Mapping Subchondral Bone Density of Selected Donor and Recipient Sites for Autologous Osteochondral Transplantation in the Canine Stifle Joint Using Computed Tomographic Osteoabsorptiometry

Preliminary evaluation of an osteochondral autograft, a prosthetic implant, and a biphasic absorbable implant for osteochondral reconstruction in a sheep model

OBJECTIVE

To determine the ability of three implants to enhance the healing of osteochondral defects: (1) a biphasic construct composed of calcium phosphate (CaP) and chitosan/cellulosic polymer, (2) a titanium-polyurethane implant, and (3) an osteochondral autograft.

STUDY DESIGN

Experimental study.

ANIMALS

Ten adult female sheep.

METHODS

In five sheep, an 8-mm diameter osteochondral defect was created on the medial femoral condyle of a stifle and filled with a synthetic titanium-polyurethane implant. In five sheep, a similar defect was filled with an osteochondral autograft, and the donor site was filled with a biphasic construct combining CaP granules and a chitosan/cellulosic polymer. Sheep were monitored daily for lameness. Stifle radiographs and MRI were evaluated at 20 weeks, prior to animals being humanely killed. Surgical sites were evaluated with histology, microcomputed tomography, and scanning electron microscopy.

RESULTS

Clinical outcomes were satisfactory regardless of the tested biomaterials. All implants appeared in place on imaging studies. Osteointegration of prosthetic implants varied between sites, with limited ingrowth of new bone into the titanium structure. Autografts and biphasic constructs were consistently well integrated in subchondral bone. All autografts except one contained a cartilage surface, and all biphasic constructs except one partially restored hyaline cartilage surface.

CONCLUSION

Biphasic constructs supported hyaline cartilage and subchondral bone regeneration, although restoration of the articular cartilage was incomplete.

CLINICAL IMPACT

Biphasic constructs may provide an alternative treatment for osteochondral defects, offering a less invasive approach compared with autologous grafts and eliminating the requirement for a prosthetic implant.

Synthetic osteochondral resurfacing for treatment of large caudocentral osteochondritis dissecans lesions of the humeral head in 24 dogs

OBJECTIVE

To report the outcome of dogs with large, caudocentral, osteochondritis dissecans (OCD) lesions of the humeral head treated with synthetic osteochondral resurfacing (SOR) implants.

STUDY DESIGN

Retrospective case series.

ANIMALS

Twenty-four client-owned large breed or giant dogs.

METHODS

The medical records of all dogs treated with first generation (G1) and second generation (G2) SOR implants were reviewed. All dogs were assessed with clinical examination and imaging 12 weeks after surgery. Assessment of outcome was based on subjective assessment of lameness, scoring of postoperative radiographs, and the Liverpool Osteoarthritis in Dogs (LOAD) questionnaire.

RESULTS

Osteochondral resurfacing was performed with a G1 implant in 13 dogs (15 shoulders) and a G2 implant in 11 dogs (13 shoulders). Lameness resolved in all dogs treated with G1 implants and in 10 dogs treated with G2 implants by 12 weeks after surgery. One dog treated with a G2 implant was found to have an implant-associated infection, requiring implant removal. No recurrence of lameness was reported in 9 limbs treated with G1 implants and 10 limbs treated with G2 implants that were available for clinical review at a median time of 387 and 365 days, respectively, after surgery. Mean postoperative LOAD scores were 4.2 of 52 and 5.2 of 52 in dogs treated with a G1 or a G2 implant, respectively.

CONCLUSION

Synthetic resurfacing was technically feasible in all joints of this study and resulted in good clinical results.

CLINICAL SIGNIFICANCE

The use of SOR implants seems viable to treat large caudocentral OCD lesions of the humeral head in dogs and warrants prospective comparison with conventional arthroscopic treatment.

Long-term effects of tibial plateau leveling osteotomy and tibial tuberosity advancement on tibial plateau subchondral bone density in dogs

OBJECTIVE

To evaluate long-term loading patterns using subchondral bone density (SBD) distribution of the tibial plateau after tibial plateau leveling osteotomy (TPLO) and tibial tuberosity advancement (TTA).

STUDY DESIGN

Cross-sectional study.

ANIMALS

Adult (> 2 years), medium to large breed dogs (>20 kg) that had been treated with TPLO or TTA at least 1 year prior to the study were recruited. A normal cohort of similar age and weight dogs with normal physical and orthopedic examinations served as control.

METHODS

Dogs were sedated for computed tomography (CT) of the stifle, and DICOM (digital imaging and communications in medicine) files were processed for CT osteoabsorptiometry (CTOAM). Tibial plateaus were sampled at 6 zones, and CTOAM was used to determine regional and maximal areas of SBD as a marker of joint loading.

RESULTS

Data were collected on 48 stifles in 31 dogs (15 TPLO, 11 TTA, 22 control). Lower Hounsfield unit (HU) values were measured in the caudal and mid-region of the lateral tibial plateau after TPLO and compared to normal. HU values did not differ between joints treated with TTA and those in the control group.

CONCLUSION

TPLO may alter stifle load distribution relative to the normal control group. There were no differences between TTA and the control group.

CLINICAL SIGNIFICANCE/IMPACT

Despite ongoing osteoarthritis (OA) in dogs after surgical intervention for cranial cruciate disease, changes in tibial SBD are minor and may not correlate with clinical function.

Subchondral bone density distribution of the talus in clinically normal Labrador Retrievers

BACKGROUND

Bones continually adapt their morphology to their load bearing function. At the level of the subchondral bone, the density distribution is highly correlated with the loading distribution of the joint. Therefore, subchondral bone density distribution can be used to study joint biomechanics non-invasively. In addition physiological and pathological joint loading is an important aspect of orthopaedic disease, and research focusing on joint biomechanics will benefit veterinary orthopaedics. This study was conducted to evaluate density distribution in the subchondral bone of the canine talus, as a parameter reflecting the long-term joint loading in the tarsocrural joint.

RESULTS

Two main density maxima were found, one proximally on the medial trochlear ridge and one distally on the lateral trochlear ridge. All joints showed very similar density distribution patterns and no significant differences were found in the localisation of the density maxima between left and right limbs and between dogs.

CONCLUSIONS

Based on the density distribution the lateral trochlear ridge is most likely subjected to highest loads within the tarsocrural joint. The joint loading distribution is very similar between dogs of the same breed. In addition, the joint loading distribution supports previous suggestions of the important role of biomechanics in the development of OC lesions in the tarsus. Important benefits of computed tomographic osteoabsorptiometry (CTOAM), i.e. the possibility of in vivo imaging and temporal evaluation, make this technique a valuable addition to the field of veterinary orthopaedic research.

Osteochondral autograft transfer for treatment of osteochondritis dissecans of the caudocentral humeral head in dogs

OBJECTIVE

To establish whether osteochondral autograft transfer (OAT) procedures for osteochondritis dissecans (OCD) of the canine caudocentral humeral head would restore articular contour, resurface osteochondral defects, and resolve lameness in dogs with OCD.

STUDY DESIGN

Case series.

ANIMALS

Dogs (n=14) with caudocentral humeral head OCD (16 shoulders).

METHODS

After arthroscopic assessment, the humeral head was exposed by arthrotomy. The OCD lesion was debrided and OATS(™) instrumentation used for resurfacing the defect with osteochondral core grafts collected from the stifle. Recipient sockets were created to maximally resurface articular lesions. Outcomes measures included clinical, radiographic, and arthroscopic examination at 12-18 weeks and clinical examination at 12-46 months (mean, 30.8 months) postoperatively.

RESULTS

Resurfacing of the humeral head was achieved in all dogs. Subjectively, lameness resolved in 9 of 16 limbs by 5-6 weeks postoperatively, and in 13 limbs by 12-18 weeks. Radiographically, all autografts were maintained. On second-look arthroscopy, the grafted section was intact, resilient on probing, satisfactorily conformed to the adjacent articular contour, and grossly appeared consistent with hyaline or fibrocartilage depending on the graft source. Of 12 limbs available for 12-46 months reevaluation, none were considered lame and mild discomfort on shoulder manipulation was recorded for only 1 joint.

CONCLUSIONS

OAT procedures are technically feasible in the caudocentral aspect of the canine humeral head. Articular contour reconstruction, resurfacing of osteochondral defects, and amelioration or resolution of short-term lameness may be achieved.