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Although current concepts of anterior femoroacetabular impingement predict damage in the labrum and the cartilage, the actual joint damage has not been verified by computer simulation. We retrospectively compared the intraoperative locations of labral and cartilage damage of 40 hips during surgical dislocation for cam or pincer type femoroacetabular impingement (Group I) with the locations of femoroacetabular impingement in 15 additional hips using computer simulation (Group II). We found no difference between the mean locations of the chondrolabral damage of Group I and the computed impingement zone of Group II. The standard deviation was larger for measures of articular damage from Group I in comparison to the computed values of Group II. The most severe hip damage occurred at the zone of highest probability of femoroacetabular impact, typically in the anterosuperior quadrant of the acetabulum for both cam and pincer type femoroacetabular impingements. However, the extent of joint damage along the acetabular rim was larger intraoperatively than that observed on the images of the 3-D joint simulations. We concluded femoroacetabular impingement mechanism contributes to early osteoarthritis including labral lesions. LEVEL OF EVIDENCE: Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

THA revisions using standard cups are at risk of dislocation (5.1% to 14.4% incidence), especially in patients over 70 years of age. Constrained tripolar cups have reduced this risk (6% incidence) but are associated with substantial loosening rates (9%). The nonconstrained dual mobility cup was designed to improve prosthetic stability (polyethylene head ≥ 40 mm diameter) without increasing loosening rates by reducing wear and limiting impingement (rotation range of 108°). We implanted 88 cemented dual mobility cups for THA revisions in 82 patients at high risk of dislocation. Average patient age was 72 years (range, 65–86 years). Eighty-five of the 88 hips were reviewed at 2 to 5 years followup. One patient (1.1%) had a traumatic dislocation at 2 years postoperatively. Two patients (2.3%) had asymptomatic early loosening and three patients (3.5%) had localized radiographic lucencies. These results confirm those with press-fit dual mobility cups suggesting a low dislocation rate at 5 years and a cup survival of 94.6%. At middle term followup, cemented dual mobility cup achieved better results than constrained cups in cases at risk of dislocation and recurrent loosening. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Some previous studies suggest that aging influences wear and oxidatively degraded nonsterilized ultra-high-molecular-weight polyethylene (UHMWPE) exhibits decreased wear resistance. We therefore asked whether shelf-aging storage conditions influenced degradation and wear resistance of gamma-irradiated UHMWPE. We examined oxidation and wear of 100-Mrad gamma-irradiated UHMWPE (100-Mrad polyethylene) cups shelf-aged for 30 years without (n=2) or with (n=2) packages. The oxidation index of the unpackaged 100-Mrad polyethylene surface (4) was higher than that of the packaged one (2.7). The packaged 100-Mrad polyethylene cup exhibited a high wear resistance with a steady wear rate of 0.5 mg/10(6) cycles. In contrast, the unpackaged 100-Mrad polyethylene exhibited an extremely high initial wear rate of 187.9 mg/10(6) cycles over the first 0.25 x 10(6) cycles with a subsequently reduced wear rate of 5 mg/10(6) cycles after 5 x 10(6) cycles. Packaging over long periods inhibits surface oxidation and maintains the wear resistance of gamma-irradiated UHMWPE cups.

Most previous studies of THA in sickle cell disease report high risks of medical and orthopaedic complications, including infections and a higher incidence of failure than observed after THA for osteonecrosis related to other conditions. Based on our experience (1245 orthopaedic procedures during the last 25 years), we questioned these conclusions and retrospectively reviewed 312 arthroplasties performed in 244 patients with sickle cell disease. The mean age of the 126 women and 118 men at the time of surgery was 32 years. The minimum followup was 5 years (mean, 13 years; range, 5–25 years). We revised 10 hips (3%) for infection at a mean 11 years (range, 7–15 years) after the primary procedure and revised 21 cups (8%) and 17 stems (5%) for aseptic loosening at a mean of 14 years. We observed medical complications after 85 operations (27%) and orthopaedic complications in 42 cases (13%). Although THA carries a high risk of complication in patients with sickle cell disease, the benefits for the patient are substantial, and the risk of revision for loosening or infection appeared less than described in previous literature. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

We modified the posterior approach by preserving the external rotator muscles to enhance joint stability after primary THA. We asked whether this modified posterior approach would have a lower dislocation rate than the conventional posterior approach, with and without a repair of external rotator muscles. We retrospectively divided 557 patients (670 hips) who had undergone primary THA into three groups based on how the external rotator muscles had been treated during surgery: (1) not repaired after sectioning, (2) repaired after sectioning, or (3) not sectioned and preserved. The minimum followup was 1 year. In the group with preserved external rotator muscles, we observed no dislocations; in comparison, the dislocation rates for the repaired rotator group and the no-repair group were 3.9% and 5.3%, respectively. This modified posterior approach, which preserves the short external rotator muscles, seemed effective in preventing early dislocation after primary THA.Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

We conducted a randomized clinical trial to compare periacetabular bone density changes after total hip arthroplasty using press-fit components with soft and hard liner materials. Bone density changes were assessed using quantitative computed tomography-assisted osteodensitometry. Twenty press-fit cups with alumina ceramic liners and 20 press-fit cups with highly cross-linked polyethylene liners were included; the nonoperated contralateral side was used as the control. Computed tomography scans were performed postoperatively and 1 year after the index operation. At the 1-year followup, we found no differences of periacetabular bone density changes between the alumina and polyethylene liner cohorts. However, we observed marked periacetabular cancellous bone density loss (up to −34%) in both cohorts. In contrast, we observed only moderate cortical bone density changes. The decrease of periacetabular cancellous bone density with retention of cortical bone density after THA suggests stress transfer to the cortical bone.

Osteonecrosis after bone marrow transplantation is usually severe. Most patients develop acute and chronic graft-versus-host disease requiring a high dose of steroids for a long period of time. Generally ineffective nonoperative treatment in the past has resulted in treatment primarily with total hip arthroplasty (THA). We asked whether THA (1) reliably improved functional status, (2) led to more complications, and (3) THA after bone marrow transplantation was as durable as THA for idiopathic ON. We retrospectively reviewed 77 patients (123 hips) with osteonecrosis. The mean age at surgery was 33 years (range, 15.7–56 years). We performed all arthroplasties with an alumina ceramic bearing coupled with an alumina head 32 mm in diameter. The minimum followup was 2 years (mean, 9.2 years; range, 2–26 years). We documented seven revisions: three for late septic loosening, four for late aseptic loosening. Considering loosening of any component as the end point, the survivorship was 74.8% (range, 58.7%–90.9%) at 10 years. In this difficult situation, we believe the results acceptable. Septic loosening affecting this specific population has to be considered a serious event. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

To augment cement–bone bonding, we interposed hydroxyapatite granules at the cement–bone interface (bioactive bone cement technique). Hydroxyapatite granules (2–3 g) were smeared on the bone surface of the acetabulum and femur just before cementing. We used porous hydroxyapatite granules 300 to 500 μm in diameter from 1986 to 1988 (first generation) and granules 100 to 300 μm in diameter from 1989 to 1991 (second generation). We followed 151 patients (222 hips) in the first generation and 170 patients (252 hips) in the second generation. The minimum followup was 15 years (mean, 17.3 years; range, 15–20 years). Radiolucent lines or spaces less than 1 mm were observed in four hips (1.8%) in the first generation and in 15 hips (6.2%) in the second generation. Osteolysis was observed in one hip (0.5%) in the first generation and six hips (1.6%) in the second generation. We observed loosening in two cups (0.8%) in the second generation. The long-term clinical results suggest the interface bioactive bone cement technique combined with our other techniques results in low incidences of radiolucent lines (spaces) and osteolysis, and may increase the longevity of cemented THA. The data suggest the larger hydroxyapatite granules performed better than smaller ones. Level of Evidence: Level III, therapeutic retrospective cohort series. See the Guidelines for Authors for a complete description of levels of evidence.

Femoral stems with reduced stiffness have the potential of decreasing stress shielding and could be an alternative in revision surgery when restoration of bone stock is required. We retrospectively reviewed 38 patients (40 stems) with a central core of cobalt-chromium surrounded by a polymer and an outer titanium mesh layer containing a proximal coating of hydroxyapatite/tricalcium phosphate; 30 of the 38 patients (32 hips) had a minimum 2-year followup. We impacted morselized allograft around the stem in 28 of 32 revisions. Repeated radiostereometric examinations showed medial, distal, and posterior migration (median, 0.21 mm, 0.17 mm, and 0.96 mm, respectively) of the femoral head center for up to 6 months followed by stabilization. Measurements of bone mineral density in the seven Gruen zones at 6 months revealed either a decrease (down to a median of 3%), no change, or a slight increase (up to 5%) followed by a further increase up to 2 years in three of the regions (2, 3, and 5). Conventional radiography at 2 years demonstrated graft remodeling and incomplete radiolucent lines in 19 hips, mainly in Regions 1 and 7. Two hips were reoperated on as a result of dislocation, but none of the stems had been revised.Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

The Exeter Universal hip (Stryker Inc., Newbury, UK) has reported survival rates of 91.74% at 12 years in all patients with reoperation as an endpoint. However, its performance in younger patients has not been fully established. We reviewed survivorship and the clinical and radiographic outcomes of this hip system implanted in 107 patients (130 hips) 50 years old or younger at the time of surgery. The mean age at surgery was 42 years. The minimum followup was 10 years (mean, 12.5 years; range, 10-17 years) with no patients lost to followup. Twelve hips had been revised. Of these, nine had aseptic loosening of the acetabular component and one cup was revised for focal lysis and pain. One hip was revised for recurrent dislocation and one joint underwent revision for infection. Radiographs demonstrated 14 (12.8%) of the remaining acetabular prostheses were loose but no femoral components were loose. Survivorship of both stem and cup from all causes was 92.6% at an average of 12.5 years. Survivorship of the stem from all causes was 99% and no stem was revised for aseptic loosening. The Exeter Universal stem performed well, even in the young, high-demand patient.Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Different bearing surfaces, including alumina-on-alumina, have been used to avoid osteolysis. We prospectively followed 288 patients (319 hips) in which an alumina-on-alumina cup was used with a hydroxyapatite stem. The patients' mean age was 52.7 (range, 14-70 years), and the minimum followup was 3 years (mean, 4.7 years; range, 3-8 years). At final followup, five cups (including one with an alumina liner fracture) and two stems underwent revision. The cumulative probability of not having a revision of one or both components for any cause was 97% (95% confidence interval, 94.7%-99.1%). No patient spontaneously reported any noises from the hip and none reported noises when specifically questioned. All patients who had not undergone revision had good clinical results, but five of these patients had radiographic cup loosening at last followup. These data suggest alumina-on-alumina prostheses had reasonable outcomes after 5 years. One acetabular component fractured from trauma. We observed no linear femoral head penetration. Continued followup will be required to determine if reduction in wear between the alumina-on-alumina bearings results in less osteolysis and loosening.Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

The etiology of osteoarthritis of the hip has long been considered secondary (eg, to congenital or developmental deformities) or primary (presuming some underlying abnormality of articular cartilage). Recent information supports a hypothesis that so-called primary osteoarthritis is also secondary to subtle developmental abnormalities and the mechanism in these cases is femoroacetabular impingement rather than excessive contact stress. The most frequent location for femoroacetabular impingement is the anterosuperior rim area and the most critical motion is internal rotation of the hip in 90° flexion. Two types of femoroacetabular impingement have been identified. Cam-type femoroacetabular impingement, more prevalent in young male patients, is caused by an offset pathomorphology between head and neck and produces an outside-in delamination of the acetabulum. Pincer-type femoroacetabular impingement, more prevalent in middle-aged women, is produced by a more linear impact between a local (retroversion of the acetabulum) or general overcoverage (coxa profunda/protrusio) of the acetabulum. The damage pattern is more restricted to the rim and the process of joint degeneration is slower. Most hips, however, show a mixed femoroacetabular impingement pattern with cam predominance. Surgical attempts to restore normal anatomy to avoid femoroacetabular impingement should be performed in the early stage before major cartilage damage is present. Level of Evidence: Level V, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence

Contains fulltext : 70283.pdf (Publisher’s version ) (Closed access) Acetabular bone loss hampers implantation of a total hip arthroplasty in patients with developmental dysplasia of the hip. The bone impaction grafting technique in combination with a cemented total hip can restore the bone stock in these patients, but do these reconstructions yield satisfying long-term results? We used this technique in 28 hips (22 consecutive patients). The degree of dislocation was graded preoperatively as Crowe I in five hips, Crowe II in eight hips, Crowe III in nine hips, and Crowe IV in four hips. We present the long-term results of this bone impaction grafting technique a minimum of 10 years after surgery. Two patients died before the minimum followup of 10 years, leaving 20 patients (26 hips). Two cups were revised, one cup for a sciatic nerve palsy (at 2 years) and the other for aseptic loosening after 12 years. The cumulative survival of the cup with revision for any reason as the end point was 96% at 10 years and 84% at 15 years. There were no femoral revisions during followup. The bone impaction grafting technique in combination with a cemented cup is an effective technique for developmental dysplasia of the hip with favorable long-term results. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.