 28 dogs with confirmed MCD.

METHODS

Computed tomography images of each dog's antebrachium were evaluated. Radial torsion was measured by using previously described landmarks on the proximal and distal radius. Differences between groups were tested with Student's t tests and Wilcoxon rank-sum tests.

RESULTS

Healthy dogs had a mean RT angle of 3.44° (range, 1.28°-5.44°). Dogs with MCD had a mean RT angle of 11.84° (range, 2.31°-26.55°). Both groups included similar proportions of dogs with external (76% vs 77%) and internal (24% vs 23%) torsion. The direction of torsion (P = .21 and P = .69) did not appear to affect the magnitude of the RT angle.

CONCLUSION

Dogs with MCD had an increased RT angle compared with healthy controls. The direction of torsion varied similarly between groups regardless of the disease status of dogs in this study.

CLINICAL SIGNIFICANCE

The fourfold increase in the RT seen in dogs with MCD may contribute to the rotational overload proposed recently, potentially modifying the orientation of the elliptical radial head and the ligaments crossing the elbow joint.