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Biomedical subjects

Christopher L Peters

Publications and source records attributed to Christopher L Peters.

17 recordsLinked to original sources
PubMed2006

Biological effects of calcium sulfate as a bone graft substitute in ovine metaphyseal defects.

Calcium sulfate has been used as a bone graft substitute in many fields, from dentistry to orthopedics. However, the results of many studies have yielded inconclusive results. In the present study, a sheep model was used with tibial and femoral metaphyseal defects to determine whether calcium sulfate was as effective as autograft and allograft in promoting new bone formation in a critical size defect. Medical-grade calcium sulfate pellets, autograft bone, allograft bone, or nothing was used to fill the metaphyseal defects. The sheep were allowed to heal for 12 weeks. Sagittal sections from the bones were analyzed with high-resolution contact radiographs, backscattered electron microscopy, and light microscopy. The volume fractions of bone within the defect perimeter were determined, and the histologic quality of the bone was observed. The volume fraction of new bone in the autograft, calcium sulfate, and allograft were not statistically different, but all were significantly different than the untreated control. The majority of the calcium sulfate had been resorbed at 12 weeks, and the histologic quality of the bone appeared similar to the autograft-treated bone. Calcium sulfate appears to be a useful biocompatible bone graft substitute that yields results similar to autograft bone in sheep metaphyseal defects.

Animals↗
PubMed2006

Intramedullary total femoral replacement for salvage of the compromised femur associated with hip and knee arthroplasty.

Severely compromised femora because of prosthetic loosening, osteolysis, or periprosthetic fracture around total hip and knee arthroplasties are increasing. Two approaches that create an intramedullary total femoral (IMTF) replacement are reported. Twenty-three IMTF replacements in 22 patients were performed at 2 institutions. Seven revision total knee arthroplasties with a stemmed component were linked to a well-fixed hip stem with a custom intramedullary sleeve. Sixteen IMTF replacements involved revision of both hip and knee arthroplasties which were connected via an intercalary segment with morse taper junctions. Follow-up averaged 36 months. Complications included 2 dislocations, 2 deep infections, and 2 knee revisions for tibial loosening. Advantages over conventional total femoral replacement or ORIF include less dissection, maintenance of soft tissue attachments, and immediate component stability to allow for early mobilization.

Aged↗
PubMed2006

Early aseptic loosening of a total knee arthroplasty due to Gore-Tex particle-induced osteolysis.

Anterior cruciate ligament reconstruction with the use of synthetic graft material has been used as an alternative to biologic grafts. The use of these grafts has largely been abandoned in reconstruction of the anterior cruciate ligament because of mechanical failure of the graft and production of wear debris leading to synovitis and recurrent effusions. This article presents a case of early, extensive periprosthetic osteolysis around a total knee arthroplasty associated with wear debris from retained fragments of a Gore-Tex (WL Gore and associates, Inc, Flagstaff, Ariz) (polytetrafluoroethylene) anterior cruciate ligament graft.

Aged↗
PubMed2006

Mechanical bond strength of the cement-tibial component interface in total knee arthroplasty.

The purpose of this study was to mechanically test the cement-tibial component interface using titanium and cobalt-chrome sample prostheses with several commercially available surface textures. The results of this study indicate that the type of metal substrate and surface preparation of contemporary tibial baseplates may influence the strength of the metal-cement interface and as such influence tibial component survival. The results indicate that, in general, metal-cement interface strength increases with increasing surface roughness and common surface treatments such as AlO2 grit-blasting (Ra = 6.76 microm) produce interface strengths similar to plasma-spray, porous-coated specimens. Macrosurfaced tibial components, although comparable in tension, may be vulnerable to metal-cement interface failure with rotational loading.

Analysis of Variance↗
PubMed2006

The effect of a new multimodal perioperative anesthetic regimen on postoperative pain, side effects, rehabilitation, and length of hospital stay after total joint arthroplasty.

This study evaluated the effect of a new multimodal perioperative anesthetic and pain management strategy for primary total hip (THA) and total knee arthroplasty (TKA). Two cohorts of 50 consecutive THA and 50 TKA patients from before and after initiation of the new protocol were compared. The protocol involved scheduled oral narcotics, cyclooxygenase-2 inhibitors, no intrathecal narcotics, femoral nerve catheters for TKAs, and local anesthetic wound infiltration. Use of patient-controlled analgesia was discouraged. Physical therapy was attempted on the day of surgery. The demographic data, surgical procedure, and implants were similar. There were statistically significant improvements after the protocol regarding rest-pain scores post-operative day (POD) 1 and 2, total narcotic consumption, distance walked POD 1 and 2, and length of stay. There were no significant differences in complications. Implementation of this new multimodal perioperative protocol combined with early mobilization for TKA and THA patients has shortened length of stay, improved pain control, and accomplished therapy goals sooner with less narcotic consumption.

Anesthesia, Epidural↗
PubMed2006

Treatment of femoro-acetabular impingement with surgical dislocation and débridement in young adults.

BACKGROUND: Femoro-acetabular impingement has been associated with acetabular labral and/or articular cartilage damage that may ultimately result in osteoarthritis of the hip. Surgical treatment of femoro-acetabular impingement is directed at restoring a more normal femoral head-neck offset to alleviate femoral abutment against the acetabular rim and treating associated labral and articular cartilage damage. METHODS: Thirty hips with femoro-acetabular impingement (in twenty-nine patients) underwent débridement through a greater trochanteric flip osteotomy and anterior dislocation of the femoral head. There were sixteen male patients and thirteen female patients with a mean age of thirty-one years. Cam (femoral based) impingement was noted in fourteen hips; pincer (acetabular based) impingement, in one hip; and combined cam and pincer impingement, in fifteen hips. The mean duration of clinical and radiographic follow-up was thirty-two months. All patients were followed according to a prospective protocol, with Harris hip scores and plain radiographs obtained preoperatively and at six months, one year, and annually for a minimum of two years. RESULTS: The mean Harris hip score improved from 70 points preoperatively to 87 points at the time of final follow-up (p < 0.0001). Osteonecrosis did not develop in any hip, and there were no trochanteric nonunions. In eighteen hips, severe damage of the acetabular articular cartilage that had not been appreciated on preoperative plain radiographs or magnetic resonance arthrography was noted on arthrotomy. Eight of these eighteen hips subsequently had radiographic evidence of progression of the osteoarthritis, and four of the eight hips required or were expected to soon require conversion to a total hip arthroplasty to treat progressive pain. CONCLUSIONS: At the time of early follow-up, we found that surgical dislocation and débridement of the hip for the treatment of femoro-acetabular impingement in hips without substantial damage to the articular cartilage can reduce pain and improve function. This procedure has a low rate of complications. Radiographic signs of progression of osteoarthritis and clinical failure requiring conversion to a total hip arthroplasty were seen only in patients with severe damage to the acetabular articular cartilage, a finding that emphasizes the need for better imaging methods to assess the extent of damage to the acetabular articular cartilage in patients with this disorder.

Acetabulum↗
PubMed2006

Early results of the Bernese periacetabular osteotomy: the learning curve at an academic medical center.

BACKGROUND: Most reports on the results of the Bernese periacetabular osteotomy for the treatment of developmental dysplasia of the hip have been by the originators of the procedure. In 1997, we began to use this osteotomy without direct training from the originators of the procedure. METHODS: Seventy-three patients (eighty-three hips) underwent a Bernese periacetabular osteotomy between 1997 and 2003 and were followed prospectively with use of the Harris hip score to assess clinical results and with use of anteroposterior pelvic and false-profile lateral plain radiographs to assess radiographic results. The three-dimensional position of the acetabulum was recorded preoperatively and postoperatively. The mean duration of follow-up was forty-six months. RESULTS: The average Harris hip score improved from 54 to 87 points (p < 0.001). Three hips (three patients) had a conversion to total hip arthroplasty at two, three, and four years after the periacetabular osteotomy. Preoperatively, fifty-four of the eighty-three acetabula were anteverted, and twenty-nine were either retroverted or had neutral wall relationships. Postoperatively, sixty-five hips (78%) were anteverted. Radiographically, in preoperatively anteverted hips, the average center-edge angle improved from 3 degrees to 29 degrees (p < 0.0001), the average anterior center-edge angle improved from 5 degrees to 31 degrees (p < 0.0001), and the acetabular index improved from 25 degrees to 5 degrees (p < 0.0001). In preoperatively retroverted or neutral hips, the average center-edge angle improved from 13 degrees to 33 degrees (p < 0.0001), the average anterior center-edge angle improved from 15 degrees to 36 degrees (p < 0.0001), and the acetabular index improved from 19 degrees to 2 degrees (p < 0.0001). Complications included four hematomas, three transient femoral nerve palsies, two deep wound infections, and one transient sciatic nerve palsy. Nine of the ten major complications and all four of the failed osteotomies occurred in the first thirty hips in which the index procedure was performed. CONCLUSIONS: In our experience, the early results of the Bernese periacetabular osteotomy have been encouraging, with a 92% survival rate at thirty-six months. The occurrence of complications demonstrates a substantial learning curve. Recognition of the true preoperative acetabular version and reorientation of the acetabulum into an appropriately anteverted position have become important factors in surgical decision-making. LEVEL OF EVIDENCE: Therapeutic Level IV.

Acetabulum↗
PubMed2006

Soft-tissue balancing in primary total knee arthroplasty.

The surgical goal of primary total knee arthroplasty (TKA) is to provide a well-balanced soft-tissue envelope surrounding a well-aligned, well-fixed implant. Some knee surgeons have emphasized that a good outcome in primary TKA is more dependent on soft-tissue management than bone management. Thus, it is imperative that the surgeon is familiar with knee soft-tissue balancing techniques to address the varus, valgus, and associated flexion contracture deformities commonly encountered in primary TKA.

Arthroplasty, Replacement, Knee↗
PubMed2005

Revision total knee arthroplasty with modular components inserted with metaphyseal cement and stems without cement.

The clinical and radiographic outcomes of 50 consecutive revision total knee arthroplasties in 47 patients, placed with metaphyseal cemented femoral and tibial components with press-fit cementless stems, were reviewed at 36-month average follow-up. Revision was performed for aseptic loosening (11/50), infection (17/50), periprosthetic fracture (8/50), component failure (6/50), instability (6/50), and malalignment (2/50). The press-fit cementless stems were 80 to 160 mm in length and tightly contacted the endosteum of the metadiaphyseal areas. Four (9%) knees were re-revised for infection, zero for aseptic loosening. The average modified Hospital for Special Surgery knee score improved from 49 to 87. One patient (2%) reported thigh pain, and 1 reported leg pain. Metaphyseal cemented revision total knee components with press-fit cementless femoral and tibial stems were not associated with significant thigh and leg pain.

Adult↗
PubMed2005

Subject-specific finite element model of the pelvis: development, validation and sensitivity studies.

A better understanding of the three-dimensional mechanics of the pelvis, at the patient-specific level, may lead to improved treatment modalities. Although finite element (FE) models of the pelvis have been developed, validation by direct comparison with subject-specific strains has not been performed, and previous models used simplifying assumptions regarding geometry and material properties. The objectives of this study were to develop and validate a realistic FE model of the pelvis using subject-specific estimates of bone geometry, location-dependent cortical thickness and trabecular bone elastic modulus, and to assess the sensitivity of FE strain predictions to assumptions regarding cortical bone thickness as well as bone and cartilage material properties. A FE model of a cadaveric pelvis was created using subject-specific computed tomography image data. Acetabular loading was applied to the same pelvis using a prosthetic femoral stem in a fashion that could be easily duplicated in the computational model. Cortical bone strains were monitored with rosette strain gauges in ten locations on the left hemipelvis. FE strain predictions were compared directly with experimental results for validation. Overall, baseline FE predictions were strongly correlated with experimental results (r2=0.824), with a best-fit line that was not statistically different than the line y=x (experimental strains = FE predicted strains). Changes to cortical bone thickness and elastic modulus had the largest effect on cortical bone strains. The FE model was less sensitive to changes in all other parameters. The methods developed and validated in this study will be useful for creating and analyzing patient-specific FE models to better understand the biomechanics of the pelvis.

Aged↗
PubMed2004

Reconstruction of the medial femoral condyle and medial collateral ligament in total knee arthroplasty using tendoachilles allograft with a calcaneal bone block.

Absence or compromise of the medial collateral ligament (MCL) in conjunction with osseous defects of the medial femoral condyle in total knee arthroplasty (TKA) is a challenging reconstructive problem. Treatment usually requires a highly constrained TKA with or without ligamentous reconstruction. To restore the medial femoral condylar bone and to provide ligamentous stability on the medial side of the knee, the authors present a technique for reconstruction of the medial femoral condyle and MCL using a tendoachilles allograft with a calcaneal bone block. The construct also can be augmented with a semitendinosus tendon autograft. Two illustrative cases and a review of the literature are presented.

Achilles Tendon↗
PubMed2004

Acetabular revision with a modular anti-protrusio acetabular component.

Current anti-protrusio cages are non-porous-coated and 1 piece and they require liner cementation. These factors limit bone ingrowth, trials, and modularity. Results of a completely modular porous-coated anti-protrusio component (MAPC) are presented. Sixty-three acetabular revisions with MAPC were performed from 1998-2001 by 2 surgeons. Average follow-up was 29 months (range, 24-50). 30/63 (48%) had Paprosky type 3A or B defects. 55/63 (87%) MAPCs remain in place. Four components were removed for infection, 3 for loosening, and 1 for malposition. Eight hips dislocated, requiring 6 reoperations. Two MAPCs are radiographically loose but asymptomatic. At short-term follow-up, these results are comparable to conventional 1-piece anti-protrusio cages. Advantages include the potential for bone ingrowth and long-term fixation, surgical technique similar to large hemispherical components, ability to trial, and modularity.

Acetabulum↗
PubMed2003

Tibial component fixation with cement: full- versus surface-cementation techniques.

Despite excellent outcomes with cemented tibial components in total knee arthroplasty, it still is debated whether the tibial stem should be cemented and what the optimal tibial stem design should be. Proponents of full cementation of the tibial stem and component state that better short-term and long-term component fixation is achieved when full cementation is used. Advocates for surface cementation contend that sufficient implant stability is achieved without the increased bone loss that occurs at revision and the stress shielding thought to be linked with cemented stems. This biomechanical cadaver study compared initial fixation and cement penetration depth in fully cemented versus surface cemented tibial trays with two different stem geometries (cruciate and I-beam) and compared two stem designs (cruciate and I-beam) fixed with surface cementation. Under an eccentric load, simulating three times body weight for 6000 cycles, there seems to be no difference in the micromotion of either tibial component implanted with surface or full cementation. Additionally, no difference in the average depth of cement penetration was detected between fixation techniques or stem types. The initial fixation stability of the surface cement technique seems correlated to the depth of cement penetration into proximal tibial surface. The current data support other studies which indicate that stability of surface-cemented tibial components may be related to the depth of cement penetration.

Adult↗
PubMed2003

Revision of well-fixed cementless acetabular components for polyethylene failure.

The results of revision of well-fixed Porous Coated Anatomic cementless acetabular components for polyethylene failure or periacetabular osteolysis in 18 hips (14 patients) are reported. Revisions were done with larger diameter cementless acetabular components replacing one-piece Porous Coated Anatomic devices for which no replacement liner was available. The objective was to determine the increase in size of the revision acetabular component and to assess clinical and radiographic outcomes. The Porous Coated Anatomic components were in place for an average of 7.8 years. At an average followup of 68 months, all revision components remain in place. Preoperatively, 12 hips in 10 patients had radiographic osteolysis, and 25 osteolytic lesions in 17 patients were grafted at revision. All grafted lesions showed partial or complete evidence of bone graft consolidation. The average revision component size increased 8.5 mm in diameter (range, 3-14 mm) compared with the primary component size. This corresponded to an average 6.5-mm increase in the acetabular cavitary diameter. When locking mechanism failure in a well-fixed cementless acetabular component prevents polyethylene liner replacement, acetabular component revision can provide good clinical and radiographic results with acceptable bone loss and improved access to osteolytic areas for debridement and grafting.

Acetabulum↗
PubMed2003

Fixation of periprosthetic femur fractures: a biomechanical analysis comparing cortical strut allograft plates and conventional metal plates.

This study compared the stability of periprosthetic femur fractures fixed using cortical allograft struts with a metal plate. Cadaveric specimens were loaded in single-leg stance and stair climbiing to 2250 N. Optimum stability in single-leg stance was achieved with two long struts medially and laterally. No clear advantage was noted in using a second strut in stair climbing. Cables rather than wires were useful in single-leg stance, but not in stair climbing. Allograft cortical struts are a biomechanically sound alternative to metal plates fixed with screws and cables for femur fracture fixation below a well-fixed femoral component.

Biomechanical Phenomena↗
PubMed2002

Locking mechanism failure in the Harris-Galante porous acetabular component associated with recurrent hip dislocation.

In this review of longitudinal studies of the Harris-Galante porous acetabular component, 20% of all revisions were caused by failure of the polyethylene liner locking mechanism. We report 2 cases of locking mechanism failure in the Harris-Galante porous acetabular component presenting with recurrent dislocation. Broken tines from the acetabular locking mechanism were found embedded into the polyethylene liners in both cases. In a 79-year-old woman with recurrent dislocation, the polyethylene liner and femoral head were replaced, and the acetabular component was revised. In a 74-year-old man with chronic recurrent dislocation, the polyethylene liner and femoral head were replaced, but the acetabular component was preserved. Appropriate treatment for locking mechanism failure with a well-fixed acetabular component depends on many factors, and further long-term data are needed.

Acetabulum↗