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Biomedical subjects

L D Dorr

Publications and source records attributed to L D Dorr.

At least 55 records · Page 3Linked to original sources
PubMed1996

Natural history of femoral focal osteolysis with proximal ingrowth smooth stem implant.

Focal femoral osteolysis has become a prominent cause of failure of total hip arthroplasty. Femoral focal osteolysis is studied in 185 hips with a patched porous-coated titanium femoral stem. Seventy-two hips had osteolysis and 113 did not. Seventy-one percent of osteolysis is evident on radiographs by 6 months to 5 years after surgery. The location is most commonly seen on an anteroposterior radiograph, with proximal osteolysis most common and the initial size of defects being greatest in zones 2, 3, 5, and 6. Progression of size is slow, with each focal defect averaging 0.89 mm/y. Progression of bone loss occurs more commonly with the occurrence of new defects rather than extension of an existing defect. Focal osteolysis was directly correlated with the amount of polyethylene wear. Osteolysis is more likely when linear polyethylene wear exceeds 0.2 mm/y or volumetric wear exceeds 150 mm3/y or when the patient is below age 60. Accelerated wear and osteolysis occur most often when the fixation of the arthroplasty is poor.

Adult↗
PubMed1996

Comparative results of a distal modular sleeve, circumferential coating, and stiffness relief using the Anatomic Porous Replacement II.

One hundred forty-eight primary Anatomic Porous Replacement II (APR-II, Intermedics Orthopaedics, Austin, TX) noncemented total hip arthroplasties were studied at follow-up periods of 2 to 5 years. Because the stem geometry has not changed since 1988, it was possible to study three adjunctive criteria for porous-coated hip arthroplasties. The APR-II stem geometry was used in three groups: APR-II stem in 56 hips, APR-IIS stem with distal sleeve in 44 hips, and APR-IIT stem with circumferential coating and hollow stem in 48 hips. The APR-IIT was followed 2 years; the APR-II and APR-IIS were followed an average of 3.4 years (range, 2-5 years). For comparison of the results within these three groups 2-year results were compared. The results of the APR-II and APR-IIS at the last follow-up examination are also reported. There was no statistical difference within the three groups for any clinical comparison: 82% had excellent results, 14% good, 2% fair, and 2% poor. At the 2-year follow-up examination, radiographic fixation of the APR-IIS was worse than that of the APR-II and APR-IIT (P < .0005). The APR-IIS uses a distal sleeve, which results in an adverse stiffness ratio between bone and stem. Fixation of the APR-IIT was better than that of the APR-II (P < .0005), probably because the APR-IIT had an increased volume and circumferential level of porous coating and was hollowed for stiffness relief. At final follow-up examination, fixation of the APR-IIS was still worse than that of the APR-II (P < .0005). There was no progressive loss of fixation for either the APR-II or APR-IIS between 2 and 5 years. Only 1 of 148 patients was revised for osteolysis. No other stem or acetabular component is loose. The adjunctive use of a modular sleeve seems to have little advantage, whereas stiffness relief of the stem seems to be beneficial. Circumferential porous coating seems the most important factor for durable fixation.

Adult↗
PubMed1996

Contemporary total hip replacement with metal on metal articulation.

Between 1991 and 1994, 74 patients received total hip replacements with metal on metal articulation. The results of these patients with 74 hips who had a 6-month to 4-year (average, 2.2 years average) followup are reported. Patients were prospectively evaluated by the Harris hip score, a patient self assessment form, and radiographs. The average postoperative Harris hip score was 91. Patient self assessment forms showed that 95% of the patients scored their results as excellent or good. No patient had revision for loosening, but 1 underwent revision surgery for recurrent dislocation. Serial radiographs have not revealed loosening or osteolysis. Wear could not be measured radiographically. Twenty-seven of the patients had bilateral total hip replacements with 1 hip being metal on polyethylene; the patients could not detect any difference between the 2 hips. The satisfactory short term results from the contemporary metal on metal articulation investigated in this study are encouraging and warrant continued study.

Adult↗
PubMed1996

Rehabilitation after total knee arthroplasty: a comparison of 2 rehabilitation techniques.

This study was conducted to compare postoperative total knee arthroplasty rehabilitation protocols. The hypothesis of this study was that patients undergoing total knee arthroplasty could achieve range of motion and hospital discharge in the same period using a postoperative rehabilitation protocol that did not use a continuous passive motion machine. This randomized prospective study compared 46 total knee arthroplasties in which a continuous passive motion machine was used with 37 total knees that were rehabilitated with early passive flexion of the knee (named drop and dangle protocol). Postoperative physical therapy regimens were otherwise the same for both groups. Surgical technique was the same for both groups except for closure which was performed in the drop and dangle group with the knee at 90 degrees to 95 degrees flexion. Only patients with osteoarthritis were included in the study, and in both groups of patients received the same prosthetic components. Patients in the drop and dangle group were discharged from the hospital 1 day earlier (p = 0.01) and had a statistically better extension range of 2.8 degrees at 6 months (p = 0.03). Knees in the drop and dangle group had less drainage (p = 0.06). Range of motion and hospital discharge can be achieved in a similar time interval with the drop and dangle technique as with using a continuous passive motion device, and that such a device is not required for postoperative knee rehabilitation.

Adult↗
PubMed1996

Modern metal on metal articulation for total hip replacements.

Between 1991 and 1994, 70 patients received total hip replacements with metal on metal articulation. The results of 54 of these patients with 54 hips who have a 2- to 4-year (2.7-year average) followup are reported. Patients were prospectively evaluated using the Harris hip score, a patient self assessment form, and radiographs. Hip aspiration was performed preoperatively and 6 to 24 months postoperatively in 24 hips with metal on metal articulations. Implant retrieval was obtained from 2 patients. Harris hip score averages increased from 49 to 93. No patient had revision surgery for loosening, but 1 had revision surgery for dislocation. Patient self assessment forms showed 51 of 54 patients scored their results as good or excellent. Serial radiographs did not show loosening or osteolysis. Wear could not be measured radiographically. Synovial fluid samples had metal particles of 1 to 10 microm in 10 hips. Twenty patients had bilateral total hip replacements with 1 hip metal on polyethylene articulation, and patients could not determine any difference between the hips. Compared with historic results of previous metal on metal prostheses, the modern metal on metal articulation investigated in this study did not have early acetabular loosening or clinical symptoms of component impaction. Retrieval implants and synovial fluid analysis suggest early wear was minimal.

Adult↗
PubMed1995

Indications for bilateral total knee replacement.

A total of 64 patients with clinical and radiographic signs of bilateral knee arthritis were evaluated based on multiple associated variables including complications, community ambulatory levels, and timing of staged knee replacement. A pain/dysfunction categorization based on initial presentation was established so that temporal progression of symptoms could be documented. Two surgical groups were represented: simultaneous bilateral total knee replacement and staged bilateral knee replacement. The findings in this study indicate that a patient with equally painful knees should undergo simultaneous bilateral total knee arthroplasty. If a patient has bilateral disease but only one knee is symptomatic, surgery should be performed on only the painful knee. If both knees are symptomatic, but one knee is much more painful than the other, the choice of treatment must be individualized based on the patient's medical health, symptoms, type of fixation used, and Charnley activity classification.

Aged↗
PubMed1995

Muscle flaps in total knee arthroplasty.

The results of 12 patients who had been treated with muscle flap coverage for compromised soft tissues associated with total knee arthroplasty were studied. Five latissimus dorsi free flaps, 6 medial gastrocnemius rotational flaps, and 2 rectus abdominis free flaps were done in 12 knees. The authors used and classified 3 types of muscle flaps: (1) prophylactic soft tissue coverage, done before definitive reconstruction; (2) treating muscle flap for infected prostheses with deficient soft tissue coverage; and (3) salvage muscle flap for wound dehiscence or necrosis in the immediate postoperative period. These patients were observed for an average of 4.1 years (range, 1-8 years). The wound was revascularized successfully in 100% of the knees. The prosthesis was preserved in 83% of the knees. Recurrent infection occurred in 3 patients. Treating muscle flaps are least likely to result in an overall successful reconstruction because these flaps are used in knees with chronic infection. Prophylactic flaps and salvage muscle flaps provide the soft tissue coverage necessary to allow successful reconstruction in the appropriate circumstances.

Adult↗
PubMed1995

Ten years of experience with porous acetabular components for revision surgery.

A prospective study was completed for 139 porous-coated revision acetabular components that were implanted with rim fit fixation and had a mean of 4.3 years' followup (range, 2-9.8 years). The Anatomic Porous Replacement component was studied. Harris Hip Scores were used for clinical evaluation, and the pain and limp components of the Harris Hip Score were assessed. Radiographic measurements were recorded as radiolucent lines by Delee and Charnley zones. Clinical results were of lesser value in this study because of the emphasis on the acetabular component. Of these components, 4.3% had revision; only 2 (1.4%) were revised for loosening. Migration occurred in 2.1% of these acetabular components. In the first 2 years postoperatively, 17.4% of components had increased radiolucent lines and 9.4% had fewer radiolucent lines. After 2 years, fixation was stable: 4% had progressively more radiolucent lines and 2% fewer radiolucent lines. The authors could not show any statistical difference in radiographic fixation of these components when adjunctive screw fixation was used or not used. Fixation of the acetabular components was better when slurry bone graft was not used to layer the acetabular surface. Fixation was similar whether the rim fit was obtained with or without protrusion of the medial dome of the cup into the pelvis. The authors did not observe osteolysis in the acetabular bone surrounding these components.

Acetabulum↗
PubMed1995

Hydroxyapatite-coated proximal ingrowth femoral stems. A matched pair control study.

A matched pair study of 2 groups of 42 uncemented total hip replacements were compared retrospectively after a minimum 3-year followup. Forty-two hips were implanted with a hydroxyapatite coating on the proximal femoral patched porous surfaces; 42 hips had patched porous-coated stems without hydroxyapatite. There were no clinical differences between the matched groups by any criteria of measurement. There was no statistically significant difference between the matched groups for femoral stem fixation at all followup intervals. At the 3-year followup, 90% of the femoral stems in the hydroxyapatite porous group, and 83% in the porous control group achieved stable bony fixation. Hydroxyapatite-coated femoral stems demonstrated accelerated bone remodeling characterized by proximal cancellous hypertrophy. The percentage of femoral stems exhibiting cancellous hypertrophy was significantly greater at all followup intervals. This study did not demonstrate any clinical advantage of hydroxyapatite being added to a porous-coated surface. The radiographic changes of bone remodeling seen with hydroxyapatite are not known to improve durability of the hip arthroplasty. This study again condemns the use of patched porous-coating and titanium-bearing surfaces.

Adult↗
PubMed1995

Management of civilian gunshot injuries to the hip.

The orthopedic surgeon at a civilian trauma center is likely to encounter a gunshot injury to the hip. The nonmilitary literature regarding this injury gives few guidelines regarding an appropriate diagnostic evaluation or the indication for arthrotomy. We found that the best diagnostic test to detect joint penetration was hip aspiration followed by an arthrogram. Selected cases can be treated successfully with antibiotic therapy without an arthrotomy. These cases involve a low-velocity missile that passes through the joint, causes minimal bone disruption, and is free of bowel contaminants. If an arthrotomy is not performed, the physician must follow the patient with repeated physical examinations, complete blood counts, and a hip aspiration whenever infection is suspected. All transbdominal hip injuries require an immediate arthrotomy. In this series, bullets left in contact with joint fluid resulted in joint destruction or infection. Each patient with a displaced femoral neck fracture had a poor outcome with internal fixation. Hip arthroplasty or fusion should be considered as elective procedures for definitive management of these injuries.

Algorithms↗