The patient-specific Triflange acetabular implant for revision total hip arthroplasty in patients with severe acetabular defects: planning, implantation, and results.

AIMS: Few reconstructive techniques are available for patients requiring complex acetabular revisions such as those involving Paprosky type 2C, 3A and 3B deficiencies and pelvic discontinuity. Our aim was to describe the development of the patient specific Triflange acetabular component for use in these patients, the surgical technique and mid-term results. We include a description of the pre-operative CT scanning, the construction of a model, operative planning, and surgical technique. All implants were coated with porous plasma spray and hydroxyapatite if desired. PATIENTS AND METHODS: A multicentre, retrospective review of 95 complex acetabular reconstructions in 94 patients was performed. A total of 61 (64.2%) were female. The mean age of the patients was 66 (38 to 85). The mean body mass index was 29 kg/m2 (18 to 51). Outcome was reported using the Harris Hip Score (HHS), complications, failures and survival. RESULTS: The mean follow-up was 3.5 years (1 to 11). The mean HHS improved from 46 (15 to 90) pre-operatively to 75 (14 to 100). A total of 21 hips (22%) had at least one complication with some having more than one; including dislocation (6%), infection (6%), and femoral complications (2%). The implant was subsequently removed in five hips (5%), only one for suspected aseptic loosening. CONCLUSION: The Triflange patient specific acetabular component provides predictable fixation with complication rates which are similar to those of other techniques. Cite this article: Bone Joint J 2018;100-B(1 Supple A):50-4.

Survivorship analysis of acetabular revision in medial, lateral, and global primary osteoarthritis.

Acetabular revision rates after cemented total hip arthroplasty vary from series to series in the literature. Little attention has been paid to the type of primary osteoarthritis in these previous series. We studied 782 cemented total hips in 671 patients with an average follow up of 7.5 years. Acetabular revision rates were analyzed in medial, lateral, and global primary osteoarthritis using survivorship analysis. Medial osteoarthritis was associated with a higher acetabular revision rate when compared to lateral osteoarthritis (P = .015). No differences were noted in acetabular revision rates when the preoperative diagnosis was medial vs global or lateral vs global primary osteoarthritis (P = .18 and P = .45, respectively). According to this study, a preoperative diagnosis of medial primary osteoarthritis should be added to a list of several factors associated with increased cemented acetabular failure, especially in the Charnley prosthesis.

Polyethylene wear in total hip arthroplasty.

Polyethylene wear increasingly has been blamed for osteolysis and granuloma formation after total joint arthroplasty. The authors evaluated the wear difference between bearing surfaces of stainless steel, cobalt chrome, and titanium alloy. They also compared cemented all-polyethylene molded cups with cemented metal-backed molded acetabular cups. These were compared with molded and machined polyethylene cups. Two patient groups were matched individually for gender, age, weight, and length of followup. Analyses were done using the technique of Livermore et al. The bearing surface evaluation consisted of 3 groups after matching, leaving 77 patients per group. Results showed linear wear rates of 0.06 mm per year, 0.05 mm per year, and 0.08 mm per year for stainless steel, cobalt chrome, and titanium alloy, respectively. The comparison between cemented molded metal-backed and nonmetal-backed acetabular components was not matched, with 134 metal-backed and 99 nonmetal-backed components. Results showed linear wear rates of 0.011 mm per year in the metal-backed group and 0.08 mm per year in the nonmetal-backed group. Results were statistically significant. These results indicate that the metal composition of the femoral bearing surface has minimal, if any, effect on the linear polyethylene wear rate. The method of polyethylene fabrication and the use of metal backing had a significant effect on the polyethylene wear rate in these patient groups. These results suggest that the compression-molded all-polyethylene acetabular component may be optimal for reducing polyethylene wear in total hip arthroplasty.

A new radiographic evaluation of primary osteoarthritis.

Two thousand five hip radiographs, both AP and lateral, were evaluated for osteoarthritis. We excluded all cases of traumatic osteoarthritis, rheumatoid arthritis, avascular necrosis, and congenital deformities. This left 1578 hips in 1309 patients, which were sub-divided into three categories: medial osteoarthritis (405 hips, 20% of which were bilateral, 68% women, 32% men); superior lateral osteoarthritis (934 hips, 19% of which were bilateral, 49% men, 51% women); and global osteoarthritis (239 hips, 23% bilateral, 53% men, 47% women). These categories may have significance in operative technique and survival of acetabular cups after total hip arthroplasty.

Polyethylene wear in cemented metal-backed acetabular cups.

We examined radiographic polyethylene wear in 233 cemented total hip arthroplasties (201 patients) with either a metal-backed or a non-metal-backed acetabular cup. All patients had identical cemented one-piece titanium femoral stems with a femoral head diameter of 28 mm. The mean linear wear rate was 0.11 mm/yr in metal-backed sockets and 0.08 mm/yr in non-metal-backed sockets (p = 0.0002). The mean volumetric wear rate was 66.2 mm3/yr in the metal-backed sockets and 48.2 mm3/yr in the polyethylene sockets (p = 0.0002). The addition of metal backing to a cemented acetabular cup therefore resulted in a 37% increase in mean polyethylene wear rates which may partially explain the higher failure rate of cemented metal-backed cups. Linear regression analysis also implicated increased follow-up time (log), gross acetabular migration, metal backing and male gender in increasing polyethylene wear. We advocate the use of an all-polyethylene cup in cemented total hip arthroplasty. The increased polyethylene wear must also cause concern about the wear rate of uncemented metal-backed acetabular sockets.

Deformities of the forearm in patients who have multiple cartilaginous exostosis.

Thirty-five patients who had multiple cartilaginous exostosis and deformities of the wrist and forearm were evaluated to determine the natural history and prognostic factors for the deformities. Radial and ulnar shortening were correlated linearly (r2 = 0.86), showing that both bones of the forearm were symmetrically involved. The angular growth abnormality of the distal aspect of the radius was correlated with radial shortening (r2 = 0.53) and ulnar shortening (r2 = 0.61), but it had no correlation with negative variance of the ulnar (r2 = 0.30). Carpal slip was an independent factor, with no correlation with any of the factors studied. The ulnar tether theory for deformities of the wrist in patients who have multiple cartilaginous exostosis was not substantiated by this study.

Intramedullary versus extramedullary femoral alignment systems in total knee replacement.

The accuracy of intramedullary (IM) versus extramedullary (EM) distal femoral alignment systems was compared in 200 consecutive total knee replacements (TKRs) on standing full-length lower-extremity roentgenographs. Intramedullary femoral alignment systems were used in 125 TKRs and an EM system was used in 75 TKRs. All tibial cuts were made using an EM tibial cutting guide. Roentgenographic measurements of (1) femoral-tibial angle, (2) distal-femoral resection angle, (3) proximal-tibial resection angle, (4) joint line orientation, (5) physiologic femoral valgus, and (6) distance of the lower-extremity mechanical axis from the center of the knee were made. No significant intragroup differences were seen in the average values obtained for each of the six roentgenographic measurements. However, the percentage of distal-femoral resections outside the accepted normal range (94 degrees-100 degrees) was higher in the EM group (28%) versus the IM group (14.4%) at p = 0.019. Likewise, the percentage of joint line orientations outside the desired normal range was higher in the EM groups when compared with the IM group (21.3% versus 11.2%, p = 0.052). A disturbing number of proximal-tibial resection angles were inaccurate in both groups. Improper tibial cuts were seen in 20.6% of Group 1 and in 24% of Group 2 when an EM tibial cutting guide was used. A range of distal-femoral cuts exists when using either an IM or an EM femoral alignment guide. This study demonstrated a statistically significant improvement in distal-femoral resection accuracy when using an IM femoral alignment system. Methods of improving proximal-tibial bone resections are needed.(ABSTRACT TRUNCATED AT 250 WORDS)

Early clinical results of hydroxyapatite-coated total hip arthroplasty.

A retrospective clinical and radiographic review of 25 conventional cementless total hip replacements (THRs) and 25 cementless hydroxyapatite-coated THRs was performed to evaluate early postoperative results. The hydroxyapatite-coated group had a higher incidence of pain-free arthroplasties compared with the standard cementless group (72% v 44%, P = .045) at the 2-month postoperative evaluation. At the 6-month evaluation, 76% of hydroxyapatite-coated THRs were pain-free compared with 52% of conventional cementless THRs, although the statistical significance disappears (P greater than .05). No differences between groups existed in the 6-month Harris hip scores, average motion, use of external support, Trendelenberg gait, postoperative implant radiolucent lines. Adding a 50- to 75-mug hydroxyapatite coating to a proximal one-third porous femoral prosthesis and porous surface acetabular cup improved the early clinical results in cementless THR. Whether this improvement in pain scores reflects a more stable cementless prosthesis via increased rates and amount of osseus ingrowth or adjunctive bone hydroxyapatite chemical bonding remains unanswered. Long-term follow-up of femoral subsidence and THR revision is needed to indicate the durability and success of hydroxyapatite coating.

Incidence of brachydactyly and hand exostosis in hereditary multiple exostosis.

Forty-two radiographs and charts of twenty-two patients with a diagnosis of hereditary multiple exostosis and hand involvement were examined to determine the incidence of hand exostoses and association with brachydactyly. An average of 11.6 exostoses were found per hand. The proximal phalanges and metacarpals are affected in the majority of patients and the thumb and distal phalanges are rarely involved. Most exostoses were located in the juxtaepiphyseal region (61.8%) and typically involved less than 50% of the bone diameter. Brachydactyly can be seen in patients with hereditary multiple exostosis when no exostoses is present; however, the presence of an exostosis results in even more shortening. The location and size of the exostosis had no relationship to increased bone shortening. Operative treatment was required in four of twenty-two patients for debulking and impingement.

Endoscopic management of the obliterated ureteroileal anastomosis.

Endoscopic restoration of a totally obstructed ureteroileal anastomosis was accomplished in 3 patients. The combined use of rigid endoscopy of the ileal conduit and flexible nephroureteroscopy provided full visualization of the blind-ending segments and allowed location of the shortest segment between the lumina. A guide wire was passed through intervening tissue with fluoroscopic monitoring to re-establish internal drainage. This technique offers an alternative to laparotomy and reimplantation in selected cases of ureteroileal stricture.