Biomedical subjects

R R Richards

Publications and source records attributed to R R Richards.

At least 55 records · Page 3Linked to original sources

PubMed1991

Polyethylene synovitis following canine total hip arthroplasty. Histomorphometric analysis.

The synovial membrane response to polyethylene wear debris was analyzed in canine total hip arthroplasties (THA). Fifty-four THAs were performed in healthy, mature dogs. None of the arthroplasties demonstrated clinical or radiographic signs of loosening. Synovial membrane biopsies were harvested 4 (n = 13), 6 (n = 5), 8 (n = 8), 12 (n = 15), and 24 (n = 6) months after surgery and were scored for inflammation, polyethylene (PE) wear debris, histiocyte density, and membrane thickness. The amount of PE wear debris tended to increase with time. However, the inflammatory changes within the joint capsule and synovial membrane did not progress, and the total thickness of the alveolar and surface layers decreased (P = .008). It appears that the amount of wear debris at 2 years in canine hip arthroplasties, without evidence of loosening, is well tolerated by the joint capsule.

Animals↗

PubMed1991

Soft-tissue blood flow after segmental osteotomy of the canine tibia.

The response of soft-tissue blood flow to a segmental osteotomy of the canine tibial diaphysis was investigated. Forty-three dogs underwent unilateral tibial osteotomies to create a 2.5-cm avascular diaphyseal segment, which was then rigidly stabilized with a plate. Blood flow measurements of the limbs that underwent surgery and control limbs were made using cerium 141 microspheres. One month after surgery, blood flow to the caudal musculature was increased 1.4-fold and at 2 and 3 months was twofold the value of the control side. The cranial musculature blood flow was 2.4-fold the control value at 1 month and 1.4-fold the control value at 2 and 3 months. Skin blood flow was significantly elevated at 1 month after surgery (p less than 0.0277), but by 2 and 3 months, skin flow had decreased to 1.4-fold and 1.3-fold of control values (p = 0.22). Bone marrow and cortical blood flows were still significantly elevated at 3 months after surgery. Muscle blood flow remains markedly elevated 3 months after surgery. This study demonstrates the importance of soft-tissue blood flow to the process of revascularization, remodeling, and incorporation of avascular cortical bone.

Animals↗

PubMed1991

Bone grafting with microvascular anastomosis in osteonecrosis of the femoral head.

Vascularized fibular grafting decompresses the femoral head, augments structural stability, and places healthy vascularized bone in the area of femoral head necrosis. Patients are selected for the procedure on the basis of symptomatology, age, mobility of the hip, and radiographic stage of the disease. Twenty-four patients were reviewed in the current report. Mean patient age was 33. Seven patients had stage II disease, 4 patients had stage III disease, 10 had early (less than 2 mm collapse) stage IV disease, and 1 had stage V disease. The mean follow-up was 32.8 months (range, 24-54 months). Five procedures failed. The remaining patients have had gratifying results in terms of pain relief, functional improvement, and cessation of disease progression. Longer follow-up will determine if vascularized fibular grafting alters the natural history of the condition and if vascularization of the fibular bone graft offers superior results to those obtained in the past with nonvascularized grafts.

Adolescent↗

PubMed1991

A comparison of the effects of skin coverage and muscle flap coverage on the early strength of union at the site of osteotomy after devascularization of a segment of canine tibia.

A study was done to compare the effects of coverage with skin and those of coverage with a muscle flap on the early return of strength at the site of an osteotomy after interposition of a devascularized segmental autogenous graft, two centimeters long, from a canine tibia. The bone was fixed with a plate. Thirty-two animals were randomized into two groups, one of which was treated with skin coverage and the other of which was treated with muscle flap coverage. Half of the animals from each group were killed at eight weeks and half, at twelve weeks postoperatively. The tibiae were tested to failure in four-point bending. Failure occurred primarily through the site of the distal osteotomy. Maximum bending load (p = 0.0002) and energy absorbed to failure (p less than 0.02) increased significantly between eight and twelve weeks postoperatively in the group in which a muscle flap had been used for coverage. Bending stiffness was significantly greater at eight weeks in the group in which a muscle flap had been used for coverage than in the group in which skin had been used (p less than 0.03). Maximum bending load was also significantly increased at twelve weeks in the group in which a muscle flap had been used compared with the group in which skin had been used (p less than 0.05).

Animals↗

PubMed1991

Treatment of scaphoid nonunion by radical curettage, trapezoidal iliac crest bone graft, and internal fixation with a Herbert screw.

Ten adult male patients with scaphoid nonunions were treated by radical curettage, trapezoidal iliac crest bone grafting, and internal fixation with a Herbert screw. The mean patient age was 24.7 years, and the mean duration of the nonunion before surgery was 37.3 months. Mean follow-up time was 30.4 months. Nine of the ten nonunions healed, although one patient required a second bone-grafting procedure. The mean postoperative grip strength was 45.0 kg, and the mean postoperative pinch strength was 11.5 kg. The mean postoperative range of motion was volar flexion, 76.1 degrees; dorsiflexion, 74.2 degrees; radial deviation, 22.1 degrees; and ulnar deviation, 40.1 degrees. The scapholunate angle decreased from a mean of 72.8 degrees preoperatively to 60.6 degrees postoperatively (p less than 0.025). The mean carpal index was 0.57 postoperatively. Mean scaphoid length increased postoperatively and was within 0.2 mm of the opposite (normal) scaphoid in every patient except the single patient with a persistent nonunion (p less than 0.025). All patients returned to work (eight as laborers), and nine of ten wrists were subjectively rated as good or excellent. The results of the series suggests that treatment of displaced scaphoid nonunion by radical curettage, trapezoidal iliac crest bone grafting, and internal fixation with a Herbert screw is an effective method of treatment that reconstitutes scaphoid anatomy and promotes excellent wrist function.

Adult↗

PubMed1990

Internal fixation of a capitate fracture with Herbert screws.

A case of an isolated, displaced fracture of the capitate is described. This rare carpal injury was treated by internal fixation with two Herbert screws. The fracture united and the patient achieved an excellent range of wrist motion. The Herbert screw is useful in the treatment of displaced fractures of the capitate since the screw maintains reduction, compresses the fracture site, and allows early wrist motion.

Adult↗

PubMed1989

Effect of muscle flap coverage on bone blood flow following devascularization of a segment of tibia: an experimental investigation in the dog.

Severe tibial fractures may be associated with soft tissue loss, devascularization of cortical bone, and significant morbidity. Local rotational muscle flap coverage is used to obtain coverage of acute open tibial fractures and to treat chronic osteomyelitis of the tibia. The purpose of this study was to determine (a) the longitudinal and cross-sectional regional blood flow characteristics of the canine tibia and (b) whether a muscle flap was superior to vascularized skin coverage in restoring blood flow to devascularized canine tibial cortex. A 2.5-cm segment of tibia between two standardized osteotomies was devascularized. The segment was replaced anatomically and stabilized with a plate. The animals were divided into two experimental groups: (a) skin coverage (n = 8), and (b) muscle flap coverage (n = 8). Thirty-one days postoperatively Ce141 microspheres were injected to measure bone blood flow. The tibial diaphysis was divided into proximal, middle (devascularized), and distal segments. The unoperated leg was used as a control. In the control tibiae, the middle segment was less vascular than either the proximal or distal segment and no difference between anterior and posterior cortical blood flow was observed. Blood flow to the devascularized segment of tibia was significantly greater when it was covered with a muscle flap (p less than 0.025). The most significant increase in bone blood flow in the muscle flap coverage group versus the skin coverage group occurred in the anterior cortex of the tibia (p less than 0.005). This may be clinically important since the soft tissues over the anterior tibia are commonly deficient following open fractures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Medial epicondylitis caused by injury to the medial antebrachial cutaneous nerve: a case report.

A 35-year-old man who had chronic elbow pain due to medial epicondylitis received a steroid injection into the medial epicondyle. This was followed immediately by increased pain and symptoms of dysesthesia in the distribution of the medial antebrachial cutaneous nerve. On surgical exploration 9 months later, the nerve was found to lie directly over the medial epicondyle and appeared to have sustained an injection injury. This report draws attention to the fact that because the posterior division of the medial antebrachial cutaneous nerve may lie directly over the medial epicondyle, it may be at risk of direct injury if injections are given into the epicondyle.

Adult↗

PubMed1989

Treatment of painful scapulothoracic crepitus by resection of the superomedial angle of the scapula. A report of three cases.

Three healthy young male manual laborers developed painful unilateral scapulothoracic crepitus arising from the superomedial angle of the scapula. There was a history of trauma in two of the patients. Asymmetric prominence of the superomedial angle of the scapula was demonstrated by computed tomography (CT) scanning in two patients. All three patients were successfully treated by resection of the superomedial angle of the scapula. The resected tissue was histologically normal in each case. Painful scapulothoracic crepitus arising from the superomedial angle of the scapula is associated with local trauma, is best investigated with a CT scan, and if unresponsive to prolonged conservative measures, can be successfully treated by resection of the superomedial angle of the scapula.

Adult↗

PubMed1988

Internal fixation of an unstable open fracture of a distal phalanx with a Herbert screw.

A 20-year-old patient was seen with an unstable, infected, open fracture of the distal phalanx of the long finger of the right dominant hand. The patient was treated by removal of the nail, debridement of the fracture site, and stabilization of the fracture with a Herbert screw. The Herbert screw compressed the fracture site and allowed early active motion of the distal inter-phalangeal (DIP) joint. The wound healed without incident, and the fracture was radiographically united 6 weeks after the procedure. The Herbert screw is useful in the treatment of unstable fractures of the distal phalanx, since the screw maintains reduction, compresses the fracture site, and allows early active motion of the DIP joint.

Adult↗

PubMed1988

Thoracic outlet syndrome with congenital pseudarthrosis of the clavicle: treatment by brachial plexus decompression, plate fixation and bone grafting.

Although a number of cases of congenital pseudarthrosis of the clavicle have been described in the literature, they provide little direction for the treatment of this condition when it is associated with thoracic outlet syndrome. The authors describe their experience with such a case in a 20-year-old woman. Symptoms of pain in the ulnar distribution of the right forearm and discoloration of the hand with abduction of the extremity had developed over 3 years. The radial pulse was obliterated by abduction of the arm. Exploration of the brachial plexus revealed a constricting band arising from the distal fragment of the clavicle running to the first rib which, together with the mass of the pseudarthrosis, comprised the thoracic outlet. The patient was successfully treated by division of the fibrous band, reduction of the clavicle, internal fixation with a plate and iliac crest bone grafting. At follow-up the patient had a full range of motion in the shoulder and was asymptomatic.

Adult↗

PubMed1988

Shoulder arthrodesis using a pelvic-reconstruction plate. A report of eleven cases.

Eleven adults who had a flail shoulder due to brachial plexus palsy had arthrodesis of the shoulder using a single ten-hole pelvic-reconstruction plate. Both the glenohumeral and the acromiohumeral joints were fused with the shoulder in the position of 30 degrees of abduction, 30 degrees of flexion, and 30 degrees of internal rotation. No bone graft was used. The patients were immobilized in a spica cast for six weeks postoperatively. At an average follow-up of twenty-five months after the operation, the position of the arthrodesis had been maintained and solid fusion had occurred in each shoulder. No patient required removal of the plate. The pelvic-reconstruction plate is malleable and is more easily contoured in the operating room than a dynamic-compression plate. We recommend the use of a malleable pelvic-reconstruction plate when performing arthrodesis of the shoulder.

Adult↗

PubMed1987

The influence of muscle flap coverage on the repair of devascularized tibial cortex: an experimental investigation in the dog.

Segments (2 cm) of canine tibial diaphyseal bone were devascularized and internally fixed with a plate. The medial cortex of the devascularized tibia was covered with skin in one experimental group (n = 7) and a local muscle flap in the other (n = 6). The animals were given intravenous fluorochrome dye and killed 42 days postoperatively. Enveloping callus formed around the cortex which was repaired by the formation of resorptive cavities on its external surface. New bone formation occurred within the resorptive cavities. Muscle flap coverage was associated with a sixfold increase in cortical porosity (p less than 0.005) and a fourfold increase in the area of enveloping callus (p less than 0.05). The area of intracortical new bone formation was greater in the cortex with muscle flap coverage (p less than 0.05). The maximum depth of intracortical new bone formation increased from 0.46 +/- 0.14 mm with skin coverage to 0.95 +/- 0.14 mm with muscle flap coverage (p less than 0.001). This study demonstrates that muscle flaps are superior to skin coverage in initiating the repair of devascularized cortical bone.

Animals↗

PubMed1987

Internal fixation of capitellar fractures using Herbert screws: a report of four cases.

Four patients with displaced fractures of the capitellum (capitulum humeri) were treated by open reduction and internal fixation using Herbert screws. The mean follow-up was 16 months (range from 12 to 21 months). All fractures united without evidence of avascular necrosis. Postoperatively, the range of motion was excellent, except in one patient who had a comminuted open fracture and other injuries. Three cadaveric dissections demonstrated that the Herbert screw could be inserted without detaching the lateral collateral ligament. The Herbert screw is useful in treating displaced capitellar fractures since the jig maintains the reduction and the screw, compressing the fracture site, is buried beneath the articular cartilage and does not have to be removed.

Adult↗

PubMed1987

Biologic response to uncemented Madreporic canine hip arthroplasty.

The Madreporic hip arthroplasty has provided encouraging clinical results. The surface of the prosthesis is unlike other uncemented prostheses since the rough surface is formed by multiple 1-mm diameter beads that are cast as an integral part of the prosthesis and increase its surface area four times. Seven Madreporic hip arthroplasties were implanted in adult male mongrel dogs. Specimens were harvested 5, 6, 9, 12, 20 and 52 weeks after insertion. One specimen became septic and loosened. The prosthesis was stabilized initially by friction fit between the prosthesis and the endosteal cortex of the proximal femur. Dense, uniformly organized, fibrous tissue surrounded the prosthesis at 5 weeks. The fibrous tissue appeared similar to Sharpey's fibres. Circumferential bone contact increased from 26% at 5 weeks to 60% at 52 weeks. Fluorescent labelling revealed active new bone formation within the interstices of the prosthesis without evidence of an intervening soft-tissue membrane. Firm mechanical anchorage of the Madreporic femoral prosthesis was demonstrated in this study.

Animals↗

PubMed1987

Radiocarpal osteoarthritis associated with bilateral bipartite carpal scaphoid bones: a case report.

Bipartite carpal scaphoid is a rare congenital anomaly. The authors report on a 56-year-old man who presented with bilateral wrist pain without a history of trauma. X-ray films demonstrated bilateral symmetric bipartition of the scaphoid into a large distal ossicle and a smaller proximal ossicle. There was degenerative change in the articulation between the distal ossicle and the radial styloid. The joint space between the proximal ossicle and the scaphoid fossa was preserved. The absence of periscaphoid degenerative change has been suggested as a criterion for the diagnosis of congenital bipartite scaphoid. This patient fulfilled all other criteria for the diagnosis and the authors suggest that degenerative change developed due to abnormally high contact force between the distal ossicle and the radial styloid. An identical pattern of degenerative change has been observed in long-standing nonunion of the scaphoid, likely due to a similar mechanism. Radiocarpal osteoarthritis can develop in patients with congenital bipartition of the scaphoid and is similar to that observed in long-standing nonunion of the scaphoid.

Carpal Bones↗

PubMed1986

Effect of hydrostatic dilation on the structure and patency of small arteries.

The effect of hydrostatic dilation on the structure and patency of 40 rat femoral arteries was investigated. The femoral arteries were hydrostatically dilated, following cannulation of a side branch, with heparinized Ringer's lactate to a pressure of 300 mmHg. Arterial patency, morphometry, and histology were assessed immediately, 24 hours, 48 hours, 7 days, and 14 days following dilation. Hydrostatic dilation caused an immediate 85 percent increase in intraluminal diameter (p less than 0.001) and an immediate 39 percent decrease in wall thickness (p less than 0.001). All the dilated arteries remained patent, although two developed intraluminal thrombus that partially obstructed the lumen. Hydrostatic dilation did not disrupt the cell layers of the arterial wall. The smooth muscle cells of the media were lengthened and showed diffuse necrosis at 24 and 48 hours. Margination of white blood cells was observed in all specimens at 48 hours. Nuclear regeneration in the smooth muscle of the media was first observed at seven days and was present throughout the media at 14 days. Wall thickness increased between 7 and 14 days due to intimal hyperplasia (p less than 0.01). Hydrostatic dilation is shown to be an effective means of increasing intraluminal diameter, but the pathologic changes initiated in the arterial wall militate against its use in the clinical setting.

Animals↗

PubMed1986

Influence of soft tissue coverage on the healing of cortical defects in canine diaphyseal bone.

The influence of soft tissue coverage on bone healing was investigated in dogs. A standard diaphyseal bone defect was left open, closed with skin, or closed with skin and muscle. Specimen radiography, callus morphometry, microscopy, and fluorescent microscopy were used to assess bone healing. The defects healed in all groups. Defects left open produced significantly more periosteal callus (p less than 0.01). Abscess formation was observed in the callus. The trabecular structure was abnormally oriented. Histomorphometric measurements of the rate of bone formation were the same regardless of the presence or type of soft tissue coverage. Failure to disturb the intramedullary blood supply may have minimized the differences in healing among the 3 groups. Nevertheless, soft tissue coverage was observed to prevent bone infection and to accelerate the restoration of normal cortical architecture.

Animals↗