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Biomedical subjects

H U Cameron

Publications and source records attributed to H U Cameron.

At least 37 records · Page 2Linked to original sources
PubMed1996

Influence of the Crowe rating on the outcome of total hip arthroplasty in congenital hip dysplasia.

Few studies have examined the relationship between the severity of congenital dysplasia of the hip (CDH) and the clinical outcome of total hip arthroplasty. The authors have used a prospective design to study this question, using the Crowe grade to assess the severity of CDH. There were 71 patients with CDH operated on using the S-ROM total hip (Joint Medical Products, Stamford, CT); the control group was composed of 22 patients without CDH operated on using the same implant during the same period as the CDH patients. The patients with mild CDH did not have a different outcome from the patients without CDH with respect to Harris hip score or limp. The higher the Crowe grade, the more complications occurred. It was also found that the patients in whom the true acetabulum was not used had a significantly higher incidence of limp.

Female↗
PubMed1996

Posterior stabilized knee prosthesis for total knee replacement in patients with prior patellectomy.

OBJECTIVE: To determine the outcome of total knee replacement using a posterior cruciate-substituting knee prosthesis in patients who have undergone previous patellectomy. DESIGN: A cohort study, with a follow-up ranging from 2 to 9 years. SETTING: A university-affiliated institution specializing in elective orthopedic surgery. PARTICIPANTS: Sixteen patients with arthritis of the knee who had had patellectomy. All agreed preoperatively to a prolonged postoperative follow-up. INTERVENTION: A cemented posterior cruciate-substituting knee replacement. MAIN OUTCOME MEASURES: Stair climbing ability, the Hospital for Special Surgery knee rating system for clinical results and a radiologic rating using a zonal system. RESULTS: Clinical rating was 69% good or excellent. Eighty-one percent of patients could use the replaced knee as the lead leg on stair climbing. Minor radiolucency, mostly single zone only, was found. Two patients required revision because of pain, but no obvious reasons for this pain were found at operation. CONCLUSION: In the absence of a patella, a posterior cruciate-substituting prosthesis gives reasonable results.

Aged↗
PubMed1995

Clinical and radiologic effects of diaphyseal stem extension in noncemented total knee replacement.

OBJECTIVE: To determine the clinical and radiologic effects of the addition of a diaphyseal stem extension to the tibial component in noncemented total knee replacement. DESIGN: A cohort study. SETTING: A university-affiliated institution specializing in elective orthopedic surgery. PARTICIPANTS: One hundred and twenty-one patients with arthritis of the knee underwent noncemented total knee arthroplasty with a diaphyseal stem extension. All agreed preoperatively to prolong postoperative follow-up. Forty-six of the patients had a 100-mm stem extension, 56 had a 50-mm stem extension and 19, who had good bone with no intraoperative micromotion, had no stem extension. One patient died 6 weeks after operation and was excluded, leaving 120 knees available for study. Follow-up was 6 months to 3 years. INTERVENTION: Noncemented total knee replacement with the Tricon II prosthesis. MAIN OUTCOME MEASURES: Clinical effects of the diaphyseal stem extension as determined by the Hospital for Special Surgery rating system and radiologic effects as determined by the Cameron classification. RESULTS: Clinically there was little difference between the three groups, with more than 90% in all groups scoring good or excellent. Radiologically, after elimination of single-zone lucency, both stem-extension groups showed a profound decrease in stem lucency. In patients who had a 100-mm stem extension, 90.9% had type IA lucency and 9.1% had type IB; no type II or type III lucency was seen. There was no correlation between radiologic and clinical results. CONCLUSION: The addition of a diaphyseal stem extension to the Tricon II prosthesis reduces the amount of radiolucency in the tibial component in noncemented total knee replacement.

Arthritis↗
PubMed1994

Reflex sympathetic dystrophy following total knee replacement.

Twenty-nine patients who eventually had a diagnosis of reflex sympathetic dystrophy (RSD) following total knee replacement were treated with lumbar sympathetic blocks with local anesthetic. The diagnosis was made based on the complaint of constant pain unrelated to physical activity in the absence of overt sepsis or implant loosening. In six of these cases, other factors may have clouded the diagnosis. Thirteen (44.8%) patients obtained complete relief following an average of 1.8 blocks. Three of these patients had symptoms for more than two years. Twelve patients had complete or partial relief for varying periods of time, but the relief was not sustained. Three obtained no relief at all, and in one the block could not be successfully carried out. This success rate, while shedding no light on the etiology or diagnostic accuracy, has encouraged the authors to continue with this method of treatment in such cases.

Adult↗
PubMed1994

Tibial component wear in total knee replacement.

Polyethylene wear is currently 1 of the major problems of total knee replacement. Evaluation of a large number of revised tibial components showed 3 wear patterns. Symmetrical central and symmetrical posterior wear are rare. Asymmetric wear beginning at the posteromedial part of the tibial plateau is the common pattern. The first step in the main wear process is cold flow of the polyethylene of the posteromedial part of the tibial plateau. The horizontal axis of rotation becomes fixed by this plastic deformation, and wear of the posteromedial part of the plateau then ensues. The vertical axis of rotation also becomes trapped, resulting in external rotation of the tibia on the femur leading to maltracking, exacerbating the wear and leading to an increased volume of wear debris, which eventually leads to chronic synovitis and osteolysis. Wear is more pronounced in the thinner units. Absence of a cruciate gap seems to prevent the initial cold flow and thus minimizes wear.

Humans↗
PubMed1994

The two- to six-year results with a proximally modular noncemented total hip replacement used in hip revisions.

A review of the two- to six-year results of revision cases using a proximally modular noncemented total hip replacement has been carried out. There were 91 cases. A primary stem was used in 29 and a long curved revision calcar replacement stem in 62. The results of the primary cases were 80% excellent, 6% good, 9% fair, and 5% poor. In the revision stem cases, 69.4% were excellent, 11.5% good, 7.6% fair, and 11.5% poor. One primary stem case was revised for acetabular migration. Ten of the revision stem cases were rerevised, four for femoral perforation, three for sepsis reactivation, one for acetabular migration, one acetabular component for dislocation, and one stem for trochanteric nonunion. There have been no stems or sleeve fractures, no implant dissociations and no osteolysis. In those reexplored, no metallosis has been found. Only three cases required structural allografting on the femoral side. These early results are promising and no untoward reactions have occurred as the result of the use of a modular stem.

Adult↗
PubMed1993

The 3-6-year results of a modular noncemented low-bending stiffness hip implant. A preliminary study.

A review of the 3-6-year clinical and radiographic results of a modular noncemented stem has been carried out. This is a three-part stem consisting of a head, stem, and proximal sleeve. The stems are split distally like a clothespin in the coronal plane to reduce bending stiffness. No mechanical failures have occurred, including no bead separation from the single-layer porous-coated taper lock sleeves. Of the 48 cases, 13 had smooth stems distally while the rest were fluted. Five of the fluted stems were solid, that is, nonsplit. Clinical results are 93.7% excellent, 4.2% good, and 2.1% poor with the Harris hip rating. There have been no revisions. Thigh pain incidence with the distal split stem was 4.4%. Radiographic follow-up evaluations revealed nonprogressive radiolucency around one of the ingrowth sleeves. When inserted in varus the smooth stems developed some radiolucency around the distal end. Fluting of the stem appeared to prevent this.

Adult↗
PubMed1993

Noncemented stem tibial component in total knee replacement: the 2- to 6-year results.

OBJECTIVE: To determine if the addition of a stem to the tibial component in noncemented total knee replacement affects sinkage of that component or micromotion. DESIGN: A cohort of 176 consecutive cases with no exclusions. Follow-up ranged from 2 to 6 years. SETTING: A university-affiliated institution specializing in elective orthopedic surgery. PARTICIPANTS: All 176 patients had arthritis of the knee, mainly osteoarthritis. All agreed preoperatively to prolonged postoperative follow-up. INTERVENTION: Noncemented total knee replacement with the Tricon M long-stem tibial component. MAIN OUTCOME MEASURES: Hospital for Special Surgery rating system for clinical results and degree of tibial sinkage and stem lucency seen radiologically. RESULTS: Eight (4.5%) of the 176 prostheses required revision, none for sinkage. Of the remaining 168 knees, 156 (92.9%) scored good or excellent, 6% fair and 1.2% poor. Sinkage occurred in 3%, but was not of sufficient severity to require revision. No lucency was visible in 33.8% of stems, partial lucency in 62%, complete lucency with the lines being parallel to the stem in 3.5% and complete lucency with divergent lines, indicating a loose implant, in 1.7%. Lucency, when present, was seen mainly in the lateral view, seldom in the anteroposterior view. There was no correlation between radiologic results and clinical results. CONCLUSIONS: The addition of a metaphyseal stem reduces the incidence of sinkage of the tibial component in total knee replacement. The stem largely solves the problem of mediolateral micromotion but does not completely prevent anteroposterior micromotion.

Aged↗
PubMed1993

Noncemented, porous ingrowth knee prosthesis: the 3- to 8-year results.

OBJECTIVE: To determine the principal long-term problems encountered in noncemented total knee replacement. DESIGN: A cohort of 252 consecutive cases of total knee replacement with no exclusions. Follow-up ranged from 3 to 8 years. SETTING: A university-affiliated institution specializing in orthopedic surgery. PARTICIPANTS: All 252 patients had arthritis of the knee, mainly osteoarthritis. All agreed preoperatively to prolonged postoperative follow-up. INTERVENTION: Noncemented total knee replacement with the Tricon M prosthesis, which has a metal-backed patella. MAIN OUTCOME MEASURES: The Hospital for Special Surgery rating system for clinical results and the radiologic results, including reasons for revision surgery. RESULTS: Thirty-five prostheses were revised: 11 prostheses because of patellar wear only; in 13 prostheses the tibial component (mainly a 6-mm unit) and patella were revised because of wear; 6 prostheses were revised for sepsis, 4 for reflex sympathetic dystrophy and 1 only for sinkage of the tibial component. Of the remaining 217 prostheses, 88% scored good or excellent, 6% fair and 6% poor. CONCLUSIONS: The single most common cause of failure was polyethylene wear. This was associated with the metal backing of the patella and the use of thin, polyethylene tibial components.

Adult↗
PubMed1993

Dissociation of a polyethylene liner from an acetabular cup.

A polyethylene linear dissociated from a metal acetabular shell that could not be removed at the time of hip revision because the hexagonal hole in its screw head had become rounded off. A high-speed metal cutting burr was used to remove the screw and allow cup revision.

Acetabulum↗
PubMed1993

Double stress fracture of the tibia in the presence of arthritis of the knee.

Two cases of double stress fracture of the tibia are described. Both patients had severe medial compartment arthritis of the knee and some varus bowing of the tibia prior to the stress fractures. The deformities were corrected by tibial osteotomies. Total knee replacement was not required.

Biomechanical Phenomena↗