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Objective The aim of this study was to describe a new surgical method of segmental femoral ostectomy for the reconstruction of the femoropatellar joint (FPJ) in dogs with medial patellar luxation (MPL) grade IV. Study Design The medical records of six dogs that underwent segmental femoral ostectomy to reconstruct the FPJ for MPL grade IV were retrospectively reviewed. The data included breed, age, body weight, comorbidities, history of orthopaedic abnormalities, pre- and postoperative radiographic findings, morphological indicators measured on three-dimensional computed tomographic multiplanar reconstruction images, surgical methods and postoperative complications. Outcomes Eleven hindlimbs with MPL grade IV in six dogs underwent segmental femoral ostectomy to reconstruct the FPJ with the four basic surgical procedures. Six stifle joints with femoral varus deformity were treated by closing wedge ostectomy and segmental ostectomy, while five stifle joints were treated by segmental ostectomy alone. The mean resected femoral length was 11.7 mm. The mean resected femoral length relative to the preoperative femoral length was 14.3%. The stability and congruity of the FPJ was markedly improved, with an increased range of motion in all dogs compared with their preoperative status. Conclusion Segmental femoral ostectomy was a useful treatment method for MPL grade IV with shortened quadriceps muscle length relative to the femoral length. Reconstruction of the FPJ is important for recovery of limb function.

Objective The aim of this study was to report the use of custom saw guides produced using computed tomographic imaging (CT), computer simulation and three-dimensional (3D) printing to aid surgical correction of antebrachial deformities in six dogs. Materials and Methods Antebrachial limb deformities in four small, and two large, breed dogs (seven limbs) were surgically corrected by a radial closing wedge ostectomy and ulnar osteotomy. The location and orientation of the wedge ostectomy were determined using CT data, computer-assisted planning and production of a saw guide in plastic using a 3D printer. At surgery, the guide was clamped to the surface of the radius and used to direct the oscillating saw blade. The resultant ostectomy was closed and stabilized with a bone plate. Results Five limbs healed without complications. One limb was re-operated due to a poorly resolved rotational component of the deformity. One limb required additional stabilisation with external fixation due to screw loosening. The owners of five dogs completed a Canine Orthopedic Index survey at a follow-up period of 37 to 81 months. The median preoperative score was 3.5 and the median postoperative score was 1, representing an overall positive effect of surgery. Radiographically, 5/7 limbs were corrected in the frontal plane (2/7 were under-corrected). Similarly, 5/7 limbs were corrected in the sagittal plane, and 2/7 were over-corrected in the sagittal place. Conclusions Computer-aided design and rapid prototyping technologies can be used to create saw guides to simplify one-stage corrective osteotomies of the antebrachium using internal fixation in dogs. Despite the encouraging results, accurate correction of rotational deformity was problematic and this aspect requires further development.

Objectives The aim of this study was to report the complication of lateral radial head subluxation following proximal ulnar osteotomy (PUOO) or proximal ulnar ostectomy (PUOE) in eight dogs. Materials and Methods Case records and diagnostic imaging of dogs developing lateral radial head subluxation following PUOO (n = 7) or PUOE (n = 2) were retrospectively reviewed. Information pertaining to clinical history, signalment, presenting condition, lameness grade, diagnostic imaging and initial surgery details, postoperative complications and their management were retrieved. Outcomes were established from subsequent clinical histories or telephone interviews with referring veterinarians. Comparison was made to a single-centre cohort without lateral radial head subluxation following PUOO or PUOE. Results Eight dogs (median age: 9.5 months [range: 6 months–6 years], median weight 7.7 kg [range: 5–28 kg]) were included. Six dogs had a PUOO performed; five dogs had unilateral surgery and one had bilateral surgery. Two dogs had unilateral PUOE surgery. Median time to diagnosis of lateral radial head subluxation following surgery was 6.5 weeks (range: 2–20 weeks). Five of the eight dogs had surgical revision of lateral radial head subluxation. Resolution of lateral radial head subluxation was achieved in four dogs, with three achieving acceptable to good mobility. One dog had poor postoperative mobility. A fifth dog remained lame after revision surgery failure. Three dogs did not have revision surgery; two underwent limb amputation and one dog remained lame as revision surgery was declined. Clinical Significance Lateral radial head subluxation is a potentially severe postoperative complication following PUOO or PUOE.

SummaryObjective: To describe a cohort of dogs with medial patellar luxation managed with a distal femoral lateral closing wedge ostectomy (DFO) as a component of comprehensive treatment, and to report radiographic and long-term clinical outcome of this technique.Methods: Medical records of dogs that had a lateral closing wedge DFO as part of management of medial patellar luxation at three veterinary teaching hospitals were reviewed. Surgical reports as well as the preoperative, postoperative, and follow-up radiographs were reviewed. The anatomical lateral distal femoral angle (aLDFA) was determined. Long-term clinical outcome was assessed by telephone interview with the owner.Results: A lateral closing wedge DFO was performed on 66 limbs. The mean pre- and postoperative aLDFA was 107.6° ± 5.8° and 94.1° ± 4.2°, respectively. Cranial cruciate ligament disease was identified in 28/66 affected limbs. Tibial angular deformity, torsional deformity, or both was identified in nine of the 66 limbs. Ostectomy healing was confirmed radiographically in 51/66 limbs. The mean time to union was 73 ± 37 days. All patellae were in the normal position and stable. Complications included infection (2/51), fixation failure (1/51), delayed healing (2/51), and persistent lameness (1/51).Clinical significance: In this cohort of cases, DFO was a highly successful and repeatable component of surgical treatment for dogs with medial patellar luxation associated with femoral varus. This study also provides more evidence of the high rate of concurrent cranial cruciate ligament disease in cases of medial patellar luxation complicated by fe-moral varus, and supports an association between stifle instability and medial patellar luxation.

SummaryObjectives: To compare the bending and torsional mechanical properties of mono- and bicortical locking screws in a canine cadaveric tibial gap ostectomy bridged by a locking compression plate (LCP).Methods: A 10-hole 3.5 mm LCP was applied medially to the tibia with a gap ostectomy using locking screws in the two proximal and distal plate holes. One tibia of each pair was randomly assigned monocortical screws and the other bicortical screws. Constructs were tested non-destructively in mediolateral and caudocranial four-point bending and torsion, and then to failure in four-point bending. Stiffness, yield and failure variables were compared between screw lengths and load conditions using analysis of variance.Results: Caudocranial and mediolateral fourpoint bending stiffnesses were not different between screw constructs. Torsional stiffness was greater and neutral zone smaller for bicortical constructs. Constructs were stiffer and stronger in caudocranial bending than in mediolateral bending. In caudocranial bending, bicortical constructs failed by bone fracture and monocortical constructs by screw loosening.Conclusion: Bicortical constructs were stiffer than monocortical constructs in torsion but not bending. Bicortical screw constructs failed by bone fracture under the applied loads whereas monocortical screw constructs failed at the bone-screw interface.Clinical relevance: Bicortical screw placement may be a safer clinical alternative than monocortical screw placement for minimally invasive percutaneous osteosynthesis LCPplated canine tibiae with comminuted diaphyseal fractures.

SummaryObjective: To compare the in vitro biomechanical performance of two String-of-Pearls (SOP) plate constructs in a canine distal humeral metaphyseal gap model.Methods: Seven pairs of canine cadaveric humeri, including the elbow joints, were prepared. One group consisted of a unilateral medially placed SOP plate with bicortical screws (UNI). The second group consisted of bilateral caudo-medial and caudo-lateral SOP plates applied with monocortical screws (BI). A 2 cm ostectomy was performed immediately proximal to the supratrochlear foramen. Constructs were tested in torsion and axial compression.Results: The UNI constructs had significantly lower stiffness in torsion and axial compression than the BI group. However, UNI constructs had a significantly higher ultimate strength than BI constructs. All UNI constructs failed by bending of the transcondylar screw and SOP plate. All BI constructs failed by axial pullout of the distal most screws.Clinical significance: In stabilizing canine supracondylar humeral fractures as modeled here, both the UNI model and the BI model demonstrated biomechanical advantages. The incorporation of a transcondylar screw through the medial plate appears to be beneficial to construct strength.

SummaryCementless total hip implants are relatively new to the veterinary market and therefore complication rates and prognostic indicators associated with the procedure have not been thoroughly documented. The objective of this study was to determine the prevalence of complications and identify prognostic indicators of success or failure for the Zurich cementless total hip replacement (THR). Medical records of 163 dogs that underwent Zurich cementless-THR were reviewed continuous and categorical variables, clinical outcomes and complications were recorded. Complications were separated into intra-operative (IOC), short-term (STC), and long-term (LTC). Bivariate and multivariate statistical analysis was used to compare complications. The clini-cal significance of this study was to provide surgeons with prognostic indicators of success or failure when evaluating prospective Zurich cementless-THR patients, and to report the complication rate of Zurich cementlessTHR. The complication rates of Zurich cementless-THR were then compared to previously-reported complication rates of cemented-THR and other cementless-THR systems. Short-term complications, LTC, and IOC rates of Zurich cementless-THR were found to be 6.75%, 10.4%, and 11.0% respectively. The most common complications were intra-operative femoral fracture, luxation of the implant, and septic loosening of the implant. Increased body weight and prior cemented-THR or fe-moral head and neck ostectomy of the contra-lateral hip were identified as negative prognostic indicators. The overall complication rate identified was greater than those previously reported for other cementless- and cemented-THR systems.

Summary Objective: This case report describes the novel use of an intramedullary pin in an eight-month-old cat to repair malunion of a right transverse ilial fracture that was causing pelvic canal diameter narrowing and constipation. Method: A routine, right femoral head and neck ostectomy was performed due to the presence of a femoral head fracture with apparent femoral neck necrosis. Significant callus formation around the ilial fracture was removed in order to achieve satisfactory fracture reduction. A 2 mm Steinmann pin was passed in a retrograde fashion from the acetabular fracture towards the ischial tuberosity, and following removal of the trochar tip and reduction of the fracture, was driven normo-grade to end in the cranial ilial wing. The pin was bent at the ischium following cutting in an attempt to prevent cranial migration. Results: Radiographic examination showed good fracture alignment and increased pelvic diameter by 31% The cat regained normal limb function and the constipation resolved. Clinical significance: A transilial pin was utilised successfully in a cat to realign and stabilise a simple transverse ilial fracture following femoral head and neck ostectomy. This technique has the potential to be useful for stabilisation of feline caudal ilial body fractures, but should not be used where there is articular surface involvement unless the coxofemoral joint is not preserved. Further studies are required to assess this technique.

SummaryA 2-year-old, female, neutered Newfoundland presented with pelvic limb lameness due to a distal tibial valgus deformity. A left distal fibula ostectomy and disto-medial tibial cuneiform ostectomy were performed with reduction and stabilisation using plate-rod internal fixation. Following surgical correction of the deformity the dog regained good functional mobility of the limb.

SummaryThe study purposed to elaborate a model of non-union to test a new biomaterial enhancing bone healing in large segmental defects. The authors’ concern was to develop a model of osteosynthesis capable of maintaining the stability of a femur that sustained a segmental defect. Also, they intended to determine the length of a defect that would create a nonunion. The madel was a 20-mm segmental bone defect coupled with an appropriate osteosynthesis in the rabbit femur. Two groups of rabbits underwent a mid-shaft ostectomy. Osteosynthesis was mode by two superposed holes 2-mm cuttable plates with cerclage wires. In one group, an additional intramedullary pin was inserted. The experiment lasted 16 weeks. The rabbits of the control group suffered fracture of the plates before the end of the experiment. The rabbits of the test group showed stability of the implants and nonunion of the defect. It was concluded that a mid-shaft segmental defect of 20 mm, coupled with an osteosynthesis combining plates, wires and intramedullary pin, is a valid critical size defect model in the rabbit femur.

SummaryIn a prospective trial over seven years (1993-1999), 44 joints from 41 dogs with an ununited anconeal process are reported. The average age of the animals was 23 weeks. With regard to breed distribution, the German Shepherd was most frequently represented with 29 animals.In 35 joints, the anconeal process was stabilised with lag screw and pin, as there was no fibrous connection between the anconeal process and the ulna. Additionally, in all cases an ulna ostectomy was performed. In nine joints, the connection of the anconeal process to the olecranon was firm and only a proximal ulna ostectomy was performed. The patients were rechecked clinically and radiologically, at an average of 13 weeks post operation. With one exception, in all of the cases the apophysis was closed. The implants were removed in 25 patients. The surgical results were examined once more after an average of 20 months in 43 joints (40 dogs). 83.7% of the cases (n = 36) did not show any lameness after the combined therapy with fixation of the isolated anconeal process and osteotomy of the ulna (n = 28) or ulna ostectomy only (n = 8) and were assessed as ‘good’. Six dogs (five with fixation, one with ostectomy) showed some degree of lameness after heavy strain and were only evaluated as ‘satisfactory’. One dog still had a striking low to medium grade lameness, so that the result was regarded as ‘unsatisfactory’. With regard to the development of arthrosis, only nine of the 30 joints (30%) examined radiographically showed a mild increase of the arthroses during later examinations.In many cases excision of the ununited anconeal process leads to unsatisfactory long-term results. Frequently surgical treatment does not lead to fusion. This paper describes a concept for treatment of an ununited anconeal process and the short- and long-term results. Proximal ostectomy of the ulna was performed, as a single measure, when the anconeal process was tightly in place. In joints with a loose anconeal process, the piece of bone was stabilised with implants, in addition to an ostectomy of the ulna. After an average of three months, the anconeal process had fused with the ulna, in all hut one case. In long-term follow-ups, after an average of 20 months, most of the dogs did not show any lameness, even after exercise. In only a few joints was a minor increase of arthrosis noted. The technique described is considered to be useful to treat the ununited anconeal process in young dogs.

SummaryRectus femoris muscle slings were transposed over femoral head ostectomy sites in four large breed dogs, while in three other dogs, standard femoral head and neck excision arthroplasty was performed. After the operation two dogs, with rectus femoris muscle slings, showed transient swelling of the operated limb and remained weight bearing minimally throughout the 28-day study period. In the two remaining dogs with muscle transposition, the surgical sites were normal, but decreased weight bearing and marked lameness were apparent. The dogs with standard femoral head excisions did not have any postoperative problems with the surgical sites and were weight bearing, with slight to moderate gait abnormalities, after the operation. All of the dogs showed decreases in coxofemoral range of motion, standing hip angle and limb length of the operated leg but postoperative differences between the two treatment groups were not significant. Thigh muscle circumference was significantly less in dogs with rectus femoris muscle slings than those with standard femoral head excision. Extensive perfusion of transposed slings was apparent on angiographic studies. Histopathology of muscle slings showed focal inflammation, muscle fibre atrophy and fibrosis with intact neurovascular supply.Femoral head excisional arthroplasty was performed in seven large breed dogs, four of which had adjunctive rectus femoris muscle slings trans-posed over ostectomy sites. Although the rectus femoris muscle sling remained vascular and was associated with minimal immediate postoperative complications, dogs with muscle transposition showed decreased weight bearing, more obvious lameness and a slower return to function, than dogs with standard femoral head and neck excision. Dogs with rectus femoris muscle slings did not show any improvement in coxofemoral range of motion, standing hip angle or limb length, rather more thigh muscle atrophy was evident on day 28 after surgery.

SummaryTo reduce postoperative complications due to pelvic canal narrowing following triple pelvic osteotomy, it is important to minimize the length of the pubic remnant on the acetabular segment. Three different techniques for performing the pubic osteotomy were compared: a lateral wire saw technique, a lateral osteotome technique and a ventral osteotome ostectomy technique. The lateral wire saw and ventral ostectomy techniques resulted in significantly shorter pubic remnants than the lateral osteotome technique. The osteotomies performed with the wire saw were more accurate and precise than those performed with the osteotome. The lateral wire saw technique is a practical alternative to the ventral ostectomy technique for performing the pubic osteotomy.A comparison of three different pubic osteotomy techniques for the triple pelvic osteotomy showed that minimal pubic remnants can be achieved with either the lateral wire saw or ventral ostectomy technique. Osteotomies made by the wire saw were more accurate and precise than those made by the osteotome.

SummaryTwenty-four dogs (27 limbs) were evaluated after surgery for correction of forelimb angular limb deformities. Partial ulnar ostectomies or definitive corrective osteotomies were performed depending upon the age of the dog. According to owner assessment nine of fourteen limbs were considered functionally good, or excellent, after partial ulnar ostectomies. Younger dogs appeared to have better functional results after dynamic correction with the mean age at surgery of dogs with good to excellent results being 6.5 months contrasted to the mean age at surgery of dogs with fair to poor results being 9.75 months. Ten of fourteen limbs were considered functionally good or excellent after definitive corrective osteotomy. One dog had definitive osteotomy after partial ulnar ostectomy in order to further correct a residual angular deformity. However, 58% of the limbs with radiographic follow-up had signs of degenerative joint disease (DJD). There were not significant differences between neither degree of angulation remaining after surgery and the functional result nor the degree of angulation remaining after surgery and the development of DJD. A prospective study is warranted to more objectively assess the efficacy of surgical correction of angular limb deformities in dogs.Twenty-four dogs were evaluated after surgery for correction of forelimb angular limb deformities. The results are described.

SummaryTwo dogs, both Doberman n pinschers, developed ischiatic nerve palsy following femoral head and neck excisions. Each had undergone surgery entailing the incorporation of a muscle flap (in one case deep gluteal, in the other biceps femoris) to reduce bone-on-bone contact after ostectomy. At later exploratory surgery, the ischiatic nerve was found to be entrapped by muscle in the ischiatic fossa, caudal to the greater trochanter. Partial excision of the ischium relieved the compression, allowing rapid recovery of function. The complication of ischiatic nerve entrapment may warrant consideration when contemplating femoral head and neck excision in cases in which the greater trochanter and ischial tuberosity are abnormally close.Ischiatic nerve palsy developed several weeks after femoral head and neck excision in two Dobermann pinschers. Both dogs had undergone surgery involving muscle sling placement. The ischiatic nerve was found to be entrapped in muscle in each case. Resection of portions of the ischium allowed rapid recovery of function.

SummaryOpen-mout h locking due to lateral impingement of the mandibular coronoid process, lateral to the zygomatic arch, is described in five dogs and one cat. In order to elucidate the underlying cause of this abnormality, radiographs of temporomandibular joints of forty dogs, as well as the case history of a human patient, are compared. Three possible aetiologies are given, namely, flattening of the zygomatic arch, aberrant architecture of the condylar aspects, or contracture of the pterygoid muscle. An effective surgical treatment to prevent recur-rence of coronoid impingement was achieved by ostectomy of the locking part of the coronoid process.Unilateral protrusion of the mandible is described as a veterinary and comparative abnormality in five dogs, a cat and a woman. For the impingement of the coronoid process lateral of the zygomatic arch causing open-mouth locking in the animals, three aetiologies and an effective ostectomy of the coronoid process are given.

SummaryRadio-ulnar synostosis developed in two dogs that had partial mid-diaphyseal ulnar ostectomies performed to correct asynchronous growth of the radius and ulna. The synostosis was apparently painful and caused lameness in one dog, and exacerbated humero-ulnar subluxation in the other dog. Periosteal and interosseous ligament trauma, together with the location of the ulnar ostectomy, radial overstrain and radial hypertrophy were considered to be important factors in the pathogenesis of synostosis formation in these cases.Radio-ulnar synostosis was a complication of mid-diaphyseal ulnar ostectomy in two young dogs.

Kenneth A. Johnson recommendation in every textbook description. A cadaveric study published in this issue of the Journal compared two methods of osteotomy (2). The authors found that use of a sagittal saw produced a smoother ostectomy surface in comparison to the use of an osteotome, which more often produced bone fissures and fragmentation (2). The findings of this study provide an impetus to further evaluate the outcome in clinical patients, using objective measures. Since it is unlikely that availability of total hip arthroplasty will ever eliminate the need for salvage procedures such as femoral head and neck excision, there is a need for more outcomedriven research to evaluate the influence of a range of factors on the success of the procedure, such as surgical technique, surgeon skill, patient factors, and postoperative rehabilitation.

SummaryA newborn llama was referred to our clinic with congenital flexural deformities of both metacarpophalangeal joints. An ostectomy of MCIII-IV was performed bilaterally; reconstruction was done using a dynamic compression plate on the dorsal aspect of the metacarpal bone. Postoperatively a cast was placed up to the carpal region, to provide external immobilisation. A luxation of both fetlock joints was present after the operation and resulted in radiographic arthritic changes. Despite this complication an acceptable degree of healing, without clinical signs of lameness, was achieved.A newborn llama with congenital flexural deformities of both metacarpophalangeal joints was successfully treated by bilateral ostectomy of MC III-IV.

Intermittent open mouth locking occurred in a Persian cat as the result of impingement of the left coronoid process of the mandible on the ipsilateral zygomatic arch. The condition was treated successfully by partial zygomatic arch ostectomy.