Mechanical strength of four allograft fixation techniques for ruptured cranial cruciate ligament repair in dogs

Intra-Articular Surgical Reconstruction of a Canine Cranial Cruciate Ligament Using an Ultra-High-Molecular-Weight Polyethylene Ligament: Case Report with Six-Month Clinical Outcome

The intra-articular reconstruction of the cranial cruciate ligament (CrCL) by an organic graft or a synthetic implant allows the restoration of physiological stifle stability. This treatment is still marginal in routine practice. A Rottweiler presented an acute complete CrCL rupture treated using an ultra-high-molecular-weight polyethylene (UHMWPE) implant. The latter was positioned under arthroscopic guidance and fixed with interference screws through femoral and tibial bone tunnels. The dog was weight-bearing just after surgery and resumed normal standing posture and gait after one month, with mild signs of pain upon stifle manipulation. At three months postoperatively, minimal muscle atrophy and minimal craniocaudal translation were noted on the operated hindlimb, with no effects on the clinical outcome. The stifle was painless. At six months postoperatively, standing posture and gait were normal, muscle atrophy had decreased, the stifle was painless, and the craniocaudal translation was stable. On radiographs, congruent articular surfaces were observed without worsening of osteoarthrosis over the follow-up, as well as stable moderate joint effusion. Replacement of a ruptured CrCL with a UHMWPE ligament yielded good functional clinical outcome at six months postoperatively. This technique could be considered an alternative for the treatment of CrCL rupture in large dogs, but it needs confirmation from a prospective study with more dogs.

Evaluation of tendon and ligament microstructure and mechanical properties in a canine model of mucopolysaccharidosis I

Mucopolysaccharidosis (MPS) I is a lysosomal storage disorder characterized by deficient alpha-l-iduronidase activity, leading to abnormal accumulation of glycosaminoglycans (GAGs) in cells and tissues. Synovial joint disease is prevalent and significantly reduces patient quality of life. There is a strong clinical need for improved treatment approaches that specifically target joint tissues; however, their development is hampered by poor understanding of underlying disease pathophysiology, including how pathological changes to component tissues contribute to overall joint dysfunction. Ligaments and tendons, in particular, have received very little attention, despite the critical roles of these tissues in joint stability and biomechanical function. The goal of this study was to leverage the naturally canine model to undertake functional and structural assessments of the anterior (cranial) cruciate ligament (CCL) and Achilles tendon in MPS I. Tissues were obtained postmortem from 12-month-old MPS I and control dogs and tested to failure in uniaxial tension. Both CCLs and Achilles tendons from MPS I animals exhibited significantly lower stiffness and failure properties compared to those from healthy controls. Histological examination revealed multiple pathological abnormalities, including collagen fiber disorganization, increased cellularity and vascularity, and elevated GAG content in both tissues. Clinically, animals exhibited mobility deficits, including abnormal gait, which was associated with hyperextensibility of the stifle and hock joints. These findings demonstrate that pathological changes to both ligaments and tendons contribute to abnormal joint function in MPS I, and suggest that effective clinical management of joint disease in patients should incorporate treatments targeting these tissues.

Dose-dependent effects of enzyme replacement therapy on skeletal disease progression in mucopolysaccharidosis VII dogs

Mucopolysaccharidosis (MPS) VII is an inherited lysosomal storage disorder characterized by deficient activity of the enzyme β-glucuronidase. Skeletal abnormalities are common in patients and result in diminished quality of life. Enzyme replacement therapy (ERT) for MPS VII using recombinant human β-glucuronidase (vestronidase alfa) was recently approved for use in patients; however, to date there have been no studies evaluating therapeutic efficacy in a large animal model of MPS VII. The objective of this study was to establish the effects of intravenous ERT, administered at either the standard clinical dose (4 mg/kg) or a high dose (20 mg/kg), on skeletal disease progression in MPS VII using the naturally occurring canine model. Untreated MPS VII animals exhibited progressive synovial joint and vertebral bone disease and were no longer ambulatory by age 6 months. Standard-dose ERT-treated animals exhibited modest attenuation of joint disease, but by age 6 months were no longer ambulatory. High-dose ERT-treated animals exhibited marked attenuation of joint disease, and all were still ambulatory by age 6 months. Vertebral bone disease was recalcitrant to ERT irrespective of dose. Overall, our findings indicate that ERT administered at higher doses results in significantly improved skeletal disease outcomes in MPS VII dogs.

Proteomics identifies novel biomarkers of synovial joint disease in a canine model of mucopolysaccharidosis I

Mucopolysaccharidosis I is a lysosomal storage disorder characterized by deficient alpha-L-iduronidase activity, leading to abnormal accumulation of glycosaminoglycans in cells and tissues. Synovial joint disease is prevalent and significantly reduces patient quality of life. There is a critical need for improved understanding of joint disease pathophysiology in MPS I, including specific biomarkers to predict and monitor joint disease progression, and response to treatment. The objective of this study was to leverage the naturally-occurring MPS I canine model and undertake an unbiased proteomic screen to identify systemic biomarkers predictive of local joint disease in MPS I. Synovial fluid and serum samples were collected from MPS I and healthy dogs at 12 months-of-age, and protein abundance characterized using liquid chromatography tandem mass spectrometry. Stifle joints were evaluated postmortem using magnetic resonance imaging (MRI) and histology. Proteomics identified 40 proteins for which abundance was significantly correlated between serum and synovial fluid, including markers of inflammatory joint disease and lysosomal dysfunction. Elevated expression of three biomarker candidates, matrix metalloproteinase 19, inter-alpha-trypsin inhibitor heavy-chain 3 and alpha-1-microglobulin, was confirmed in MPS I cartilage, and serum abundance of these molecules was found to correlate with MRI and histological degenerative grades. The candidate biomarkers identified have the potential to improve patient care by facilitating minimally-invasive, specific assessment of joint disease progression and response to therapeutic intervention.

Outcome of cranial cruciate ligament replacement with an enhanced polyethylene terephthalate implant in the dog: A pilot clinical trial

OBJECTIVE

To assess the 6-month outcome and survival of enhanced polyethylene terephthalate (PET) implants as a replacement for the cranial cruciate ligament (CCL) in dogs with spontaneous CCL disease (CCLD).

STUDY DESIGN

Pilot, prospective case series.

ANIMALS

Ten client-owned large breed dogs with unilateral spontaneous CCLD.

METHODS

Dogs were evaluated before and 6 months after intra-articular placement of a PET implant with the Liverpool Osteoarthritis in Dogs questionnaire and force platform gait analysis. Arthroscopy was performed 6 months after surgery to visually assess implant integrity.

RESULTS

Scores on owner questionnaires and limb asymmetry improved in all dogs that reached the 6-month time point, by 51.7% (p = .008) and 86% (p = .002), respectively. The PET implant appeared intact and functioning in two stifles, partially intact and functioning in four stifles and completely torn in three stifles. One dog had an implant infection and was removed from the study. Evidence of deterioration and tearing occurred in the midbody of the implant.

CONCLUSION

Although function improved over the course of this study, only 2/10 implants appeared intact 6 months after placement.

CLINICAL SIGNIFICANCE

Implant survivability prohibits further clinical investigation using this implant.

Intra-articular replacement of a ruptured cranial cruciate ligament using the Mini-TightRope in the dog: a preliminary study

BACKGROUND

The TightRope System is a device developed to provide extracapsular stabilization of the cranial cruciate ligament (CCL) rupture in canine stifles. I was then also employed for the extra-articular treatment of shoulder instability and for the intra-articular treatment of hip luxation in dogs and cats.

OBJECTIVES

To evaluate the feasibility of the Mini-TightRope (mTR) System for the intra-articular treatment of CCL rupture in small breed dogs.

METHODS

A cadaveric canine model was used to record the steps of the surgical procedure. Five client owned dogs weighing from 8 to 10 kg and from 2 to 12 years of age were enrolled in the prospective study in which the mTR device was implanted in the stifle joint to replace the ruptured CCL. The dogs were graded using the Bologna Healing Stifle Injury Index (BHSII) and radiographic osteoarthritis (OA) scores.

RESULTS

The outcomes obtained at the time of the surgery (T0) and for the following 12 months (T12) showed an improvement in the functional parameters (BHSII from a median of 74.3 [range, 58.1-82.4] at T0 to 95.6 [range, 94.1-99.3] at T12]). The OA did not change in 3 dogs and increased by only 1 point in 2 dogs.

CONCLUSIONS

In this preliminary study, the mTR was a successful and repeatable intra-articular surgical procedure for all dogs. Additional studies related to the clinical application of the technique in medium-large dogs should be encouraged.

Joint stability after canine cranial cruciate ligament graft reconstruction varies among femoral fixation sites

OBJECTIVE

To quantify stability in cranial cruciate ligament (CrCL) deficient canine stifles with hamstring grafts affixed at 3 femoral locations.

STUDY DESIGN

Canine stifle motion study using a multi-cohort, repeated measures design.

SAMPLE POPULATION

27 canine cadaver stifles.

METHODS

Hamstring grafts (HG) were affixed at the gracilis-semitendinosus insertion and on the lateral femur (1) proximal trochlear ridge (TR), (2) craniodistal to fabella (F), or (3) condyle center (CC). Total, cranial, and caudal tibial translation and total, medial, and lateral angular displacement, with and without translational load, were quantified with the CrCL intact, transected, and reconstructed. Angular displacement was quantified from points on the distal femur and proximal tibia. Graft strain was calculated from tissue displacement measured at joint angles of 30°, 60°, 90°, and 120°.

RESULTS

Tibial translation was lowest in F constructs, which also achieved the least difference in tibial translation from intact stifles. Tibial translation was lower in intact stifles than in CrCL transected or reconstructed stifles. Less angular displacement of the proximal tibia was detected in the medial than in the lateral direction, and tibial displacement was lower in the cranial than the caudal direction. Angular displacement was lowest in the F treatment group. F constructs had the lowest graft strain at joint angles greater than 30°.

CONCLUSIONS

Femoral fixation of a canine hamstring graft craniodistal to the lateral fabella conferred the best joint stability and lowest graft strain in vitro. No fixation method restored joint stability of the intact CrCL.