Acetabular component orientation as an indicator of implant luxation in cemented total hip arthroplasty.

OBJECTIVE: To determine the sensitivity and specificity with which acetabular component angles of inclination and version could be used, alone or in combination, to predict luxation of cemented total hip arthroplasties (THA). STUDY DESIGN: Comparison of retrospectively selected cases and controls SAMPLE POPULATION: All THA performed at the University of Florida between 1991 and 1998 with the BioMedtrix system and for which at least 2 months of radiographic follow-up were available. All THA performed at the University of Georgia with the BioMedtrix system which subsequently luxated. METHODS: Acetabular component inclination angle (IA) and acetabular version angle (VA) were determined for each THA. Data were grouped according to outcome - luxation or no luxation - with the luxated cases from the 2 institutions pooled. Receiver operator characteristic (ROC) analysis was used to evaluate decision rules for using IA and VA as tests for detecting postoperative luxation. Sensitivity and specificity for luxation and 95% confidence bounds were computed with selected values of IA and VA as cut-points. RESULTS: The nonluxation group consisted of 68 THA with a median follow-up time of 5 months (range, 2-60 months). The luxation group consisted of 12 THA with a mean time to luxation of 36 days. The nonluxation group had a mean +/- standard deviation (SD) IA and VA of 40.3 degrees +/- 8.9 degrees and 71.1 +/- 13.6 degrees, respectively, whereas the luxation group had a mean +/- SD IA and VA of 34.7 degrees +/- 12.6 degrees and 72.9 degrees +/- 16.6 degrees, respectively. An IA cut-point of 37.8 degrees achieved 58.3% sensitivity and 57.4% specificity. A VA cut-point of 73 degrees achieved 75.0% sensitivity and 51.5% specificity. IA and VA considered simultaneously achieved a 50.0% sensitivity and 88.2% specificity. CONCLUSIONS AND CLINICAL RELEVANCE: ROC analysis indicated that both IA and VA considered individually or simultaneously were poor indicators of luxation. Although extreme values of IA may predict luxation with high specificity, the potential for luxation cannot be excluded based on apparently appropriate values of IA and VA. The results of this study also indicate that a successful outcome is possible with a wide range of acetabular component positions.

Use of an external ring fixator for correction of an acquired angular limb deformity in a donkey.

Numerous techniques for surgical correction of angular limb deformities in horses involving an osteotomy of the affected bone and stabilization with an internal fixation device have been described. However, because the osteotomy typically has to be performed at the level of the physis, leaving little bone between the physis and the nearest joint, stabilizing the osteotomy by use of internal fixation devices may be difficult. In horses with severe chronic angular limb deformities, the amount of soft-tissue contracture may make it impossible to correct the deformity during a single procedure without causing stretch injuries to the adjacent tendons and neurovascular structures. Adjustable external ring fixators incorporating hinged rods on 1 side of the limb and an angular motor assembly on the other may be useful for treatment of severe chronic angular limb deformities in younger equids, because they allow for gradual correction of the deformity.

Flexor carpi ulnaris (humeral head) muscle flap for reconstruction of distal forelimb injuries in two dogs.

OBJECTIVE: To describe the use of the humeral head of the flexor carpi ulnaris muscle as a rotational flap for reconstruction of distal antebrachial, carpal, and metacarpal injuries in two dogs. STUDY DESIGN: Description of clinical cases. RESULTS: Local rotation of the humeral head of the flexor carpi ulnaris muscle provided coverage of the carpal and carpometacarpal bones and joint structures exposed by soft tissue avulsion. CONCLUSIONS: The distal portion of the humeral head of the flexor carpi ulnaris muscle can be used as a local muscle flap. CLINICAL RELEVANCE: Early soft tissue coverage of large wounds to the carpal and metacarpal regions can be accomplished without resorting to a more technically difficult procedure, such as a free vascularized flap transfer.

Diagnosis of lateralized lumbosacral disk herniation with magnetic resonance imaging.

A left-lateralized, lumbosacral intervertebral disk herniation, which was not apparent on epidurography, was diagnosed in a dog with magnetic resonance imaging. Precise, preoperative localization and characterization of the lesion allowed surgical approach and excision with minimum disruption of surrounding tissues.

Prospective evaluation of ground reaction forces in dogs undergoing unilateral total hip replacement.

OBJECTIVE: To evaluate clinical and biomechanical gait variables in a group of dogs before and after (for 1 year) total hip replacement. ANIMALS: 16 dogs with degenerative joint disease of the coxofemoral joint secondary to hip dysplasia deemed candidates for total hip replacement. PROCEDURE: Before and at 1, 3, 6, and 12 months after surgery, each dog was trotted over a biomechanical force platform. Vertical force data evaluated for each stance phase of the treated and untreated hind limbs included peak force, impulse, and limb loading and unloading rates. Vertical peak and impulse data were also evaluated for the forelimbs. Measurements analyzed in the craniocaudal axis, divided into braking and propulsion phases, consisted of peak force and associated impulses. Also, orthopedic examination for each dog included subjective scoring for limb lameness at each evaluation period. RESULTS: Most ground reaction forces (GRF) were significantly lower before surgery for the proposed treated, compared with the proposed untreated, limb. This difference between limbs continued through postoperative month 1. Also at 1 month, some treated limb values were significantly lower than preoperative values. By 3 to 6 months, treated limb GRF increased so that no significant difference between limbs could be found. Vertical and craniocaudal propulsion impulse values were significantly higher in the treated than untreated limb from the 6-month evaluation period through the remainder of the study. Braking component of the craniocaudal axes measurements was unchanged throughout the study. CONCLUSIONS: GRF indicated that dogs of this study had significantly increased loading function of the treated hind limb by 6 months after unilateral total hip replacement. Data also indicated that some force was transferred from the untreated to treated hip over the study period. Loading rates also increased over the study period, indicating increased willingness to load the treated hip over time. Craniocaudal axis data indicated no improvement in braking forces with coxofemoral joint replacement, suggesting that the coxofemoral joint with degenerative joint disease did not have altered braking performance at a trotting gait. Comparison of subjective lameness scores and objective GRF indicated that visual grading of coxofemoral joint lameness is limited.

Effects of vascular pedicle ligation on blood flow in canine semitendinosus muscle.

Blood flow to the semitendinosus muscle was studied in 12 dogs after ligation of either the proximal or distal vascular pedicle and elevation of the muscle from its normal position. Using 15-micron-diameter radioactive microspheres, flow was measured at rest, 6 and 18 days after muscle elevation and pedicle ligation. Mean blood flow in the proximal region of the muscle 6 and 18 days after ligation of the caudal gluteal (proximal) pedicle was not significantly different from mean blood flow calculated in the middle and distal regions of the muscle. There was also no significant difference in mean blood flow among proximal, middle, and distal regions of the muscle, 6 and 18 days after ligation of the distal caudal femoral (distal) pedicle. There was significantly (P < 0.05) increased blood flow between group-A (ligation of caudal gluteal artery) and group-C (operated-control) muscles, 6 and 18 days after surgery. There was no loss of muscle fiber striations or nuclei, or presence of fibrous tissue that might have indicated ischemic necrosis in any of the experimental groups. These results indicate that the entire semitendinosus muscle can be sustained by the blood flow from either of its 2 vascular pedicles, which reinforces its potential as a muscle flap.

Identification and categorization of the vascular patterns to muscles of the thoracic limb, thorax, and neck of dogs.

Vascular patterns to thoracic limbs, thorax, and neck muscles were studied in 10 dogs (20 limbs) to identify muscles most suitable for transposition in the treatment of large wounds. Gross dissection of injected specimens and angiography were used to identify vascular pedicles. Size and location of pedicles were generally consistent, and any variations would not interfere with most muscle transfers. The cutaneous trunci, latissimus dorsi, sternothyroideus, sternohyoideus, deep pectoral, anconeus, ulnaris lateralis, and ulnar head of flexor carpi ulnaris muscles were identified as suitable for transfer. The cranial trapezius, caudal omotransversarius, cleidobrachialis, and caudal sternocephalicus muscles also had potential for use. Other muscles, because of inaccessibility or unfavorable vascular pattern, were not suitable candidates for transfer.

Applications of a semitendinosus muscle flap in two dogs.

The proximal half of the semitendinosus muscle can be used as a versatile vascularized local transposition flap to reconstruct anatomic faults in the adjacent perineum in dogs. The flap is easy to dissect, and the arc of rotation is considerably beyond the midline. The location, size, and direction of the major vascular pedicle from the caudal gluteal artery is conducive to dependable flap perfusion.

Treatment of trochanteric ulcers with cranial sartorius and rectus femoris muscle flaps.

Five dogs with pressure ulcers over the greater trochanter were treated by debridement and transposition of the cranial part of the sartorius or the rectus femoris muscle. Both muscles had vascular anatomy that allowed transposition based on a major vascular pedicle. All wounds healed promptly by primary intention and no ulcer recurred. The cranial sartorius flap technique was easier to perform than the rectus femoris technique.

Identification and anatomic categorization of the vascular patterns to the pelvic limb muscles of dogs.

The vascular patterns to pelvic limb muscles were studied in 6 dogs (12 limbs) to identify muscles most suitable for transposition in the treatment of large wounds. Gross dissection of injected specimens and angiography were used to identify the vascular pedicles. The vascular pedicles to several muscles were generally consistent, and any variations would not interfere with most muscle transfers. The cranial part of the sartorius, gracillis, semitendinosus, and rectus femoris muscles were identified as suitable candidates for transfer. The caudal part of the sartorius, cranial tibial, and long digital extensor muscles have segmentalized vascular patterns that would limit its arc of rotation.

Antebrachial metacarpal arthrodesis for fusion of deranged carpal joints in two dogs.

Congenital malformation of the carpal joint in a young dog resulted in a progressive lameness. Traumatic disruption of the carpus in another dog resulted in carpal bone necrosis, infection, and chronic instability. Radial metacarpal arthrodesis was performed in both dogs. The diseased carpal bones were excised, sparing the accessory carpal bone in both dogs. Radial metacarpal arthrodeses were then performed, using bone plate fixation. In the dog with the malformed limb, the gait had improved, but intermittent lameness was still present 8 months later because of an associated malarticulation of the cubital joint. The dog with the traumatized carpus had little or no lameness associated with normal activity for 32 months.

A combined tension band and lag screw technique for fixation of olecranon osteotomies.

A combined tension band and lag screw technique for fixation of olecranon osteotomies was used in six canine clinical patients weighing 4.5 to 19 kg. After the proximal part of the ulnar shaft was exposed, a screw hole was drilled and tapped just cranial to the caudal cortex of the olecranon. An osteotomy was performed and the hole in the olecranon fragment was overdrilled to form a gliding hole. For reconstruction, the olecranon was reduced anatomically and compressed with a screw placed in lag fashion. With the trochlear notch exposed, a Kirschner wire was inserted cranial to the screw, using care not to enter the elbow joint. A double-twist figure-eight tension band wire was placed around the Kirschner wire in five dogs and around the screw in one dog. In this dog, a spiked washer was used with the screw because a small olecranon fragment had been produced by incorrect osteotomy position. A painful soft tissue swelling over the prominent washer, which resolved after implant removal, was the only complication attributed to the technique. The combined tension band wire and lag screw technique was a rapid and reliable method for fixation of olecranon osteotomies.

Recovery from severe hydroureter and hydronephrosis after ureteral anastomosis in a dog.

Progressive hydroureter and hydronephrosis were diagnosed in a dog after anastomosis of a crushed ureter. Nephrectomy was averted when partial resolution was noticed one month after the ureteral repair. The appearance of the kidney and ureter was nearly normal several months later. Conservative management should be considered in cases of partial unilateral ureteral obstruction.

Surgical treatment of epulides in dogs: 25 cases (1974-1984).

Epulides were diagnosed and surgically removed in 25 dogs. Histologic examination of the epulides indicated that 40% (10/25) were acanthomatous, 32% (8/25) were ossifying, and 28% (7/25) were fibromatous. Recurrence of the tumor directly resulted in the death of 2 dogs. One of these dogs died of malnutrition 13 months after removal of an ossifying epulis, and regrowth of an acanthomatous epulis that was not resected completely resulted in malnutrition and death in another dog 6 months after surgery. Malignant transformation was observed in a third dog 6 months after removal of an ossifying epulis when an osteosarcoma developed where the epulis had been removed. The range of survival was 6 to 134 months, mean survival time was 43.1 months, median survival time was 49 months, and 1-year survival rate was 92%. Satisfactory long-term tumor control was achieved by aggressive surgical treatment of epulides.

Cervical spinal luxation in two dogs with entrapment of the cranial articular process of C6 over the caudal articular process of C5.

In 2 Poodles, the cranial articular process of C6 was luxated and interlocked dorsal to the caudal articular process of C5. Surgical management in each case included reduction and stabilization of the articular processes, along with limited dorsal laminectomy. One of the dogs was completely normal 4 weeks after surgery, but the other had residual neurologic deficits 11 months after injury.

The effects of halothane-and-oxygen anesthesia, and of halothane-nitrous oxide-and-oxygen anesthesia on tympanograms in the dog.

Electroacoustic tympanograms were recorded from both ears of 20 dogs of either sex, aged 6 mo to 12 yrs, prior to anesthesia, at 10 min after halothane- and-oxygen (HO) anesthesia, and at 5 min after nitrous oxide was added to the HO mixture (HNO). Both HO and HNO anesthesia significantly increased compliance and peak pressure values from pre-anesthetic (own control) values. In addition, HNO anesthesia significantly increased peak pressure values above HO anesthesia levels. HNO compliance values were not significantly different from HO values. These results suggest that tympanograms recorded during either HO or HNO anesthesia in the dog will be altered and that interpretation of the tympanograms should include consideration of the state of consciousness of the animal during recording.

Ventral decompression for caudal cervical disk herniation in large- and giant-breed dogs.

Ventral decompression was evaluated as a treatment for cervical disk protrusion in large- and giant-breed dogs. All of the dogs improved after ventral decompression. After a follow-up period averaging 16 months, half of the dogs were clinically normal and the other half were functional pets despite minor residual proprioceptive deficits. Ventral decompression alone appeared to be acceptable treatment for dogs not having other radiographic signs of caudal cervical spondylopathy.