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J Bohannon Mason

Publications and source records attributed to J Bohannon Mason.

17 recordsLinked to original sources
PubMed2006

Acetabular component deformation with press-fit fixation.

Acetabular component deformation secondary to forces encountered during insertion is a potential consequence of the press-fit technique. This study characterized the stiffness of Pinnacle 100 cups (DePuy, Warsaw, Ind) via mechanical testing and used this information with intraoperative measurements of cup deformation to calculate the in vivo forces acting on cups inserted during hip arthroplasty in 21 patients. We found that 90.5% of cups had measurable compression deformity, averaging 0.16 +/- 0.16 mm. The corresponding forces acting on these cups averaged 414 +/- 421 N. For hard-on-hard bearing surfaces, such in vivo deformation of acetabular shells may result in negative clinical consequences such as equatorial loading with increased wear and potential seizing of components, chipping of ceramic inserts, or locking mechanism damage.

Acetabulum↗
PubMed2006

Removing well-fixed total knee arthroplasty implants.

UNLABELLED: Revision total knee arthroplasty requires the removal of one or all of the prior knee components. Thoughtful and careful removal of well-fixed total knee components can preserve host bone stock and facilitate subsequent reconstructive efforts. The tools and techniques for knee component removal include simple osteotomes, saws, extraction devices, ultrasonic devices, and frequently a combination of some or all of the above. It is the unique nature of each revision arthroplasty, which presents the surgeon with such challenge. Each of the techniques discussed in this review reflects the anecdotal experience acquired in over 800 revision total knee arthroplasties performed at our center. We review our empiric bias regarding the individual applicability of these techniques. LEVEL OF EVIDENCE: Therapeutic studies, Level V (expert opinion). See Guidelines for Authors for a complete description of Levels of Evidence.

Arthroplasty, Replacement, Knee↗
PubMed2006

When computer-assisted knee replacement is the best alternative.

We studied whether computer-assisted surgery could properly align total knee arthroplasty when traditional instrumentation was not possible or appropriate. We identified 16 patients (18 knees) who we believed could not be treated using traditional instrumentation because of posttraumatic femoral deformity, retained femoral hardware, a history of osteomyelitis, or severe cardiopulmonary disease. Computer-assisted surgery was successfully used in 17 knees; we were unable to accurately register the hip in one morbidly obese patient. We judged the overall mechanical axis of the limb using computer-assisted surgery acceptable in 16 of 17 knees. One patient with a major posttraumatic biplane deformity had an overall mechanical axis in 4 degrees of varus. Computer-assisted navigation seemed helpful in difficult situations where accurate alignment remains crucial, yet traditional instrumentation is not applicable.

Arthroplasty, Replacement, Knee↗
PubMed2006

Importance of a balanced-gap technique in rotating-platform knees.

Rotating-platform knees are constructed of highly conforming polyethylene to reduce contact pressures that potentially cause wear. The mobile nature of the rotating platform can lead to bearing spin-out. The purpose of this study was to determine the prevalence of spin-out in a single series. A total of 426 knees in 393 patients were included in the study. All knees were implanted using a balanced-gap technique. The average follow up was 3.2 years. There were no cases of bearing spin-out. The author concludes that the balanced-gap technique reliably prevents spin-out in mobile-bearing total knee implantation. This implantation technique provides the potential wear benefits of the rotating platform design with a nominal bearing spin-out rate.

Adult↗
PubMed2005

Cementless revision total hip arthroplasty without allograft in severe proximal femoral defects.

This study evaluates the difficult reconstructive challenge of severe proximal femoral bone loss. We present intermediate-term results of 46 hips with extensive proximal femoral bone loss that underwent revision total hip arthroplasty using cementless distal fixation without supplemental allograft. All were evaluated with the Harris hip score at a minimum of 2 years. Radiographs were assessed using the Engh fixation scale. At a mean of 6.4 (range 2-12) years, 43 of the 46 prostheses were functioning well. Two patients required revision for symptomatic loosening, and 1 prosthesis remains radiographically loose with a fair clinical score. Mean Harris hip score was 77 at last follow-up. There were 6 intraoperative femur fractures, 9 dislocations, 10 cases of severe stress shielding, and no infections.

Adult↗
PubMed2005

Failure of femoral surface replacement for femoral head avascular necrosis.

The appropriate treatment for the young patient with post-collapse avascular necrosis (AVN) of the femoral head continues to be controversial. Femoral surface replacement (FSR) has emerged as a potential strategy to delay total hip arthroplasty in these patients. Between 1997 and 2003, 37 FSR procedures were performed. Success was defined as patients not requiring revision surgery or having a Harris hip pain score of 30 or greater. Failure was defined as patients having revision surgery or a Harris hip pain score of 20 or less. The overall failure rate based on Harris hip pain scores and revision surgery was 64.8% (24/37 procedures). Fifteen (40.5%) procedures required revision surgery, whereas 9 (24.3%) patients were considered failures based on their pain scores. The purpose of this study was to determine if FSR is a viable option for post-collapse AVN. We conclude that hemiresurfacing for AVN is an unpredictable procedure. This procedure is no longer offered as a treatment option for post-collapse AVN at our institution.

Adolescent↗
PubMed2005

Outcome comparison of partial and full component revision TKA.

UNLABELLED: We compare the clinical and radiographic results of partial-component versus full-component revision total knee arthroplasty. A retrospective review was used to identify patients who had partial revision total knee arthroplasty. Only isolated femoral or tibial revisions were included. From 1986 to 2000, 448 revision total knee arthroplasties were done. Seventy-seven partial revisions were done. Three were excluded for a diagnosis of infection. The average followup was 63 months. The average Knee Society score for full component revisions was 85 compared with 79 for partial revisions. This difference was significant (p = 0.0001). The average Knee Society score for those patients who had a full revision for instability was 85 compared with 63 for partial revision (p = 0.0001). The average Knee Society score for those patients who had a full revision for wear-related problems was 88 compared with 78 for partial revisions (p = 0.03). Although the advantages of partial revision in hip replacement are well-documented, the efficacy of this treatment strategy has not been established in revision total knee arthroplasty. Care should be taken when considering partial revision for instability or wear-related problems. LEVEL OF EVIDENCE: Therapeutic study, Level III (retrospective cohort study). See the Guidelines for Authors for a complete description of levels of evidence.

Arthroplasty, Replacement, Knee↗
PubMed2004

Early morbidity of modular exchange for polyethylene wear and osteolysis.

This study assessed the early morbidity associated with modular component exchange surgery for the treatment of accelerated polyethylene wear and osteolysis in 55 patients. Review of the surgical records revealed no significant intraoperative complications, little intraoperative blood loss (mean 333 mL), no allogenic blood transfusions, and no recorded postoperative deep vein thromboses. Eighteen percent of patients, however, experienced postoperative dislocation. Five patients dislocated multiple times, 3 of which required rerevision surgery. Two patients required rerevision for femoral implant fractures related to osteolysis and 1 additional patient required rerevision due to catastrophic failure of the acetabular component 5 years postoperatively. With an average follow-up of 30 months, 6 of the 55 patients treated with modular exchange required rerevision. The results of this study suggest that instability is the most prevalent early complication associated with modular component exchange. As such, we believe that more stable constructs should be emphasized, possibly at the expense of polyethylene thickness.

Acetabulum↗
PubMed2004

Early osteolysis associated with trunion-liner impingement.

Osteolysis is perhaps the biggest unsolved problem in joint arthroplasty. Many factors contribute to osteolysis, some of which cannot be controlled. It is imperative to minimize controllable factors contributing to osteolysis whenever possible. We report four cases of trunion impingement on an elevated rim liner, which may have contributed to early aggressive osteolysis. Although the use of an elevated liner may result in a lower incidence of postoperative instability, the trade-off in using such a device must be understood.

Adult↗
PubMed2004

Bipolar reconstruction for recurrent instability of the hip.

Between 1986 and 1998, 81 total hip revisions were performed for recurrent instability. Twenty-three revisions were fixed cups to bipolars. Average follow-up was 50 months. Radiographic evaluation showed no significant osteolysis and average migration of 1.7 mm. The average postoperative Harris hip score was 74. All patients who underwent revision to a bipolar prosthesis had no further instability. Acetabular revision to a bipolar prosthesis provides stability in recurrent prosthetic hip instability.

Arthroplasty, Replacement, Hip↗
PubMed2003

The value of white blood cell counts before revision total knee arthroplasty.

A white blood cell count (WBC) of >50000 cell/mm(3) from a knee aspirate with >or=80% polymorphonuclear cells (PMNCs) is suggestive of infection. This study sought to determine if these same criteria were applicable when interpreting aspirates from a total knee. Of 440 revision total knee arthroplasties, 86 patients had preoperative aspirations of the knee before revision. Fifty-five aspirates were from aseptic failures; 31 aspirates were from patients determined to have septic failure. The mean white blood cell (WBC) count in aspirates from the aseptic group was 645 cells/mm(3) (SD = 878). The mean WBC count in the septic group was 25951 cells/mm(3) (SD = 34994; P=<.001). The mean percentage of PMNCs was statistically higher in the septic group compared with the aseptic group (72.8% vs 27.3%; P=<.001). The synovial fluid WBC count differential analysis is a statistically relevant indicator of the presence or absence of infection in revision knee arthroplasty. Aspirates with a WBC count of 2500 per milliliter and 60% PMNCs are highly suggestive of infection.

Arthroplasty, Replacement, Knee↗
PubMed2003

Hip arthroscopy: surgical approach, positioning, and distraction.

The hip is the most deeply recessed joint in the body making it difficult to access arthroscopically. However, for the patient with a symptomatic loose body or labral tear open techniques are less advantageous. It is for this reason that, however difficult, minimally-invasive approaches to the hip have been developed. Meticulous attention to proper positioning and portal placement is paramount for safe and successful arthroscopy of the hip. The current authors will review the seminal features of positioning and minimally-invasive surgical approaches to the hip.

Arthroscopy↗
PubMed2003

Stem fixation in revision total knee arthroplasty: a comparative analysis.

Methods of stem fixation are a controversial aspect of revision TKA. We sought to determine which technique was superior by reviewing 475 revision TKAs done between 1986 and 2000. Of these 475 revisions, 286 major component revisions were done using 484 extended stems for fixation. Patients who died, patients who had less than 2 years follow up, or patients who had diaphyseal engaging stems were excluded from the study. The final data set included 113 revision TKAs with 202 metaphyseal engaging stems. Of the 202 stems, 107 were cemented whereas 95 were press-fit metaphyseal engaging stems. One hundred one of these were femoral stems and 101 were tibial stems. Using a modified Knee Society radiographic scoring system, 100 (93%) of the 107 implants with cemented stems were considered stable, seven (7%) were categorized as possibly loose requiring close followup, and none were loose. Of the 95 implants placed with cementless stems, only 67 (71%) were categorized as stable. Eighteen (19%) were possibly loose requiring close followup and 10 (10%) were loose (two tibial and eight femoral implants). We currently would urge caution in using cementless metaphyseal engaging stems for fixation in revision TKA.

Aged↗
PubMed2002

Patella inversion method for exposure in revision total knee arthroplasty.

Satisfactory performance of revision total knee arthroplasty (TKA) requires adequate exposure. This article shows the patella inversion method of exposure in a large consecutive series of revision TKAs.Between 1987 and 1999, 420 revision TKAs were performed. Exposure was facilitated by the patella inversion method. No attempt was made to evert the patella. This technique of exposure was used in 95% (397 of 420) of patients. There were no episodes of patellar tendon avulsion in this series. Multiple exposure options are available in revision TKA. Extensile techniques violate the extensor mechanism. For most patients, these methods were unnecessary. The patella inversion method afforded adequate exposure in most patients without violating the extensor mechanism.

Arthroplasty, Replacement, Knee↗
PubMed2002

Success rate of modular component exchange for the treatment of an unstable total hip arthroplasty.

Hip instability is the leading cause of morbidity after total hip arthroplasty. Surgical strategies that have been used to eliminate recurrent instability include component revision, trochanteric advancement, or the use of constrained components. Between 1986 and 1997, 731 revision total hip arthroplasties were performed at our institution. A total of 29 patients underwent modular component exchange to treat hip instability. After revision surgery, 16 of 29 (55%) patients experienced redislocation. Nine (31% overall) patients dislocated repeatedly after modular component exchange. Five of the 9 patients who dislocated repeatedly (17% overall) ultimately required rerevision to obtain stability. Modular component exchange is an unpredictable procedure in definitively solving hip stability problems. The limitations of this procedure in treating this complex multifactorial problem must be understood by patient and surgeon alike.

Adult↗
PubMed2002

Polyethylene exchange only for prosthetic knee instability.

From 1987 to 1996, 47 revision total knee arthroplasties were done for tibiofemoral instability. Sixteen of these patients had polyethylene exchange only to treat their instability. Fourteen of these patients were available for review. The mean followup was 56 months. The mean Hospital for Special Surgery Knee Score increased from 50 points preoperatively to 73 points at the most recent followup. Clinically, stable knees were produced in 71% of patients (10 of 14). The results of the current study suggest that polyethylene exchange can be an effective, low morbidity procedure to treat certain types of prosthetic knee instability. A failure rate of 29% (four of 14) however, is concerning. Alternative methods of stabilization should be used, if there is any question concerning the stability of a construct where a polyethylene exchange only is used.

Adult↗