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Biomedical subjects

M L Porter

Publications and source records attributed to M L Porter.

At least 19 recordsLinked to original sources
PubMed1995

The huckstep nail. Stable fixation of mechanically deficient femoral bone.

A Huckstep intramedullary nail was used to treat 23 fractures in which the femur was mechanically deficient due to pathologic fracture, nonunion, or complex fracture in osteoporotic bone. All nailings were performed by open surgery, and in some cases this was augmented by corticocancellous bone grafting. The Huckstep nail allows the use of multiple cross screws at 15-mm intervals, providing immediate and adequate stability with successful early postoperative weightbearing. The results at followup were good in functional and radiologic terms, with no cases of fixation failure or infection. The quality of instrumentation allowed the nail and screws to be inserted without difficulty; however, the straight profile of the nail may cause problems in the distal femur, as seen in 1 patient. The authors conclude that this device offers significant mechanical and practical advantages over most other forms of fixation, where early weightbearing is desired in the presence of deficient bone. It is not ideal for distal femoral fractures, particularly in the presence of excessive femoral bowing.

Aged↗
PubMed1993

Muscle strength following total hip arthroplasty. A comparison of trochanteric osteotomy and the direct lateral approach.

Twenty-seven patients who had hip arthroplasty operated on with trochanteric osteotomy were compared with 54 patients when the direct lateral approach was used. The strength of the hip abductors, adductors, extensors, and flexors were measured at least 2 years following surgery. The strength of these muscle groups recovered to the same level as those on the nonoperated side, and there was no significant difference between the two groups of patients. Functionally, the direct lateral approach is a safe alternative to trochanteric osteotomy.

Aged↗
PubMed1993

A method for the kinematic evaluation of the knee following anterior cruciate ligament injury and reconstruction.

A quantitative method for assessing the kinematics of the knee in the sagittal plane has been developed in order to evaluate the role of the anterior cruciate ligament following injury and reconstruction. Measurements were made on a series of lateral radiographs obtained at different angles of flexion with the limb weight-bearing and the foot and ankle rotated so that the condyles of the femur overlapped. The kinematics of the joint were then defined by recording the path of the tip of the medial tibial spine as flexion proceeded, using a coordinate system based on the femur. This method overcomes the problems inherent in quantifying knee kinematics by using the pathway of the centre of rotation. In an amputated knee, tibial positions could be specified to within approximately 1.2 mm. There were no significant differences between results obtained at the beginning and end of a six month period for the normal knees of two patients; the standard deviation of the measured tibial positions was approximately 1.6 mm.

Anterior Cruciate Ligament↗
PubMed1993

Long-term results of Charnley low-friction arthroplasty in young patients.

We report the long-term outcome of 218 Charnley low-friction arthroplasties in 141 patients who were 40 years old or younger at the time of surgery. The minimum follow-up was ten years with a mean of 16 years. The probability of the femoral component surviving 20 years was 86% and of the acetabular component, 84%. The chance that both components would survive for this period was 75%. The pathological diagnosis significantly influenced implant survival. In rheumatoid patients the probability of both components surviving at 20 years was 96% compared with 51% in patients with osteoarthritis. Clinical assessment of 103 patients (166 hips) in whom the arthroplasty was still functioning showed that 94% of hips had minimal pain or none. We conclude that in young patients cemented total hip replacement is a good procedure for those with rheumatoid arthritis but that the results are much less reliable in those with osteoarthritis.

Adolescent↗
PubMed1992

Bending and fracture of the femoral component in cemented total hip replacement.

A computer method was used to make 41 measurements on the geometry of insertion of the femoral component in 200 Charnley total hip replacements. Surgery had been performed at least 12 years before, giving results which were classified as: success (90); fracture (56); or loose (54), according to rigid selection criteria. Fracture was associated with heavier patients in which there was poor proximal fixation of the femoral component but adequate distal fixation. Stems with a medial disposition proximally were more common in the fracture group than in the successful or loose groups. Sequential measurements of bending and subsequent fracture were made on the follow-up radiographs of 24 of the 200 cases (6 fracture and 18 successful). These measurements allowed bending to be detected at an earlier stage than by simple inspection of the radiographs.

Aged↗
PubMed1992

Aseptic loosening of the femoral component in cemented total hip replacement.

The purpose of this study was to identify factors which predispose to aseptic loosening of the femoral component in cemented total hip replacement. Its design was based on rigid selection criteria, so that successful and loose replacements which employed the same surgical technique were compared. Measurements of patient anatomy and of the insertion of the femoral component were made, by an accurate computer technique, on initial post-operative radiographs. Loosening was associated with heavier patients with a wider medullary canal which was flared proximally. This difference in anatomy led to differing distributions of cement in the successful and loose replacements. Medial cement-bone demarcation, at the mid-stem level, was also associated with loosening. These findings indicate the importance of optimizing the size of the prosthesis with respect to the femoral morphology.

Bone Cements↗
PubMed1992

Pilon fractures of the wrist. Displaced intra-articular fractures of the distal radius.

22 patients who sustained high energy wrist injuries are reported. These complex injuries resulted in articular disruption of the distal radius. Associated injuries included scapho-lunate dissociation (18%), central die-punch injuries (14%), ulnar fractures (41%) and diastasis at the distal radioulnar joint (23%). Nine fractures (41%) were open and almost a third of patients had other skeletal injuries. All patients were treated by external fixation and reviewed after a mean follow-up of 2 1/2 years. There were no excellent results and only ten good ones (45%). The mean functional impairment was 32%. The external fixator was effective in maintaining extra-articular alignment, but not in ensuring accurate reduction of the articular surface. Residual incongruity of the joint surface was an adverse prognostic feature. All five patients (22%) with an articular step of more than 2 mm. developed symptomatic arthritis. Failure to restore the joint line did not account for all the unsatisfactory results; persistent scapho-lunate dissociation and problems at the distal radioulnar joint were also important.

Adult↗
PubMed1991

Measurement of hip prostheses using image analysis. The maxima hip technique.

A computer-based image analysis system has been developed as a research tool in total hip replacement. The system has been programmed to take multiple measurements from coronal plane radiographs. Poor quality radiographic images can be enhanced and standardised. The measurements which can be obtained include stem subsidence, cup migration, cup wear, and stem loosening. Reproducibility and accuracy were +/- 0.01 mm and +/- 0.5 mm respectively. The present application is in retrospective research, but prospective monitoring of radiographs is planned.

Hip Joint↗
PubMed1989

Prosthetic hip failure: retrospective radiograph image analysis of the acetabular cup.

A method has been developed for quantifying movement and wear of the acetabular component (cup) of total hip replacements (THR) from routine postoperative and review radiographs. The method uses both interactive and automatic computer image analysis techniques. Dimensions of the prosthesis are used to scale the measurements and so overcome variation in radiographic alignment. The application of the method is illustrated by retrospective investigations of cup migration and wear using review radiographs taken over a follow-up of at least 12 years.

Acetabulum↗
PubMed1988

The Essex-Lopresti injury: a variation.

The Essex-Lopresti fracture-dislocation consists of a radial head fracture associated with dislocation of the inferior radio-ulnar joint. We report a variation of this injury in which there was an additional fracture through the scalphoid.

Adult↗
PubMed1988

The boxers' fracture: a prospective study of functional recovery.

The rate of functional recovery following fracture of the fifth metacarpal neck is reported. The recovery of power grip and finger grip strength is complete in most patients by two months. The functional outcome is not significantly related to the degree of angulation at the fracture site.

Adolescent↗
PubMed1984

Functional index: a numerical expression of post-traumatic wrist function.

Accurate functional assessment is an essential part of the analysis of managing fractures. A new technique for the measurement of the wrist's function is described. Observations of a wrist's performance are made using three devices. A dynanometer records movement while acting against a resistive torque. Angular and rotational movement at the wrist is measured using a three-dimensional goniometer. A vigorometer is used to assess the strength of grip. The three derived measurements give a functional index for each patient. Eighty-nine patients sustaining fractures at the wrist were seen at the time of trauma and at an assessment clinic 6 months later. Statistical analysis has shown that all three measurements are necessary to assess function. A functional index has applications in clinical work and research.

Adolescent↗
PubMed1984

Starch synovitis.

Three patients with unexplained synovial inflammation were found to have an ulcerative, granulomatous synovitis on biopsy. Maize starch was identified in giant cells within the granulomata. Starch synovitis has clinical and histological similarities to starch peritonitis, which is thought to be an example of a cell mediated immune response.

Adult↗