Search PubMed⌕ Search

Biomedical subjects

L D Dorr

Publications and source records attributed to L D Dorr.

At least 91 records · Page 5Linked to original sources
PubMed1990

The bipolar endoprosthesis and bone graft in the management of aseptic acetabular component loosening.

Ten patients with large acetabular defects underwent hip arthroplasty revision with the use of allografts in conjunction with a bipolar prosthesis. Six patients had solid femoral head allografts and the others, morselized allografts. Radiographs at 2-year follow up showed an average of 8 mm of superior migration and 4 mm of medial migration. Our experience has shown that bipolar revision arthroplasties tend to migrate against the allograft. We recommend that bipolar revisions be limited to small acetabular defects that give the bipolar prosthesis full rim contact.

Adult↗
PubMed1990

Anatomic Porous Replacement hip arthroplasty: first 100 consecutive cases.

One hundred consecutive Anatomic Porous Replacement (Intermedics Orthopaedics, Austin, TX) hip replacements were followed for 4 years. Eighty percent of patients had bone ingrowth fixation, 14% stable fibrous, and 6% unstable fibrous (loose) with 4% revised. Only two hips changed fixation grade after 2 years. Bone remodeling showed cancellous hypertrophy of the cortex, usually along the lateral cortex, and 7% had stress shielding (atrophy) of the proximal cortices. Adaptive bone remodeling almost always occurred in type B and C bone. Bone remodeling was statistically related to bone type, prosthetic fill, stem-bone ratio, and collar loading. We concluded that proximal bone ingrowth fixation with proximal load transfer provides good clinical results and excellent bone remodeling. Also, collar loading improves bone response. To expand this fixation in a predictable fashion to all type B and some type C bone requires geometry changes, which have been accomplished in the Anatomic Porous Replacement II.

Adult↗
PubMed1990

Histologic, biochemical, and ion analysis of tissue and fluids retrieved during total hip arthroplasty.

Large amounts of metal and polyethylene debris and high ion readings are found in capsule and fibrous membranes of both loose titanium and cobalt-chromium stems. Prostaglandin E2, interleukin-1, and collagenase levels are elevated when compared to control values with collagenase having the highest and most consistent elevations. Synovial fluid and blood ion readings were elevated in loose cemented and cementless stems made from both materials. Blood ion readings were not elevated in fixed stems. Fixed stems had much less particulate debris in soft tissues. The data showed that failure of most metal hip stems was initially due to a mechanical cause, with high debris and ion counts occurring secondarily in capsule and fibrous membranes. Particulate debris and high ion readings are primarily a focal problem contained by the periprosthetic fibrous connective-tissue encapsulation within the femoral canal and joint capsules. No systemic problems were manifest in any of the patients examined and followed in this study.

Aluminum↗
PubMed1990

Five-year postoperative results of cemented femoral arthroplasty in patients with systemic bone disease.

To determine whether bone cellular abnormality affects the results of cemented femoral arthroplasty, 21 patients had biopsies of the iliac crest and femoral cortex at the time of surgery. Roentgenographic and histomorphometric studies were used to characterize fibrous membrane formation, cancellous bone, calcar resorption, and bone turnover. Patients with high bone turnover and decreased femoral thickness and density before surgery were at risk of developing calcar resorption and cancellous diaphyses, conditions that weaken proximal stem support and lead to early failure. These findings suggest that noncemented stems may be indicated in this group. Another group, osteoporotic patients, suffered from osteoblastic insufficiency, which may be the indication for the use of cemented stems rather than noncemented stems, which require bony ingrowth.

Aged↗
PubMed1990

Total hip arthroplasties in patients younger than 45 years. A nine- to ten-year follow-up study.

Eighty-one cemented total hip arthroplasties in patients younger than 45 years were reviewed with an average 9.2-year follow-up interval. The results were compared with the same group previously reported at an average follow-up time of 4.5 years. Clinically satisfactory results were 58% compared with 78% at 4.5 years. The revision rate almost tripled to 33%. Impending failure was present in 56% of those hips not yet revised. In the first study, technique was a primary determinant of success. In this report there was no influence of technique on the incidence of revision. Age did not influence revision rates either, with 35% in patients younger than 30 years and 32% in patients aged 30-45 years. Patients younger than 30 years had fewer satisfactory clinical results and a higher rate of impending failure. As in the first study, the best results were obtained in patients with inflammatory collagen disease aged from 30 to 45 years.

Adult↗
PubMed1989

Reimplantation of infected total hip arthroplasties in the absence of antibiotic cement.

Twenty-two patients with deep infection of the hip were reimplanted and followed for a minimum of 3 years. All reimplantations were done without antibiotic-impregnated cement. Nine were done using cemented and 13 using cementless components. Two patients had recurrent infection. Both of these had primary Pseudomonas infections and had cemented revisions. At 3 or more years, 91% of patients are infection-free as determined by clinical evaluation, erythrocyte sedimentation rate, and, in a few, aspiration. Cemented hips had less pain than cementless hips, although both had equivalent functional scores. The significance of these findings is that reimplantation of infected hips can be successfully accomplished without antibiotic-impregnated cement. Cementless fixation can therefore be used. Clinical results with cementless hips for reimplantation will improve with current designs and techniques.

Aged↗
PubMed1989

Fat emboli in bilateral total knee arthroplasty. Predictive factors for neurologic manifestations.

Fat embolism after bilateral total knee arthroplasty (TKA) occurred in 12% of the authors' patients having bilateral TKA with intramedullary instrumentation. Usually embolism was manifested as neurologic changes, most often changes of mental status. Death is a potential consequence, and this occurred in one patient. The present authors believe that fat embolism is not predictable preoperatively and propose that intraoperative guidelines can be used to reduce risk of this complication. Intraoperative monitoring by a Swan-Ganz catheter will permit measurement of the pulmonary arterial pressure, pulmonary vascular resistance, and pulmonary capillary wedge pressure. A sustained rise of any of these would be an indication to abort the second knee operation. If Swan-Ganz catheter is not available, a sustained fall of oxygen saturation to 90% or lower can be used as a criterion. The risk for fat embolism is increased with the use of intramedullary instrumentation, and the above guidelines are recommended for operations with this type of instrumentation. A fluted intramedullary rod and vent holes should be used.

Catheterization, Swan-Ganz↗
PubMed1989

Bone grafts for bone loss with total knee replacement.

Predictable and reproducible use of bone graft for reconstruction of defects with total knee replacement requires (1) surface preparation of host bone to expose a viable bony bed, (2) definition of the defect and preparation of the graft so that excellent fit and fixation are obtained, (3) coverage of the graft by the component to prevent resorption of unstressed graft which may compromise the press-fit of the graft and lead to failure by collapse, (4) protection of the graft from overload by correct alignment of components and limb and by limited weight-bearing until union occurs, (5) protection of the graft by use of a stemmed component when indicated. In the knee, bone grafts can be expected to be successful in 90 to 95 per cent of patients if the above principles are followed. Failed grafts can be salvaged by a second graft or by use of custom components if the bone is judged to have united.

Bone Cements↗
PubMed1989

Rationale of the Knee Society clinical rating system.

A new total knee rating system has been developed by The Knee Society to provide an up-to-date more stringent evaluation form. The system is subdivided into a knee score that rates only the knee joint itself and a functional score that rates the patient's ability to walk and climb stairs. The dual rating system eliminates the problem of declining knee scores associated with patient infirmity.

Disability Evaluation↗
PubMed1988

Functional comparison of posterior cruciate-retained versus cruciate-sacrificed total knee arthroplasty.

Gait of 11 patients with bilateral paired posterior cruciate-retaining and cruciate-sacrificing total knee arthroplasties (TKA) was studied preoperatively and two years postoperatively on walking and stair climbing. Five-year clinical and roentgenographic examinations were included in the study. Differences between the two prostheses were noted both in level walking and in stair climbing. On level walking, cruciate-sacrificed TKA had more flexion in loading response and increased flexion and varus moments with increased muscle activity of quadriceps and biceps femoris. Abnormal gaits common to both types of knee were decreased flexion in stance and decreased single-limb stance. Both knees had a stiff-legged gait during stance. On stairs, the cruciate-sacrificed TKA substituted soleus muscle activity for knee stability. The single-limb stance and range of motion were similar for both knees. In clinical terms, the cruciate-sacrificed TKA is less efficient and has greater medial loading and higher joint reaction forces that may affect durability of the prosthesis. The five-year knee scores, patient satisfaction, and roentgenographic examinations were equal for both sets of knees.

Adult↗
PubMed1986

Treatment of femoral neck fractures with total hip replacement versus cemented and noncemented hemiarthroplasty.

A prospective study of displaced femoral neck fractures was conducted with patients randomized into three groups: cemented total hip replacement (THR), cemented hemiarthroplasty (UHR-C), and noncemented hemiarthroplasty (UHR-NC). Eighty-nine patients were treated for displaced (Garden type 3 or 4) fracture with a prosthesis; 39 patients had THR, 37 had UHR-C, and 13 had UHR-NC. No difference was found in the level of pain, ambulation, or aids required between the THR group and the UHR-C group, except for active community ambulators, who demonstrated decreased endurance capability when treated with UHR-C. The patients treated with UHR-NC had increased pain and decreased ambulation and required assistive devices. The most significant complication was dislocation, which occurred in 7 patients with THR and 2 with UHR-C. The mortality rate at 2 years was 18%; all but two of the deaths were in patients with one of five different medical diseases: clinically significant cardiac or pulmonary disease, cancer, alcoholism, or psychosis. The mortality rate was insignificant in patients younger than 70 years of age. Roentgenographic review showed only 2 of 76 cemented stems with progressive cement-bone demarcation, with one patient requiring revision for a loose prosthesis. No evidence of protrusio was seen with the use of the bipolar cap. The uncemented hemiarthroplasties demonstrated lucency between the metal and bone in the proximal femur in 9 of 13 stems. The authors make recommendations regarding hip replacement.

Adult↗
PubMed1986

Resection arthroplasty following infected total hip replacement arthroplasty.

Thirty-nine patients with 41 hips with resection arthroplasty for infected total hip replacement arthroplasty were evaluated for functional level and factors that contribute to that level. Eighty-three percent were either minimal community ambulators or nonambulators, and only two patients walked without assistive devices. At last follow-up, 93% of the patients had pain in their hips. The best function was obtained in patients with a healed wound and heterotopic ossification. The worst functional result was in patients with chronic drainage. Fifteen of the patients with resection arthroplasties had foot-switch studies to determine gait velocity and single-limb stance time. Ten patients also had oxygen consumption studies performed. The average gait velocity was 35 m/minute (41% of normal). The average oxygen consumption was 0.41 ml/gm (264% normal) with an average heart rate of 121. The energy consumption was greater than that recorded in patients with above-knee amputation.

Adult↗
PubMed1986

Bone graft for tibial defects in total knee arthroplasty.

Twenty-four knees with bone grafts for tibial defects at the time of either primary or revision total knee arthroplasty were followed for three to six years. With 22 of 24 bone grafts, union and revascularization were seen and no clinical collapse was present. In two, nonunion occurred, accompanied by collapse in one. Failure was attributed to varus alignment of the leg in one (a medial condylar graft) and to insufficient preparation of the bony bed in the second (bleeding bone was not exposed). Evidence for incorporation of the grafts was obtained by tomogram, bone scan, and bone biopsy. Incorporation was present by six months, but the time to complete remodeling was not determined. A bone graft is recommended for tibial defect involving 50% or more of the bony support of either tibial plateau. A bone graft is indicated whenever a cement column under the prosthesis would measure more than 5 mm in height.

Aged↗
PubMed1986

Technical considerations in total knee arthroplasty.

Results with total knee arthroplasty as published in this issue show few mechanical failures in knees correctly aligned. If the principles of technique are respected, the narrow limits for margin of error can be met. To provide optimal results, the following measures are recommended. The tibia should be cut no more than 5 mm from the medial subchondral bone, if the posterior cruciate ligament is sacrificed, and between 5 mm and 8 mm, if the posterior cruciate is saved. Fill a defect as necessary with bone graft. The tibia should be cut 90 degrees to its axis in the medial-lateral plane and with 5 degrees posterior tilt. Maintain the anterior-posterior height of the femur to ensure flexion stability. Use the distal femur as the "adjustment cut" even if the joint line is elevated. If the posterior cruciate ligament tension is tight, lengthen the ligament or convert to a sacrificing design. Deformity should be corrected with soft tissue release and not angular bone cuts. The patella cut should be performed so that the result is a symmetrical patella that is not increased from its anatomic height. If these principles are followed, the instrumentation use and order of osteotomy of the distal femur or tibia do not matter.

Bone Transplantation↗
PubMed1985

Functional evaluation of total hip arthroplasty with five- to ten-year follow-up evaluation.

Forty-seven patients with unilateral hip disease had a preoperative and postoperative gait analysis of total hip arthroplasty with a follow-up period of five to ten years. The object was to correlate the levels of function with mechanical loosening. Unilateral total hip arthroplasty in uncomplicated patients restored function to 80% of normal over a two- to four-year period. Patients followed longer than five years appeared to have an accelerated decline in function unassociated with pain. No Class C patient, regardless of age or gait velocity, developed loosening or required revision of the hip prosthesis. Survivorship studies revealed an 85%-90% incidence of loosening by the seventh postoperative year in Class A patients 55 years or younger and those walking preoperatively at more than 50% of normal gait velocity. In these same two groups of patients, the probability of revision for mechanical failure by ten years is 58% for age and 66% for fast walkers. The majority of patients in this study had a technical rating not acceptable by present standards so that these results represent most likely the worst prognosis for longevity of total hip arthroplasty. In high-risk patients, protected ambulation with crutches for six months postoperation may improve their prognosis.

Female↗
PubMed1984

Factors influencing the intrusion of methylmethacrylate into human tibiae.

Three commonly used bone cements were inserted into tibiae from human cadavers to investigate techniques for optimal intrusion with manual pressurization. In each tibia the medial plateau was cleansed by pulsating water lavage, and the lateral plateau was cleansed by syringe only. Acrylic was inserted at one-minute intervals through four minutes, at which time intrusion decreased steeply. Intrusion was superior in bone prepared by pulsating lavage. Mixing the acrylic for no longer than three minutes prior to insertion by manual pressurization into bone prepared by pulsating lavage is suggested. Clinical use of this technique has improved intrusion, as evidenced by postoperative roentgenograms. As compared with interfacial strengths and depth of intrusion as reported in the literature, the penetration achieved with this technique gives an optimal depth of intrusion (2-4 mm) for adequate strength of the bone-cement composite. A new photographic computer technique is introduced for study of the intrusion of methylmethacrylate into bone. Differences in bone density can be accounted for by this technique, and the correlation coefficient to direct bone biopsy is 0.92.

Cadaver↗
PubMed1983

Classification and treatment of dislocations of total hip arthroplasty.

A review of 39 dislocations of total hip arthroplasties revealed three causes: positional (Type I); soft tissue imbalance (Type II); and component malposition (Type III). Forty-one percent of hips had a single dislocation, and 59% had multiple dislocations. Reoperation was performed in 42%, with 28%, mostly Type III problems, requiring revision; all had had multiple dislocations. Forty percent of the dislocations resulted in complications that were primarily the result of bedrest for treatment. Based on the cause of dislocation, to reduce complication, component positions are determined by roentgenographic analysis. Positional dislocations (the patient assumes a position that exceeds the mechanical stability of the prosthesis) are treated by four to six weeks' use of the hip brace, which limits flexion and adduction. Soft tissue imbalance, most often a result of failure of fixation of the greater trochanter or an excessive femoral neck cut, can be treated initially by a brace. If recurrent dislocations occur, reattachment of the trochanter and/or revision to a long-neck prosthesis should be considered. Component position errors were successfully treated without revision only if a single acetabular error was present. If the acetabulum is malpositioned in two planes or severe retroversion of the femoral component is present, immediate revision is advisable.

Adult↗