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Biomedical subjects

Cecil H Rorabeck

Publications and source records attributed to Cecil H Rorabeck.

At least 37 records · Page 2Linked to original sources
PubMed2004

Retroacetabular osteolysis: when to operate?

Polyethylene liner exchange for retroacetabular osteolysis should be done before the shell becomes loose. The purpose of this study was to determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell. Between 1992 and 2002, 46 cementless shells were revised at our institution for aseptic osteolysis. Radiographs and a computer-assisted technique were used to quantify osteolysis. Implant stability was confirmed intraoperatively. Of 26 stable and 20 loose shells, the average area of osteolysis on anteroposterior radiographs showed no significant difference, whereas lateral radiographs showed a difference. The percentage of shell circumference with associated osteolysis seen on anteroposterior and lateral radiographs showed a significant difference. Diagnostic criterion of 50% shell circumference associated with osteolysis on lateral films has a sensitivity of 0.84 and a specificity of 0.54, and on anteroposterior views, a sensitivity of 1.0 and a specificity 0.27 for predicting shell loosening. Percent of shell circumference with surrounding osteolysis seems to be more predictive of loosening than the area of osteolysis. When 50% of the shell circumference has osteolysis evident on anteroposterior or lateral radiographs, but preferably anteroposterior radiographs, liner exchange should be considered so that the exchange procedure is still possible, rather than allowing the osteolysis to increase and compromise shell fixation.

Acetabulum↗
PubMed2003

Effect of cementless bowed stem distal surface contour and coronal slot on femoral bone strains and torsional stability.

Six pairs of unembalmed cadaver femurs were instrumented with strain gauges and prepared with flexible reamers for insertion of long bowed cementless femoral stems. A fully porous-coated cobalt chrome stem was inserted into each left femur, and a distally fluted, slotted, stem of the same implant geometry and implant material was inserted into each right femur. Bone strains were measured during stem insertion and torsional stability tested after the stems were fully seated. Distal strains were significantly higher (p < 0.05) for the fully porous compared to the distally fluted, slotted stem. Three fractures occurred in femurs with fully porous-coated stems. There was no difference in torsional stability between the two stem geometries. Our data demonstrate that a long bowed cementless stem with a distal coronal slot and flutes is associated with decreased bone strains and fracture risk during stem insertion compared to a fully porous-coated stem.

Biomechanical Phenomena↗
PubMed2003

Resurfacing versus not resurfacing the patella in total knee arthroplasty: 8- to 10-year results.

Patellar resurfacing in total knee arthroplasty is a topic debated in the literature. Concerns include fracture, dislocation, loosening, and extensor mechanism injury. Residual anterior knee pain has been reported when the patella is not resurfaced. One hundred patients with osteoarthritic knees were prospectively randomized to either have their patella resurfaced or left not resurfaced. All patients were treated with a single prosthesis that featured an anatomically designed patellofemoral articulation (Anatomic Medullary Knee, DePuy, Warsaw, IN) Two patients in the unresurfaced group and one in the resurfaced group required repeat surgery for patellofemoral complications. At 8- to 10-year follow-up evaluations, Knee Society Clinical Ratings scores were not different between the 2 groups. Rates of anterior knee pain with walking and stair climbing were significantly less in the resurfaced group. Eighty percent of patients with a resurfaced patella were extremely satisfied with their total knee arthroplasty versus 48% without patellar resurfacing. When satisfied and extremely satisfied patients were grouped together, there was no difference between the 2 groups.

Aged↗
PubMed2003

Surface analysis of posterior stabilized femoral components used in total knee arthroplasty.

The purpose of this study was to evaluate the preimplantation surface finish of the femoral component used in total knee arthroplasty. Nine femoral components from various manufacturers were obtained for analysis. All were fixed-bearing, posterior-stabilized implants intended for cemented arthroplasty. Surface characterization involved light profilometry over multiple surface points from the condylar surface, trochlear groove, and the posterior stabilizing cam. Results revealed that the condylar surface roughness was not significantly different when comparing designs with a mean roughness average ranging from 43.6 to 116 nm. The trochlear surface was generally similar to that of the condyles in most implants, although significant differences were seen in 2 implants (P <.05). Of note, the articular surface of the stabilizing cam was uniformly rougher than the condylar surface in all implants and significantly rougher (P <.05) in 6 of the 9 components.

Arthroplasty, Replacement, Knee↗
PubMed2003

Subtrochanteric shortening and derotational osteotomy in primary total hip arthroplasty for patients with severe hip dysplasia: 5-year follow-up.

Twenty-one primary hip arthroplasties were performed in Crowe grade 3 or 4 hip dysplasia using a subtrochanteric shortening osteotomy. Average patient age was 48.2 years. Average follow-up was 5.8 years (minimum, 2 years). Femoral fixation was cemented in 10 hips and uncemented in 11 hips. All acetabular components were uncemented, with 33% requiring structural autograft. Ninety-one percent of femoral osteotomies healed without complication. Two osteotomy nonunions required revision. Two acetabular revisions were performed for malposition and polyethylene failure. Three patients experienced postoperative dislocation. One cemented femoral component was revised for loosening. However, no neurologic deficiencies were identified. Harris hip score improved from 32.5 to 73.6. Limp improved in 60% of patients and dependence on assistive walking device improved in 40% of patients. Subtrochanteric shortening osteotomy is a safe and predictable method of restoring the anatomic hip center in high developmental hip dislocation. However, the complication rate in these patients is higher than primary hip arthroplasty for osteoarthritis.

Adult↗
PubMed2003

Patellar options in revision total knee arthroplasty.

There are numerous options that need to be considered by the surgeon at the time of revision total knee arthroplasty (TKA). One needs to consider the reason for the revision, the type of patella in place, and the length of time the patella has been in place. The surgeon also needs to consider the status of the patellar bone stock, the stability of the patellar component (well-fixed or loose), and the component type (cemented or metal-backed). Assuming that the existing prosthesis is not metal-backed and has minimal PE wear, then it is preferable to retain a well-fixed all-PE cemented patellar button. However, if the button is metal-backed, then it probably is best to remove the button and replace it with an all-PE domed patellar component. Assuming more than 8 mm of patellar bone stock is remaining, it usually is best to cement an all-PE dome-shaped patella. However, if less than 8 mm is remaining, then that patient can be left with a patelloplasty, recognizing that this individual is going to continue with a high likelihood of anterior knee pain, subluxation, and poor functional results. In that situation, it may be preferable to consider a bone stock augmentation.

Arthroplasty, Replacement, Knee↗
PubMed2003

Extended trochanteric osteotomy via the direct lateral approach in revision hip arthroplasty.

A review of the results of the extended trochanteric osteotomy through a modified direct lateral approach in revision total hip arthroplasty was done. We reviewed 44 patients (45 procedures) at a minimum of 2 years followup (mean, 3.8 years; range, 2.1-7.2 years). There were 26 men and 18 women with a mean age at the time of surgery of 70.8 years (range, 36.9-90.4 years). Indications for use of the trochanteric osteotomy included facilitation of cement removal (25 procedures), proximal femoral varus deformity (14 procedures), trochanteric malposition (five procedures), and previous trochanteric osteotomies with significant bony overgrowth (three procedures). The mean length of the osteotomy was 133.9 mm. The mean migration of the osteotomized fragment was 2.1 mm (range, 0-20 mm) with significantly more proximal migration seen with the use of cerclage wires when compared with cables. There were two cases of trochanteric escape, for which the patients required repeat open reduction internal fixation. There were two late fractures of the greater trochanter. One femoral component had early subsidence for which the patient required re-revision with a further extended trochanteric osteotomy. The mean time to union of the remaining 40 hips was 10.3 months (range, 6-24 months). There only was one dislocation postoperatively. The extended trochanteric osteotomy through the modified direct lateral approach in revision total hip arthroplasty is a reproducible and reliable technique with a lower dislocation rate but a higher incidence of trochanteric fracture and escape than previously described with its use in the posterior approach.

Adult↗
PubMed2003

Validation of two and three-dimensional radiographic techniques for measuring polyethylene wear after total hip arthroplasty.

BACKGROUND: Three-dimensional radiographic techniques have been developed to estimate in vivo polyethylene wear of total hip replacements. We are not aware of any published study examining the accuracy of these in vivo methods. Our objective was to validate two radiographic techniques by comparing their results with those obtained directly from retrieved specimens. METHODS: A coordinate measuring machine was used to probe the interior bearing surface of seventeen acetabular liners that had been retrieved at revision surgery. Solid models were created to determine volumetric polyethylene loss and linear depth and direction of wear. Two in vivo radiographic techniques (PolyWare and the Martell Hip Analysis Suite) were used to calculate two-dimensional linear, three-dimensional linear, and volumetric wear. The radiographic analysis was done independently, and the results were compared with the known values of polyethylene wear derived with use of the coordinate measuring machine. RESULTS: Correlation coefficients comparing the values for two-dimensional and three-dimensional linear wear and volumetric wear derived with the PolyWare radiographic technique with the values derived with the coordinate measuring machine were r(2) = 0.78, r(2) = 0.75, and r(2) = 0.91, respectively (all p < 0.001), and the correlation coefficients comparing the values derived with the Martell Hip Analysis Suite radiographic technique with those derived with the coordinate measuring machine were r(2) = 0.80, r(2) = 0.84, and r(2) = 0.91, respectively (p < 0.001). The average absolute difference between the radiographic estimates and the results derived with the coordinate measuring machine was approximately 19% (range, 13% to 24%). CONCLUSIONS: There was good agreement between the wear estimates made with both in vivo techniques and the measurements of the retrieved polyethylene liners made with the coordinate measuring machine. Two-dimensional wear analysis (based on anteroposterior radiographs) accounted for most of the polyethylene wear, while one technique of three-dimensional wear analysis (PolyWare) demonstrated some additional wear in the lateral plane.

Arthroplasty, Replacement, Hip↗
PubMed2003

Porous coated femoral fixation: the long and short of it!

Tapered cementless stems have several advantages and represent what we believe is the gold standard of cementless femoral stems (Figure 3). Durability is excellent and as good as any cemented stem. The tapered shape and the use of titanium alloy reduce the stiffness of these tapered cementless stems, leading to less thigh pain and stress shielding. In addition, the use of cementless tapered stems simplifies the surgical procedure to ream, broach, trial, and insert.

Aged↗
PubMed2002

Health-related quality of life and mobility of patients awaiting elective total hip arthroplasty: a prospective study.

BACKGROUND: Waits for elective total hip arthroplasty for osteoarthritis are common in publicly funded health care systems, but they may lead to poorer postoperative outcomes and loss of health-related quality of life (HRQOL) through progressive pain and immobility during the wait. These issues have not been examined from the time of referral for surgery. Our primary objective was to test whether a longer wait was associated with poorer postoperative HRQOL. METHODS: Patients needing possible total hip arthroplasty for osteoarthritis were identified upon referral to a surgeon in London, Ont. Outcome measures, including the Western Ontario McMaster (WOMAC) Osteoarthritis Index and mobility in the 6-Minute Walk, were assessed at baseline and every 3-6 months thereafter until at least 3 months after the surgery. RESULTS: Of 553 potentially eligible patients referred for surgical assessment, 123 were placed on a waiting list for total hip arthroplasty; 114 underwent the procedure, and 99 of them returned for postoperative assessment. No significant differences in HRQOL or mobility were seen postoperatively between patients with short waits and those with long waits (a priori definitions < or = 6 months and > 6 months respectively). At referral, however, patients with short waits had poorer HRQOL and were less mobile than those with long waits (p = 0.002 for WOMAC Osteoarthritis Index total score, 0.001 for pain, 0.009 for stiffness and 0.008 for function; p = 0.006 for 6-Minute Walk results). Patients with short waits experienced larger gains in these measures from the time of referral until the postoperative assessment than did patients with long waits (p = 0.002 for WOMAC Osteoarthritis Index total score, < 0.001 for pain, 0.005 for stiffness and 0.005 for function; p = 0.06 for 6-Minute Walk results). For patients with long waits, increases in the WOMAC Osteoarthritis Index total score exceeded 10% and losses in walking distance exceeded 30 m from the time of referral to surgery. INTERPRETATION: The length of wait for elective total hip arthroplasty is not associated with postoperative HRQOL and mobility. However, patients who undergo the procedure within 6 months after referral have greater disability at referral, and realize greater gains in HRQOL and mobility after surgery, than patients waiting more than 6 months. Clinically important losses in HRQOL and mobility occur in patients waiting more than 6 months.

Aged↗
PubMed2002

Press-fit versus cemented all-polyethylene patellar component: midterm results.

This study compared the midterm results between press-fit and cemented implantation of a highly congruent, all-polyethylene patellar component. We followed prospectively 172 implants (cemented, n = 133; press-fit, n = 39). Average follow up was 6 years (range, 5-8 years). Patellofemoral complications occurred in 4 cemented patellae (2.3%). Two of these patellae required revision. Cemented implants had a significantly higher incidence of patellar maltracking (30% vs 8%; P= .005). No significant differences in the overall Knee Society scores (mean, 165; SD, 27) or any of its components relevant to patellofemoral function were detected between fixation methods. A retrieved specimen showed an intervening fibrous membrane at the implant-bone interface. The potential for macrophage-mediated osteolysis at this site is unknown. No other adverse outcome was associated with press-fit implantation. These results suggest that at midterm follow-up, press-fit implantation of this all-polyethylene patellar component may improve tracking and represents a viable alternative to cement fixation.

Aged↗
PubMed2002

Soft tissue balancing: the hip.

During total hip arthroplasty, femoral offset is restored in only 40% of patients. Increased attention to techniques that ensure leg-length and offset restoration improve total hip arthroplasty function and minimize the risk of complications such as dislocation and limp. Preoperative templating, intraoperative leg-length offset measurements, and the availability of high-offset femoral necks can improve the restoration of offset in 90% of patients.

Arthroplasty, Replacement, Hip↗
PubMed2002

Heterotopic ossification after revision total knee arthroplasty.

A consecutive series of revision total knee arthroplasties done at two centers was evaluated for the presence of heterotopic ossification on radiographs taken before and after revision using the classification system of Harwin et al. Knee Society scores were obtained preoperatively and at annual intervals postoperatively. The patients' demographics and clinical scores were correlated with the incidence and grade of heterotopic ossification. Minimum 2-year followup was obtained in 135 of 151 patients who had revision total knee arthroplasty during this period (89%). The incidence of heterotopic ossification before revision surgery was 23%, which increased to 56% at most recent followup (mean, 30 months; range, 24-48 months). The only risk factor identified for the development of heterotopic ossification was the presence of infection (76%), which was significantly higher than the 47% incidence of heterotopic ossification in patients who did not have an infection. The average postoperative Knee Society score was lower in patients with heterotopic ossification compared with patients without heterotopic ossification (129 points versus 148 points). Patients with heterotopic ossification had significantly lower functional scores particularly on stair climbing but did not have a significantly decreased range of motion. Parameters not associated with subsequent development of heterotopic ossification included gender (males), patient size (body mass index), surgical time, operative approach, or number of prior knee procedures.

Arthroplasty, Replacement, Knee↗