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Biomedical subjects

Wayne G Paprosky

Publications and source records attributed to Wayne G Paprosky.

At least 19 recordsLinked to original sources
PubMed2006

Stem diameter and rotational stability in revision total hip arthroplasty: a biomechanical analysis.

BACKGROUND: Proximal femoral bone loss during revision hip arthroplasty often requires bypassing the deficient metaphyseal bone to obtain distal fixation. The purpose of this study was to determine the effect of stem diameter and length of diaphyseal contact in achieving rotational stability in revision total hip arthroplasty. METHODS: Twenty-four cadaveric femoral specimens were implanted with a fully porous-coated stem. Two different diameters were tested and the stems were implanted at multiple contact lengths without proximal bone support. Each specimen underwent torsional testing to failure and rotational micromotion was measured at the implant-bone interface. RESULTS: The larger stem diameter demonstrated a greater torsional stability for a given length of cortical contact (p <or= 0.05). Decreasing length of diaphyseal contact length was associated with less torsional stability. Torsional resistance was inconsistent at 2 cm of depth. CONCLUSION: Larger stem diameters frequently used in revisions may be associated with less diaphyseal contact length to achieve equivalent rotational stability compared to smaller diameter stems. Furthermore, a minimum of 3 cm or 4 cm of diaphyseal contact with a porous-coated stem should be achieved in proximal femoral bone deficiency and will likely be dependent on the stem diameter utilized at the time of surgery.

Journal Article↗
PubMed2006

Constrained liners in revision total hip arthroplasty: an overuse syndrome: in the affirmative.

Instability after primary and revision total hip arthroplasty continues to be problematic for the surgeon. The use of constrained liners, which use a locking mechanism to capture the femoral head, has increased to help manage this problem. Constrained liners, however, present problems with acetabular component loosening, dissociation of the liner/shell interface, failure by breakage, and excessive polyethylene wear. Rather than resort to constrained liners, our approach has been to restore joint stability with large-diameter femoral heads. The advantages are increased range of motion due to more favorable head/neck ratio, increased resistance to dislocation due to increased jump distance, and the avoidance of skirted femoral heads. With the addition of cross-linked polyethylene, the volumetric wear associated with large heads is much decreased and makes this a viable option today.

Adult↗
PubMed2006

The use of a trabecular metal acetabular component and trabecular metal augment for severe acetabular defects.

Stable acetabular fixation cannot be reliably achieved with the use of a hemispherical porous coated component alone in patients with a Paprosky type IIIa defect. The purpose of the present study was to determine the short-term results of a tantalum porous coated hemispherical acetabular component supported with a modular tantalum augment in Paprosky type IIIa defects. A total of 28 patients (28 hips) were treated for a type IIIa acetabular defect between 2001 and 2003 with the use of a trabecular metal acetabular component supported with a modular, superiorly placed trabecular metal augment. At an average of 3.1 years follow-up, 1 patient required rerevision for recurrent instability. The remaining hips remain radiographically stable. Clinically, the patients' modified Postel Merle d'Aubigne score improved from 6.8 preoperatively to 10.6 postoperatively. The use of a trabecular metal acetabular component with a superiorly placed trabecular metal augment demonstrates encouraging short-term results for Paprosky type IIIa acetabular defects.

Acetabulum↗
PubMed2006

Acetabular revision using a trabecular metal acetabular component for severe acetabular bone loss associated with a pelvic discontinuity.

Pelvic discontinuity can be encountered during acetabular revision in patients with severe bone loss. All patients who had an acetabular reconstruction for a type IIIB acetabular defect according to the classification of Paprosky et al [Paprosky WG, Perona PG, Lawrence JM. 1994. Acetabular defect classification and surgical reconstruction in revision arthroplasty. A 6-year follow-up evaluation. J Arthroplasty 9:33.] with an associated pelvic discontinuity between 2001 and 2003 were reviewed. A trabecular metal acetabular component with or that without an acetabular augment was used to obtain fixation proximal and distal to the discontinuity. Thirteen patients (13 hips) were treated for a type IIIB acetabular defect. At an average of 2.6 years of follow-up, 1 patient demonstrated possible radiographic loosening. The other 12 patients maintained radiographically stable hips. None of the patients required repeat surgical intervention. Clinically, the patients' modified Postel-Merle d'Aubigne score improved from 6.1 preoperatively to 10.3 postoperatively. The treatment of pelvic discontinuity during acetabular revision using a trabecular metal acetabular component with or that without an associated trabecular metal augment appears to provide reliable and reproducible short-term results.

Acetabulum↗
PubMed2006

Porous-ingrowth revision acetabular implants secured with peripheral screws. A minimum twelve-year follow-up.

BACKGROUND: During revision total hip arthroplasty, the acetabular component is often secured with screws to ensure initial press-fit stability. The purpose of the present study was to assess a series of acetabular revisions involving the use of a porous-coated acetabular component that was stabilized with peripheral screws and to evaluate the results in relation to the acetabular bone deficiencies that were present at the time of the revision procedure. METHODS: From 1987 to 1991, 203 consecutive acetabular revisions were performed. In 142 hips, a severe acetabular bone deficiency that did not require an allograft was reconstructed with a porous-coated acetabular cup that was secured with a minimum of two peripheral screws. After an average duration of follow-up of 13.2 years, 134 hips were reviewed clinically and radiographically. The procedure was considered to be a clinical failure if the component was revised or if the postoperative clinical scores were poorer than the preoperative scores. RESULTS: At the time of the most recent follow-up, 127 (95%) of the 134 hips were stable and clinically successful. The other seven hips (5%) were considered to have failed. Five of these seven hips failed because of an infection, and two failed because of aseptic loosening. Five (19%) of the twenty-seven hips with a Paprosky type-3A defect (a defect in which 30% to 50% of the host acetabulum is missing) failed. CONCLUSIONS: Revision total hip arthroplasty with use of a porous-coated acetabular component that is fixed with peripheral screws can provide long-term durability in hips with severe acetabular defects that do not require the use of an allograft (Paprosky type-1 and type-2 defects). We recommend that when an acetabular implant with peripheral screws is used for the treatment of a more severe (type-3) defect, the cup should be augmented with structural allograft to improve initial stability, or other implants should be utilized.

Acetabulum↗
PubMed2006

The use of structural distal femoral allografts for acetabular reconstruction. Surgical technique.

BACKGROUND: Acetabular fixation during revision total hip arthroplasty in patients who have a nonsupportive superior dome and proximal migration of the acetabular component (a Paprosky Type-IIIa defect) cannot be achieved reliably with use of a hemispherical porouscoated component alone. The purposes of the present study were to determine the long-term results associated with the use of a porous-coated hemispherical acetabular component, supported with a distal femoral structural allograft, for revision at the site of a Type-IIIa defect and to determine if graft resorption leads to late failure. METHODS: Thirty-one patients who had an acetabular reconstruction with use of a distal femoral allograft for the treatment of a Type-IIIa defect between January 1985 and December 1990 were followed annually with clinical and radiographic evaluations. At the time of the latest follow-up, eight patients had died and one patient had been lost to follow-up. One of the patients who died had had a clinical failure at 4.5 years postoperatively and was included in the analysis. Therefore, twenty-three patients, who had had an average age of sixty-one years at the time of the index procedure, were evaluated at an average of 10.3 years postoperatively. RESULTS: Five acetabular components were re-revised because of aseptic loosening at an average of 5.3 years after the index procedure. Radiographically, all but one of the remaining components were stable and showed evidence of bone ingrowth. The average Merle D'Aubigné and Postel hip score improved from 5 points preoperatively to 10 points at the time of the latest follow-up. Allograft bone resorption, although difficult to quantitate, was observed around six of the seventeen stable components and around two of the five components that failed clinically. CONCLUSIONS: Acetabular revision with use of a porous-coated acetabular component along with a structural distal femoral allograft for the treatment of a Type-IIIa defect demonstrated a high rate of clinical and radiographic success after an average of ten years of follow-up.

Acetabulum↗
PubMed2006

Managing bone loss in acetabular revision.

The management of bone loss encountered during acetabular revision remains challenging. In order to obtain a successful surgical result, preoperative planning is required to estimate the severity and location of bone defects. Most acetabular revisions can be treated with the use of a cementless hemispherical component. However, a successful surgical reconstruction requires component stability. Depending on the degree of bone loss, the surgical reconstruction may require the use of cancellous or structural bone graft, acetabular augmentation, an acetabular cage, a custom implant, or an acetabular transplant.

Acetabulum↗
PubMed2005

The treatment of pelvic discontinuity during acetabular revision.

Pelvic discontinuity is frequently encountered during acetabular revision in patients with severe acetabular bone loss. Prompt recognition of the discontinuity and appropriate intraoperative management are essential for a successful clinical outcome. The treatment of the discontinuity is dependent upon the remaining host bone, the potential for healing of the discontinuity, and the potential for biologic ingrowth of acetabular components. If healing potential of the discontinuity exists, the discontinuity should be treated in compression with a posterior column plate and structural allograft or with the use of trabecular metal acting as an internal plate. If healing potential for the discontinuity does not exist, the discontinuity can be bridged and treated in distraction with either an acetabular transplant supported with a cage or with the use of a custom Triflange implant. However, the poor clinical results observed with either of these treatment modalities for a type IIIB defect with an associated pelvic discontinuity have prompted the senior author to explore the use of a trabecular metal acetabular component with 1 or 2 augments in the majority of his current type IIIB cases. The long-term clinical results of this treatment remain unknown.

Acetabulum↗
PubMed2005

What would you do? Case challenges in hip surgery.

Evaluation and management of 4 challenging hip case scenarios were discussed in an interactive session with a moderator and 5 experts in hip reconstruction. Case-based discussion included total hip arthroplasty for posttraumatic arthritis after acetabular fracture, total hip arthroplasty after failed intertrochanteric hip fracture, total hip arthroplasty for hip dysplasia, and total hip arthroplasty in the case of proximal femoral deformity.

Acetabulum↗
PubMed2005

High failure rate of a constrained acetabular liner in revision total hip arthroplasty.

Fifty-five consecutive revision total hip arthroplasties (THAs) in 51 patients in which a constrained acetabular liner was used (Duraloc Constrained Liner, DePuy, Warsaw, Ind) were reviewed. In these revisions, 41 constrained liners were placed for recurrent instability and 14 for inadequate stability at the time of revision THA. The mean age of the cohort was 62 years, and 38 of the hips were in female patients (69%). At a minimum of 2 years, 9 of the 55 hips (16%) dislocated. Of these 9 dislocations, 8 occurred in patients who had undergone revision to a constrained liner for recurrent instability without femoral or acetabular component revision. Revision THA for recurrent instability by placing a constrained liner without optimizing other aspects of the reconstruction leads to a high rate of recurrent failure.

Acetabulum↗
PubMed2005

Biologic fixation and bone ingrowth.

Total hip arthroplasty has provided thousands of patients with pain relief and has improved their quality of life. Advances in orthopaedic surgical techniques and implant biomaterials now allow predictable surgical results in most patients. Despite the overwhelming success of this surgical procedure, the debate continues surrounding the optimal choice of implants. Femoral and acetabular implants with varying geometries and fixation methods are currently available. Acrylic bone cement has been used extensively in the past for acetabular and femoral fixation. This mode of component fixation currently remains the technique used most frequently throughout Europe and has shown excellent long-term results. Problems inherent with acrylic bone cement, however, have encouraged other surgeons to use alternative surfaces to allow biologic fixation.

Arthroplasty, Replacement, Hip↗
PubMed2005

The treatment of acetabular bone defects with an associated pelvic discontinuity.

UNLABELLED: Pelvic discontinuity is encountered frequently during acetabular revision in patients with severe acetabular bone loss. Prompt recognition of the discontinuity and appropriate intraoperative treatment are essential for a successful clinical outcome. The treatment of the discontinuity is dependent on the remaining host bone, the potential for healing of the discontinuity, and the potential for biologic ingrowth of acetabular components. If healing potential of the discontinuity exists, the discontinuity should be treated in compression with a posterior column plate and structural allograft or with the use of trabecular metal acting as an internal plate. If healing potential for the discontinuity does not exist, the discontinuity should be bridged and treated in distraction with an acetabular transplant supported with a cage, a trabecular metal component with trabecular metal augmentation, or with the use of a custom triflange implant. LEVEL OF EVIDENCE: Therapeutic study, Level III-1 (case-control study). See the Guidelines for Authors for a complete description of levels of evidence.

Acetabulum↗
PubMed2005

The use of structural distal femoral allografts for acetabular reconstruction. Average ten-year follow-up.

BACKGROUND: Acetabular fixation during revision total hip arthroplasty in patients who have a nonsupportive superior dome and proximal migration of the acetabular component (a Paprosky Type-IIIa defect) cannot be achieved reliably with use of a hemispherical porous-coated component alone. The purposes of the present study were to determine the long-term results associated with the use of a porous-coated hemispherical acetabular component, supported with a distal femoral structural allograft, for revision at the site of a Type-IIIa defect and to determine if graft resorption leads to late failure. METHODS: Thirty-one patients who had an acetabular reconstruction with use of a distal femoral allograft for the treatment of a Type-IIIa defect between January 1985 and December 1990 were followed annually with clinical and radiographic evaluations. At the time of the latest follow-up, eight patients had died and one patient had been lost to follow-up. One of the patients who died had had a clinical failure at 4.5 years postoperatively and was included in the analysis. Therefore, twenty-three patients, who had had an average age of sixty-one years at the time of the index procedure, were evaluated at an average of 10.3 years postoperatively. RESULTS: Five acetabular components were re-revised because of aseptic loosening at an average of 5.3 years after the index procedure. Radiographically, all but one of the remaining components were stable and showed evidence of bone ingrowth. The average Merle D'Aubigné and Postel hip score improved from 5 points preoperatively to 10 points at the time of the latest follow-up. Allograft bone resorption, although difficult to quantitate, was observed around six of the seventeen stable components and around two of the five components that failed clinically. CONCLUSIONS: Acetabular revision with use of a porous-coated acetabular component along with a structural distal femoral allograft for the treatment of a Type-IIIa defect demonstrated a high rate of clinical and radiographic success after an average of ten years of follow-up.

Acetabulum↗
PubMed2005

Extensor mechanism allograft reconstruction after total knee arthroplasty.

BACKGROUND: Disruption of the extensor mechanism is an uncommon but catastrophic complication of total knee arthroplasty. We evaluated two techniques of reconstructing a disrupted extensor mechanism with the use of an extensor mechanism allograft in revision total knee arthroplasty. METHODS: Twenty consecutive reconstructions with the use of an extensor mechanism allograft consisting of the tibial tubercle, patellar tendon, patella, and quadriceps tendon were performed. The first seven reconstructions (Group I) were done with the allograft minimally tensioned. The thirteen subsequent procedures (Group II) were performed with the allograft tightly tensioned in full extension. All surviving allografts were evaluated clinically and radiographically after a minimum duration of follow-up of twenty-four months. RESULTS: All of the reconstructions in Group I were clinical failures, with an average postoperative extensor lag of 59 degrees (range, 40 degrees to 80 degrees ) and an average postoperative Hospital for Special Surgery knee score of 52 points. All thirteen reconstructions in Group II were clinical successes, with an average postoperative extensor lag of 4.3 degrees (range, 0 degrees to 15 degrees ) (p < 0.0001) and an average Hospital for Special Surgery score of 88 points. Postoperative flexion did not differ significantly between Group I (average, 108 degrees ) and Group II (average, 104 degrees ) (p = 0.549). CONCLUSIONS: The results of reconstruction with an extensor mechanism allograft after total knee arthroplasty depend on the initial tensioning of the allograft. Loosely tensioned allografts result in a persistent extension lag and clinical failure. Allografts that are tightly tensioned in full extension can restore active knee extension and result in clinical success. On the basis of the number of knees that we studied, there was no significant loss of flexion. Use of an extensor mechanism graft for the treatment of a failure of the extensor mechanism will be successful only if the graft is initially tensioned tightly in full extension.

Arthroplasty, Replacement, Knee↗
PubMed2005

Posterior approach: back door in.

Minimally invasive THA is a controversial topic in adult reconstruction. While early reports championed this new technique for faster return of function, decreased hospital stay, and less pain, these findings are being questioned. More recent reports have highlighted increased complication rates during the surgeon's learning curve and noted a lack of benefit compared with a standard incision. This article describes the senior author's technique for a minimally invasive posterior approach and emphasizes the importance of patient selection and a team approach. The size of the incision should never dictate the quality of the THA nor place the long-term results at risk. Incision length and degree of visualization are dictated by the needs of the specific surgeon as well as the patient's morphology. In appropriate patients, using a team approach and the described minimally invasive posterior approach can lead to a shortened hospital stay and rapid functional recovery without increasing the risk of complications.

Adult↗
PubMed2005

Extensively coated cementless femoral components in revision total hip arthoplasty: an update.

The vast majority of femoral revisions that an orthopaedic surgeon encounters can be treated successfully with an extensively porous coated stem. Long-term results have demonstrated that this type of implant can provide reliable initial fixation with a high propensity for long-term fixation. Depending on the degree of femoral bone loss (Paprosky Type IIIA or Type IIIB bone), a longer cementless stem may be required to obtain initial axial and rotational stability. If severe bone loss is present (Paprosky Type IV bone), large canal diameters are encountered (>19 mm), or if torsion remodeling of the proximal femur has occurred, alternative methods of fixation may be required.

Arthroplasty, Replacement, Hip↗
PubMed2004

The femur in revision total hip arthroplasty evaluation and classification.

Femoral revision total hip arthroplasty is a technically demanding procedure. In addition to these technical issues, preoperative planning can be challenging and with multiple reconstructive options available, the decision-making process can be complex. The ability to preoperatively determine the most appropriate option for reconstruction greatly assists with ensuring that the appropriate implants and instruments are available at the time of surgery. A classification of femoral bone loss is presented that guides the surgeon in selecting an appropriate method of reconstruction.

Arthroplasty, Replacement, Hip↗