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Biomedical subjects

I Macnab

Publications and source records attributed to I Macnab.

At least 19 recordsLinked to original sources
PubMed1991

Chymopapain versus conventional surgery for lumbar disc herniation. 10-year results of treatment.

We reviewed two comparable groups of patients who had been treated for lumbar disc herniation by chymopapain chemonucleolysis (145) or conventional surgical discectomy (91). They were reviewed 10 years after treatment by questionnaire, followed by a personal interview by an independent observer. The results of the surgically treated groups were slightly better than those treated with chymopapain. In particular, there was significantly better early relief of leg and low back pain, and fewer patients needed a second procedure. Complications were few in both groups.

Activities of Daily Living↗
PubMed1988

Nerve root infiltration in the diagnosis of radicular pain.

Clinical and standard radiographic evaluation of patients with lumbosacral radicular symptoms may, on occasion, fail to delineate a cause. This study retrospectively reviews 62 patients who had undergone nerve root infiltration (NRI) and assesses the accuracy and indications for this diagnostic study. Surgical exploration of patients with a Group 1 response (typical pain reproduced by needle placement and then relieved by NRI) confirmed local root pathology in all. Exclusive of patients with arachnoiditis, a Group 1 response showed 85% accuracy in identifying a single symptomatic root. A Group 2 response (typical pain reproduced by needle placement but not relieved by local anesthesia) indicated multiple root involvement. Patients with a Group 3 or Group 4 response (typical pain not reproduced by needle insertion, with or without relief of pain by local anesthesia) were seldom relieved of radicular pain. NRI was most useful in investigation of patients with radicular symptoms in whom other investigations were 1) normal, 2) showed multiple level involvement, or 3) were difficult to interpret because of previous surgery.

Back Pain↗
PubMed1979

Bone ingrowth and stress shielding with a porous surface coated fracture fixation plate.

The extent of bone remodelling under metal fixation plates attached to bone by (i) normal screw fixation and (ii) bone ingrowth into a porous metallic surface underlayer sintered to the metal plate was investigated. Extensive bone remodelling was observed under the integrally bonded porous surface layered plate. This remodelling could be attributed to the more extensive stress transfer from bone to metal plate because of the good bone-to-implant bonding. The importance of stress shielding with high stiffness implants is demonstrated.

Alloys↗
PubMed1978

A porous metal system for joint replacement surgery.

A porous coated chrome cobalt system has been developed to provide long term stabilization in joint replacement surgery. The pore sizes are 50 to 100 microns, thus ensuring sufficient fatigue strength for use in high load bearing situations. Extensive in vitro and in vivo studies have been performed, and a five year follow-up of porous coated total shoulder prostheses has failed to reveal any evidence of loosening. The early results of porous coated hip implants is encouraging.

Animals↗
PubMed1978

Ligamentous laxity and scar formation.

The character of scar tissue is relative to or influenced by ligamentous laxity. Patients who are able to passively hyperextend the terminal interphalangeal joint of the index finger to 45 degrees and beyond have a tendency to leave broad scars. This proved to be statistically significance (p less than .001). It is suggested that in female patients in particular, assessment of the passive hyperextensibility of the terminal interphalangeal joint of the index finger can be used preoperatively to determine whether the patient will be left with a cosmetically displeasing scar following any operative procedure.

Cicatrix↗
PubMed1977

Evaluation of biodegradable ceramic.

An evaluation of a porous biodegradable ceramic, tricalcium phosphate, has been carried out. When implanted in cancellous bone, it is rapidly infiltrated with bone and slowly resorbed. When held rigidly against raw, bleeding, cortical bone, again rapid bone ingrowth occurs. The material does not give rise to any untoward tissue reaction, nor does it cause any systemic reaction. It can therefore be concluded that the material is safe for use in clinical practice, and can be used in specific instances either to replace or to supplement bone grafting.

Animals↗
PubMed1976

The rate of bone ingrowth into porous metal.

Experiments have been devised to study the rate of ingrowth of bone into porous metal with pore sizes up to 100 mu and to study the significance of a gap between the porous metal surface and bone. When the porous coat was in direct apposition with bone, the implant was firmly locked in place after a three week period and the plateau value of implant-tissue shear strength was reached at four weeks. A gap of 1.5 mm between the bone and the implant was bridged by new bone within four weeks.

Animals↗
PubMed1976

Carbon fiber-reinforced bone cement in orthopedic surgery.

A tougher, more fatigue-resistant bone cement consisting of short, highmodulus carbon fibers dispersed randomly in normal ply(methyl methacrylate) bone cement has been developed. Fatigue and impact tests are reported that demonstrate the superior fracture resistance and prolonged load-carrying ability of this system. The use of this carbon fiber-reinforced bone cement in the treatment of a pathological fracture of the femur associated with neoplastic disease of the bone is reported. The tougher cement has provided long-term stability of the fracture.

Bone Cements↗
PubMed1976

Selective ascending lumbosacral venography in the assessment of lumbar-disc herniation. An anatomical study and clinical experience.

Epidural venography was performed in 110 patients with suspected lumbar-disc herniation by catheterization of the ascending lumbar and ascending sacral veins. The findings by venography and by myelography were compared with those revealed by operative exploration. Only sixty-one patients had venography, myelography, and operative exploration. In fifty of these patients with no previous disc surgery, the diagnostic accuracy of venography was 98 per cent and of myelography, 90 per cent. Venography had limited value in the other eleven patients who had had one or more prior disc operations because it did not distinguish between scarring and recurrent disc herniation at the levels previously explored. Selctive ascending lumbosacral venography is indicated both in patients who have not had a prior disc operation, as a guide to whether myelography should be performed when the clinical picture is ambiguous, and in patients whose myelogram is normal or equivocal but whose signs and symptoms are strongly suggestive of disc herniation.

Adolescent↗
PubMed1975

Pyrophosphate arthropathy.

A scanning electron microscopic study of six cases of pyrophosphate arthropathy has been conducted. In the majority of cases the crystals were rectangular. In some cases giant crystals were present. In one case, the crystals were pyramidal. It is concluded that many geometrically different forms of calcium pyrophosphate crystal exist and that the scanning electron microscope is a useful tool in the differentiation of pyrophosphate arthropathy from other forms of crystal synovitis.

Cartilage, Articular↗
PubMed1975

Observations on osteoarthritis of the hip joint.

A correlation of the X-ray changes with the pathological changes seen in arthritic hips obtained at surgery or from cadavers, reveals 6 different patterns of osteoarthritis of the hip. The study suggests that the pathogenesis of the degenerative changes is different in each type and as such, would influence the results obtained by surgical intervention.

Cartilage, Articular↗
PubMed1975

The microhardness of articular cartilage.

The standard metallurgical technique of microhardness testing was useful for investigations on the physical properties of articular cartilage. The problem of visco-elasticity of the cartilage was overcome by using a brittle lacquer coating as a memory device. The surface layer was the hardest plane when the superficial layer was intact. Removal of the superficial layer however, made this plane the softest. There was no variation in hardness with depth. The plane at right angles to the vector of movement of the joint was harder than the plane parallel to the vector of movement. This indicates the presence of a secondary fiber system in the middle layer of articular cartilage. The fibers in this system run predominantly at right angles to the direction of motion of the joint.

Cartilage, Articular↗
PubMed1975

Cervical spondylosis.

Cervical disk degeneration (CDD) can give rise to segmental instability and may appear as pain referred to the arm without any evidence of root compression. CDD can give rise to root pressure either by permitting the development of a disk rupture of by provoking the development of a neurocentral osteophyte, compressing the root in the root canal. Such osteophytes may also compress the vertebral artery. Primary treatment is always conservative. When operative intervention is necessary an anterior cervical discectomy and fusion is preferable to a posterior decompression.

Analgesics↗
PubMed1975

Porous surface layered prosthetic devices.

The method of fabrication and properties of a dual structured implant system consisting of a metallic porous surface layer is described. The ingrowth of bone tissue into the outer porous surface layer results in part fixation, while the solid inner core region provides the necessary mechanical strength for a device used for the replacement of heavy load bearing joint regions such as the hip and knee. Additionally, novel implant systems are suggested using the porous coating concept.

Animals↗
PubMed1975

Use of polymethylmethacrylate to enhance screw fixation in bone.

Pull-out testing of screws inserted into cement and bone under various conditions showed that the cement-screw complex was significantly stronger when the screw was placed in soft cement and the cement was allowed to polymerize without further manipulation. When screw fixation in osteoporotic bone was reinforced with cement, the bone was the weakest component in the system. Fixation under these conditions should be enhanced by increasing the area of contact between the cement and bone. By cooling the cement to prolong its working time, it could be injected with a syringe in such a way that maximum endosteal and periosteal contact was provided.

Bone Cements↗