Prospective Evaluation of a Citrate-Based Biomaterial Wedge for a Modified Maquet Procedure in the Treatment of Cranial Cruciate Ligament Rupture in Dogs.

OBJECTIVE: The aim of this study was to describe short- and mid-term outcomes, complications, implant bioabsorption and owner satisfaction for a modified Maquet procedure (MMP) in which a novel bioabsorbable citrate-based implant is used as the wedge component to treat cranial cruciate ligament rupture in client-owned dogs. STUDY DESIGN: Prospective clinical study of dogs (n = 13) undergoing MMP (n = 15). Intraoperative complications, postoperative complications, clinical follow-up using a 5-point lameness score and radiographs at 8 weeks and 6 months postoperatively were obtained. Mid-term outcome was assessed via physical examination, radiographs, canine orthopaedic index and owner satisfaction questionnaires. RESULTS: No catastrophic complications occurred. Major complications occurred in 3/15 stifles. All were surgical site infections and one case required implant removal. Minor complications occurred in 9/15 stifles. Non-displaced cortical hinge fractures were the most common minor complication, and these occurred intraoperatively (4/15) or postoperatively (2/15). Three dogs achieved full function, eight dogs acceptable function and the outcome was unacceptable in two dogs. Most owners were satisfied with the procedure (11/13). Complete implant bioabsorption was not confirmed on mid-term radiographs. CONCLUSION: The described MMP with a citrate-based implant can produce satisfactory mid-term results. However, the long-term outcome of this procedure must be evaluated and technical modifications need to be implemented prior to larger-scale use of this implant.

A novel tibial tuberosity advancement technique with cranial implant fixation (TTA CF): a pilot study in sheep.

BACKGROUND: Cranial cruciate ligament rupture is the most frequent orthopedic disorder in human and animals. An array of surgical techniques have been described to stabilize the stifle joint in dogs, including intraarticular stabilization, extraarticular stabilization, and tibial osteotomy techniques. Tibial plateau leveling osteotomy and tibial tuberosity advancement with a lot of modifications are the most common. In this study we report the possibility of fixing the novel titanium implant for tibial tuberosity advancement with two screws in a craniocaudal direction. The aim of our study was to improve the clinical benefit of the tibial tuberosity advancement surgical technique where an attempt was made to reduce the number of screws and obtain a strong implant fixation with minimal bone traumatization. This way of attachment allows to distribute the forces evenly on medial and lateral side of osteotomy gap. RESULTS: Tibial tuberosity advancement with cranial implant fixation was performed in four sheep. Complete radiographic and clinical follow up was recorded. All four sheep had a complete osteotomy line healing at a mean of 10 weeks postoperative (range 8-12 weeks). None of the animals had osteotomy gap healing grades of poor. Minor complication included the minimally cracked Maquet hole on the postoperative radiographs, without displacement of the tibial crest which occurred in 2 sheep. Major complication grade 1, major complication grade 2 and catastrophic were not found. CONCLUSIONS: The novel surgical technique for tibial tuberosity advancement with cranial implant fixation is technically comparable to the recent trend in tuberosity advancement techniques, where partial osteotomy of the cranial tibial tuberosity crest is performed. A cranial implant fixation allows to distribute the forces evenly on medial and lateral side of osteotomy gap, which may result in less number of major complications in dogs. A novel titanium implant decreases the tibial traumatisation by reducing the number of screws.

Use of Synthetic Osteochondral Implants to Treat Bilateral Shoulder Osteochondritis Dissecans in a Dog.

CASE DESCRIPTION: An 8-month-old American Bulldog was presented for assessment of bilateral thoracic limb lameness. Computed tomographic imaging revealed large, deep osteochondritis dissecans lesions in both humeral heads. TREATMENT AND OUTCOME: The osteochondritis dissecans lesions were debrided and the exposed subchondral defects were prepared to receive synthetic grafts. Circular implants consisting of a surface layer of polycarbonate urethane and a deep layer of lattice-type titanium were implanted into the osteochondral defects to reconstruct the articular surface topography. Follow-up clinical examination 1.5, 3 and 9months postoperatively revealed a lack of signs of shoulder pain and resolution of thoracic limb lameness. Nine-month follow-up radiographs showed radiographic evidence of osteointegration of both implants. CLINICAL RELEVANCE: Synthetic osteochondral implantation in the caudocentral aspect of the humeral head appeared technically feasible and effective in resolving lameness caused by humeral head osteochondritis dissecans.

Relationship between Tibial conformation, cage size and advancement achieved in TTA procedure.

BACKGROUND: Previous studies have suggested that there is a theoretical discrepancy between the cage size and the resultant tibial tuberosity advancement, with the cage size consistently providing less tibial tuberosity advancement than predicted. The purpose of this study was to test and quantify this in clinical cases. The hypothesis was that the advancement of the tibial tuberosity as measured by the widening of the proximal tibia at the tibial tuberosity level after a standard TTA, will be less than the cage sized used, with no particular cage size providing a relative smaller or higher under-advancement, and that the conformation of the proximal tibia will have an influence on the amount of advancement achieved. RESULTS: One hundred sixty-four dogs met the inclusion criteria. The mean percentage under-advancement was 15.5%. All dogs had an advancement less than the stated cage size inserted. An association between the proximal tibial tuberosity angle (increased in cases with low patellar tendon insertion), and percentage under-advancement was found, with an increase of 0.45% under-advancement for every 1 degree increase in angle a (p = 0.003). There was also evidence of a difference between the mean percentage under-advancement in breeds (p = 0.001) with the Labrador having the biggest under-advancement. Cage size (p = 0.83) and preoperative tibial plateau angle (p = 0.27) did not affect under-advancement. CONCLUSIONS: The conformation of the tibial tuberosity and therefore the relative cage positioning have an impact on mean percentage under-advancement of the tibial tuberosity after standard TTA. In all evaluated cases, the advancement of the tibial tuberosity was less than intended by the cage size selected.

Animal Models for Evaluation of Bone Implants and Devices: Comparative Bone Structure and Common Model Uses.

Bone implants and devices are a rapidly growing field within biomedical research, and implants have the potential to significantly improve human and animal health. Animal models play a key role in initial product development and are important components of nonclinical data included in applications for regulatory approval. Pathologists are increasingly being asked to evaluate these models at the initial developmental and nonclinical biocompatibility testing stages, and it is important to understand the relative merits and deficiencies of various species when evaluating a new material or device. This article summarizes characteristics of the most commonly used species in studies of bone implant materials, including detailed information about the relevance of a particular model to human bone physiology and pathology. Species reviewed include mice, rats, rabbits, guinea pigs, dogs, sheep, goats, and nonhuman primates. Ultimately, a comprehensive understanding of the benefits and limitations of different model species will aid in rigorously evaluating a novel bone implant material or device.

Ex vivo kinematic studies of a canine unlinked semi-constrained hybrid total elbow arthroplasty system.

OBJECTIVES: Introduction of the Sirius® canine total elbow arthroplasty system, and presentation of the results of a passive range-of-motion analysis based on ex vivo kinematic studies pre-and post-implantation. MATERIALS AND METHODS: Thoracic limbs (n = 4) of medium sized dogs were harvested by forequarter amputation. Plain orthogonal radiographs of each limb were obtained pre- and post-implantation. Limbs were prepared by placement of external fixator pins and Kirschner wires into the humerus and radius. Each limb was secured into a custom-made box frame and retro-reflective markers were placed on the exposed ends of the pins and wires. Each elbow was manually moved through five ranges-of-motion manoeuvres. Data collected included six trials of i) full extension to full flexion and ii) pronation and supination in 90° flexion; a three-dimensional motion capture system was used to collect and analyse the data. The Sirius elbow prosthesis was subsequently implanted and the same measurements were repeated. Data sets were tested for normality. Paired t-tests were used for comparison of pre- and post-implantation motion parameters. RESULTS: Kinematic analysis showed that the range-of-motion (mean and SD) for flexion and extension pre-implantation was 115° ± 6 (range: 25° to 140°). The range-of-motion in the sagittal plane post-implantation was 90° ± 4 (range: 36° to 130°) and this reduction was significant (p = 0.0001). The ranges-of-motion (mean and SD) for supination and pronation at 90° were 50° ± 5, whereas the corresponding mean ranges-of-motion post-implantation were 38° ± 6 (p = 0.0188). CONCLUSION: Compared to a normal elbow, the range-of-motion was reduced. Post-implantation, supination and pronation range-of-motion was significantly reduced at 90° over pre-implantation values. CLINICAL RELEVANCE: These results provide valuable information regarding the effect of the Sirius system on ex vivo kinematics of the normal canine elbow joint. Further, this particular ex vivo model allowed for satisfactory and repeatable kinematic analysis.

Carpal valgus in llamas and alpacas: Retrospective evaluation of patient characteristics, radiographic features and outcomes following surgical treatment.

This study evaluated outcomes of surgical treatment for carpal valgus in New World camelids and correlated successful outcome (absence of carpal valgus determined by a veterinarian) with patient characteristics and radiographic features. Univariable and multivariable analyses of retrospective case data in 19 camelids (33 limbs) treated for carpal valgus between 1987 and 2010 revealed that procedures incorporating a distal radial transphyseal bridge were more likely (P = 0.03) to result in success after a single surgical procedure. A greater degree of angulation (> 19°, P = 0.02) and younger age at surgery (< 4 months, P = 0.03) were associated with unsuccessful outcome. Overall, 74% of limbs straightened, 15% overcorrected, and 11% had persistent valgus following surgical intervention. To straighten, 22% of limbs required multiple procedures, not including implant removal. According to owners, valgus returned following implant removal in 4 limbs that had straightened after surgery.

Valgus carpien chez les lamas et les alpagas : évaluation rétrospective des caractéristiques des patients, des radiographies et des résultats après un traitement chirurgical. Cette étude a évalué les résultats du traitement chirurgical pour le valgus carpien chez des camélidés du nouveau monde et a établi une corrélation entre les résultats fructueux (absence de valgus carpien déterminée par un vétérinaire) et les caractéristiques du patient et des radiographies. Des analyses à variable unique et à variables multiples des données de cas rétrospectifs chez 19 camélidés (33 jambes) traités pour le valgus carpien entre 1987 et 2010 ont révélé que les procédures intégrant un pont radial distal transphyséal présentaient une plus grande probabilité de succès (P = 0,03) après une seule intervention chirurgicale. Une déviation supérieure (> 19°, P = 0,02) et un jeune âge à la chirurgie (< 4 mois, P = 0,03) étaient associés à des échecs. Dans l'ensemble, 74 % des jambes ont été redressés, 15 % ont été corrigées et 11 % présentaient un valgus persistant après l'intervention chirurgicale. Pour le redressement, 22 % des jambes ont nécessité des procédures multiples, ce qui n'incluait pas l'enlèvement de l'implant. Selon les propriétaires, le valgus est réapparu après l'enlèvement de l'implant dans 4 jambes qui avaient été redressées après la chirurgie.(Traduit par Isabelle Vallières).

[First clinical experiences with a new cementless knee endoprosthesis for the dog]. / Erste klinische Erfahrungen mit einer neuen zementlosen Knie-Endoprothese für den Hund.

OBJECTIVE: This paper reports on the clinical application and first experiences of a newly developed cementless knee endoprosthesis for dogs. MATERIAL AND METHODS: The GenuSys knee-endoprosthesis was implanted in 23 knees of 22 dogs with severe gonarthritis and a history of pain. Their body weight ranged from 28 to 55 kg, their age between 5 and 12 years. This knee implant for dogs is a cementless "mobile bearing prosthesis". An additional fixation with one screw is necessary in the femoral component. Currently, there are four standard sizes of the prosthesis available. RESULTS: At the end of the study, 16 of 22 controlled patients (72.7%) were fully weightbearing on the operated limb or only showed a discreet lameness. We observed no complications in 12 cases (54.5%). In 10 cases problems in the course of healing were detected and made or would have made reoperation necessary. The complications noted were subluxation (n = 6, 27.3%), wound infection (n = 3, 13.6%) and a serious decrease in the range of motion (n = 1, 4.5%). Four of these 10 patients (40%) were subsequently healed through surgery. The remaining six dogs (27.3%) were euthanized or underwent arthrodesis of the leg. CONCLUSION AND CLINICAL RELEVANCE: Sixteen of 22 dogs (72.2%) showed much better weightbearing and an increased quality of life after endoprosthesis of the knee. Although the complication rate was high, we expect better results in the future due to improvements in the equipment and surgical procedure. A definitive conclusion can only be made based on the results of a long-term study.

Mechanical properties of isolated loops of nylon leader material, polyethylene cord, and polyethylene tape and mechanical properties of those materials secured to cadaveric canine femurs via lateral femoral fabellae, toggles placed through bone tunnels, or bone anchors.

OBJECTIVE: To determine mechanical properties of various prosthetic materials secured to cadaveric canine femurs via various methods and to compare results with those for isolated loops of prosthetic material. SAMPLE: 80 femurs obtained from cadavers of skeletally mature large-breed dogs. PROCEDURES: 10 femoral constructs in each of 8 groups (single circumfabellar loop of polyethylene cord, double loop of polyethylene tape secured via a bone anchor [BAPT], single or double circumfabellar loops of nylon leader material [CNL] or polyethylene tape [CPT], or single or double loops of polyethylene tape secured via a toggle placed through a bone tunnel [BTPT]) and 10 isolated loops of prosthetic material in each corresponding configuration were tested. Stress relaxation, creep, elongation, load at 3 mm of displacement, stiffness, and peak load at failure were determined. RESULTS: 5 single CNL constructs failed before completion of testing. Double CNL and single circumfabellar polyethylene cord constructs had the lowest loads at 3 mm of displacement. Single and double CPT constructs had the highest stiffness. Double BTPT and CPT constructs had the highest peak loads at failure. Double BTPT, double CPT, and BAPT constructs were mechanically superior on the basis of lower creep and stress relaxation and higher stiffness and load at 3 mm of displacement versus other constructs. Stiffness of femoral constructs was 28% to 69% that of corresponding isolated prosthetic loops. CONCLUSIONS AND CLINICAL RELEVANCE: Double BTPT, double CPT, and BAPT constructs were mechanically superior to other constucts. Mechanical properties and methods of anchorage and securing of free ends of prostheses contributed to mechanical properties of constructs.

The effects of extra-articular suture tension on contact mechanics of the lateral compartment of cadaveric stifles treated with the TightRope CCL or lateral suture technique.

OBJECTIVE: To determine the effect of suture tension on contact pressures in the lateral compartment of the stifle for the TightRope CCL((R)) (TR) and circumfabellar-tibial suture (LS) techniques. STUDY DESIGN: Ex vivo biomechanical study. SAMPLE POPULATION: Pelvic limbs (n=12) from dogs weighing 21-24 kg. METHODS: A pressure sensor was used to record peak contact pressure (PCP) and mean contact pressure (MCP) and contact area (CA) in limbs mounted in a materials testing machine. Stifles were stabilized using either a TR or LS technique and the prosthesis was tensioned increasingly from 25 to 70 N. PCP, MCP, and CA were collected at each applied tension before and after applying an axial load of 150 N. RESULTS: In the unloaded condition, LS stabilization resulted in a significant increase (P=.034) in PCP at >or=40 N tensions, whereas TR stabilization resulted in a significant increase (P=.047) in PCP at 70 N tension. There was a significant increase in CA at tensions >or=60 N in the LS group. No effect on MCP was noted. No significant differences in contact pressures were observed in the loaded condition. There were no significant differences in normalized PCP and CA between stabilization groups at any of the tension increment. CONCLUSIONS: The application of high tension to the extra-articular prosthesis alters lateral compartment contact pressures in the unloaded stifle in this ex vivo model. CLINICAL RELEVANCE: Over tightening of an extra-articular prosthesis may increase lateral compartment pressure at the time of surgery. The clinical implications of this finding are unknown, as weight bearing may negate any detrimental effect of high prosthesis tension.

Revision of an unstable HELICA endoprosthesis with a Zurich cementless total hip replacement.

A six-year-old, female, spayed Labrador Retriever was evaluated for progressive lameness of one year duration, ending in non-weight-bearing of the right hindlimb. The dog had a history of severe coxarthrosis of both hip joints, and had a HELICA hip prosthesis implanted in the right hip 18 months before. On survey radiographs, the acetabular and femoral components appeared unstable, with a large void in the proximal femur and a lacy periosteal reaction on the trochanter. Arthrocentesis was performed to rule out septic loosening. As culture samples were negative, the dog underwent surgery. We report the successful revision of an unstable HELICA screw hip prosthesis with a Zurich cementless total hip replacement. The patient had a good clinical and radiological outcome seven months postoperatively.

Nonconstrained elbow replacement in dogs.

OBJECTIVE: To review development of a nonconstrained total elbow replacement system for use in dogs and report the surgical technique used for implantation. STUDY DESIGN: Descriptive report. ANIMALS: Dogs with chronic elbow osteoarthritis (OA) unresponsive to medical management for at least 1 year. METHODS: A nonconstrained elbow replacement system (radioulnar and humeral components) was developed and used in dogs with medically nonresponsive elbow OA. The components were refined based on evaluation of clinical outcome. Changes in humeral stem design for composite fixation, the contours of the articulating surfaces, and in the humeral component to increase range of motion were incorporated. Drilling and cutting guides were developed to facilitate accuracy of implantation. RESULTS: With component refinement, more favorable long-term functional outcome was achieved. CONCLUSIONS: Design improvements incorporated into the elbow replacement system should increase treatment success. CLINICAL RELEVANCE: Total elbow replacement in dogs is possible and good long-term outcome can be achieved.

The use of veterinary cuttable plates for carpal and tarsal arthrodesis in small dogs and cats.

The objective of the study was to evaluate, retrospectively, carpal and tarsal arthrodesis in small dogs and cats by using veterinary cuttable plates in 6 animals and comparing those with arthrodesis stabilized with other implants in 9 animals. Veterinary cuttable plates were used for 1 pancarpal, 2 partial tarsal, and 3 pantarsal arthrodeses. Other implants were used to stabilize 1 pancarpal, 6 partial tarsal, and 2 pantarsal arthrodeses. In the veterinary cuttable plates group, complications included 2 cases with pressure sores and 1 case with screw loosening. One animal was lost to follow-up and 4 of the remaining 5 were always weight-bearing. In the other group, there were 2 cases with pressure sores, 1 case with dermatitis, and 2 cases with pin migration. Six out of 9 animals were always weight-bearing. The use of veterinary cuttable plates appears to be a suitable option with a good clinical outcome.

Radiologic, mechanical, and histologic evaluation of 2 glenoid prosthesis designs in a canine model.

Aseptic loosening of glenoid components is a common problem associated with total shoulder arthroplasty. A new glenoid design aimed at improving fixation outcomes was compared with conventional keeled glenoids in weight-bearing canine shoulders. Radiographic, histologic, and mechanical tests were performed at 3 postoperative intervals (0, 3, and 6 months). The uncemented pegged glenoid achieved bone ingrowth around the peg flanges in each case. This result was confirmed histologically and radiographically. Mechanical results indicated that mean fixation strength increases significantly between 0 and 3 months after surgery and remains strong through 6 months. In contrast, conventional keeled glenoids were found to have partial or complete radiolucent lines around the keel in each instance, and mechanical testing demonstrated that mean fixation strength weakens significantly between 0 and 3 months after surgery and remains weak through 6 months. These results show that stem design changes can improve implant fixation. A cementless fluted peg stem was superior to a conventional cemented keel design in achieving osseous integration and fixation in a weight-bearing animal model.

Biomechanical properties of braided polyester tapes intended for use as intra-articular cranial cruciate ligament prostheses in dogs.

OBJECTIVE: To determine the in vitro structural and material properties of braided, multifilament, nonabsorbable polyester tapes, used for intra-articular stabilization of cranial cruciate ligament- (CCL-) deficient stifle joints in dogs, and compare those with properties of multifilament polyamide tapes. SAMPLE POPULATION: 30 polyester tapes (width, 4 mm), 10 polyester tapes (width, 7 mm), and 30 polyamide tapes (width, 4 mm) were tested to failure. Cyclic loading experiments were also performed, using 3 polyester tapes of each width. PROCEDURE: Tapes were mounted in a tensile tester as single loops, simulating intra-operative conditions, and elongated to failure at 1,000 mm/min. Additionally, the behavior of polyester tapes was tested at different elongation rates. In a second series of experiments, biomechanical variables of the polyester tapes were measured after 25 sets of 2,000 cycles between physiologic force limits. RESULTS: Mean (+/- SD) ultimate loads of the 4-mm wide polyamide tapes, 4-mm wide polyester tapes, and 7-mm wide polyester tapes were 266.48 +/- 13.19 301.78 +/- 16.92, and 726.40 +/- 37.74 N, respectively. Corresponding stiffnesses were 15.57 +/- 0.49, 21.63 +/- 2.19, and 34.85 +/- 2.66 N/mm, respectively. Failure properties of polyester tapes were affected by previous cyclic loading. CONCLUSIONS AND CLINICAL RELEVANCE: Polyester tapes of 4- or 7-mm widths should be able to resist forces resulting from weight bearing in dogs, suggesting that these tapes will be effective for stabilization of the stifle joint in dogs with a ruptured CCL.

Collateral ligament prosthesis for the repair of subluxation of the metatarsophalangeal joint in a jersey cow.

A two-and-a-half-year-old Jersey cow had been moderately lame in its right hindlimb for one month. Clinical and radiographic examinations revealed an incomplete lateral luxation of the metatarsophalangeal joint. The medial condyle of the metatarsal bone was locked in the condylar groove of the medial first phalanx. The subluxation was reduced, the joint carefully debrided and irrigated, and the torn ligament was replaced with a synthetic prosthesis which was fixed with titanium alloy staples. One year after surgery, the joint was slightly swollen but the cow was not lame.

Surgical treatment of osteoarthritis.

Surgical treatment of OA is appropriate when conservative therapy fails or is inadequate. The veterinary orthopedist's goals in treatment should be to alleviate pain, maintain function, and prevent or remove the potential for further degeneration of the joint. Currently, in veterinary surgery, THR and femoral head and neck excision are the primary treatments for OA of the coxofemoral joint. Other joints are treated primarily by arthrodesis or excision arthroplasty. Arthroscopy is proving to be a valuable tool in the diagnosis and treatment of OA, and total stifle and elbow replacement and cartilage resurfacing through chondrocyte grafting are on the horizon as potential treatment options.

Total replacement of the metatarsophalangeal joint in the horse. A single pilot study.

In this paper the successful replacement of an equine metatarsophalangeal joint by a human total condylar knee prosthesis is reported. In the period of observation following implantation of the endoprosthesis the experimental animal showed almost no lameness when exercised at walk, bearing weight on the operated limb. Flexion and extension of the joint were markedly reduced. The clinical and histological observations clearly support further investigation into the equine metatarsophalangeal joint replacement by an endoprosthesis.