[Successful medial unicompartmental knee arthroplasty-What are the most important surgical tricks?] / Erfolgsfaktoren für den medialen Teilgelenkersatz ­ Was sind die wichtigsten chirurgischen Tricks?

BACKGROUND: Unicompartmental knee arthroplasty (UKA) is an established surgical treatment option for end-stage anteromedial osteoarthritis with excellent functional outcomes and implant survival. Routine preoperative varus and valgus stress views are crucial for the selection of patients for unicompartmental or total knee arthroplasty. THERAPY: UKA is a soft-tissue based operation that aims to reconstruct the individual joint line and pre-arthritic alignment by restoring the physiological tension of the medial collateral and the cruciate ligaments. RESULTS: Current data for medial UKA show excellent results for both mobile and fixed bearing implant designs with the correct indication and surgical technique. Cementless fixation offers potential advantages over cemented implants. Registry data demonstrate that institutions and surgeons specializing in partial knee replacement (> 30 cases/year per surgeon, > 100/year per institution) with a high percentage of UKA relative to the total number of knee implants (> 20%) have significantly lower revision rates.

[New technologies (robotics, "custom-made") for unicondylar knee arthroplasty-contra]. / Neue Technologien (Robotik, "custom made") in der unikondylären Knieendoprothetik ­ Contra.

BACKGROUND: Numerous long-term results for both medial and lateral unicondylar knee arthroplasty (UKA) demonstrate that UKA is a reliable and successful treatment for isolated anteromedial or lateral osteoarthritis of the knee when the correct indications are used. The relationship between operation volume and implant performance has clearly been established from recent studies and registry data. The use of novel technologies allows for an improvement in the accuracy of implant positioning with fewer outliers. However, evidence-based target zones for the positioning of available implants have not been sufficiently established. INDIVIDUAL ENDOPROSTHETICS: Current data does not support the routine use of patient-specific instruments or custom-made implants. ROBOTICS: Robot-assisted procedures must be interpreted as a very promising approach for the future. So far, there is insufficient evidence that robotically assisted surgical techniques improve implant performance or lead to better functional results from the patient's point of view.

High Variability of Acetabular Offset in Primary Hip Osteoarthritis Influences Acetabular Reaming-A Computed Tomography-Based Anatomic Study.

BACKGROUND: The objectives of the present study were to (1) evaluate the accuracy and reliability of native acetabular offset (AO) measurements performed on conventional supine anterior-posterior (ap) pelvis radiographs with reference to computed tomography (CT) in patients with end-stage hip osteoarthritis (OA); (2) determine the minimum and maximum amount of medialization of the center of rotation (COR) simulating different reaming techniques; and (3) identify patients at increased risk of excessive medialization of the COR. METHODS: A consecutive series of corresponding 131 CT scans and radiographs of patients with primary hip OA was evaluated using validated software for three-dimensional acetabular and femoral measurements. We simulated the implantation of a hemispherical press-fit cup comparing anatomic and conventional reaming techniques and assessed corresponding changes in AO. RESULTS: Standardized ap pelvis radiographs allowed for an accurate and reliable assessment of AO compared with CT. Cup placement in the most lateral position (anatomic reaming technique) resulted in a mean implant-related medialization of 5.9 ± 3.4 mm. Anatomic cup placement did not require reaming to the true floor in 64 hips (49%). With the conventional reaming technique, the total medialization of the COR (implant-related and reaming-related) was 6.8 ± 2.9, with 34% of cases having a medialization ≥8 mm. CONCLUSION: The present study highlights the variability of acetabular anatomy in patients with primary OA. AO can be accurately and reliably determined on conventional radiographs and appears to be independent of femoral shape and geometry. Depending on the preferred reaming technique a substantial number of patients appear at risk for excessive cup medialization.

Size of ischial fibro-ostosis is associated with heterotopic ossification after total hip arthroplasty.

PURPOSE: The hypothesis of the present study was that degenerative fibro-ostosis (FO) of the ischial hamstring tendon insertion is a risk factor for heterotopic ossification (HO) following THA. METHODS: We followed 103 consecutive patients (43 males, 60 females, mean age 61 years) who underwent unilateral cementless THA for primary hip osteoarthritis and investigated the incidence of HO within the first 12 months after surgery. On pre-operative radiographs, a standardized evaluation for FO of the ischial hamstring tendon insertion concerning horizontal, vertical, and square dimensions was performed. HO was classified according to Brooker on radiographs at 12 months post-operatively. RESULTS: At follow-up, 56 patients (54%) had no radiographic evidence of HO, 23 (22%) were classified as Brooker I, 17 (17%) as II, 6 (6%) as III, and 1 (1%) as IV, respectively. Patients with post-operative HO had significantly greater vertical (3.0 mm vs. 2.3 mm, p = 0.001) and horizontal (47.9 mm vs. 39.1 mm, p = 0.025) dimensions of FO than patients without HO. Patients with FO and a vertical dimension of ≥ 2.5 mm were more likely to develop HO (55.6%) than patients with a vertical FO dimension of less than 2.5 mm (34.7%, OR = 2.35 p = 0.047). A weak correlation between the vertical and horizontal size of FO and the severity of HO was observed. CONCLUSION: Radiographic evidence of asymptomatic FO is a potential risk factor for the development of HO following THA and may be used as a simple diagnostic tool to pre-operatively identify patients at risk for post-operative HO. This association has not been previously described and further research to confirm the present findings and to justify additional prophylactic treatment in these patients is warranted.

Comparative Analysis of the Reconstruction of Individual Hip Anatomy Using 3 Different Cementless Stem Designs in Patients With Primary Hip Osteoarthritis.

BACKGROUND: We questioned whether there was a radiographic difference in hip geometry reconstruction and implant fixation between 3 different cementless stem design concepts in patients with primary end-stage hip osteoarthritis. METHODS: We retrospectively evaluated the preoperative and postoperative radiographs by 2 independent and blinded reviewers in a series of 264 consecutive patients who had received either a straight double-tapered stem with 3 offset options (group A), a straight double-tapered stem with 2 shape options and modular necks (group B), and a bone-preserving curved tapered stem with 4 offset options (group C). The following parameters were assessed: acetabular, femoral and hip offset (HO), center of rotation height, leg length difference (LLD), and the endosteal fit of stem in the proximal femur (canal fill index). Group comparisons were performed using a one-way analysis of variance and subsequent pairwise comparisons (t-test). RESULTS: Postoperatively, HO could be equally restored with all 3 stem designs (P = .079). The postoperative LLD was smaller in group C compared to group A (0.8 mm [standard deviation, 3.2] vs 2.6 mm [standard deviation, 4.5], P = .002). Best combined reconstruction of HO and LLD could be achieved with the short curved stem by junior and senior surgeons (HO: -2.0 and -2.1 mm; LLD: 1.9 and 0.7 mm, respectively). The proximal and mid-height canal fill indexes were higher in groups B and C compared to group A, indicating a better metaphyseal and diaphyseal fit in the proximal femur (both P < .001). CONCLUSION: All 3 cementless stem designs allowed for good hip geometry reconstruction. Multiple shape and offset options allowed for a better metaphyseal stem fit and offered minor clinical advantages for leg length reconstruction. Modular necks did not provide reconstructive advantages in patients with primary hip osteoarthritis.

Minimally invasive Oxford medial unicompartmental knee arthroplasty in young patients.

PURPOSE: Advanced knee arthritis in young patients is a challenging problem that may necessitate surgical treatment. There are few published studies of mobile-bearing unicompartmental knee arthroplasty (UKA) in young patients, while indications have expanded to its use in this demanding patient group. METHODS: The clinical and radiographic results of the first 118 consecutive Oxford medial UKAs (OUKA) using a minimally invasive technique (phase 3) in 101 patients 60 years of age or younger at the time of surgery were evaluated. Median age at surgery was 57 (25-60) years. Kaplan-Meier survivorship analysis was used to estimate implant survival. RESULTS: Mean time of follow-up evaluation was five (SD 1.6) years. At final follow-up, three patients (three knees) had died, and two patients (three knees) were lost to follow-up. Five knees were revised: three for unexplained pain, one for early infection and one for bearing fracture. There was one impending revision for progression of osteoarthritis in the lateral compartment. The radiographic review demonstrated that 5 % of the knees had progressive arthritis in the lateral knee compartment, of those 2 % with full joint space loss and pain. The Kaplan-Meier survival analysis, using revision for any reason as the endpoint, estimated the five-year survival rate at 97 % (95 % CI 91-99). Ninety-six per cent of the non-revised patients were satisfied with the outcome, and 4 % were dissatisfied. The mean Oxford knee score was 41 (SD 7), with 6 % of the knees having a poor result. The mean AKSS was 89 (SD 14), mean flexion was 129° (SD 13) and the mean UCLA score was 6.8 (SD 1.5). CONCLUSION: Minimally invasive Oxford medial UKA was reliable and effective in this young and active patient cohort providing high patient satisfaction at mid-term follow-up. Progressive arthritis in the lateral knee compartment was a relevant failure mode in this age group. Most revisions were performed for unexplained pain, while we did not find loosening or wear in any patient. LEVEL OF EVIDENCE: IV.

Influence of surgical approach on component positioning in primary total hip arthroplasty.

BACKGROUND: Minimal invasive surgery (MIS) has gained growing popularity in total hip arthroplasty (THA) but concerns exist regarding component malpositioning. The aim of the present study was to evaluate femoral and acetabular component positioning in primary cementless THA comparing a lateral to a MIS anterolateral approach. METHODS: We evaluated 6 week postoperative radiographs of 52 hips with a minimal invasive anterolateral approach compared to 54 hips with a standard lateral approach. All hips had received the same type of implant for primary cementless unilateral THA and had a healthy hip contralaterally. RESULTS: Hip offset was equally restored comparing both approaches. No influence of the approach was observed with regard to reconstruction of acetabular offset, femoral offset, vertical placement of the center of rotation, stem alignment and leg length discrepancy. However, with the MIS approach, a significantly higher percentage of cups (38.5 %) was malpositioned compared to the standard approach (16.7 %) (p = 0.022). CONCLUSIONS: The MIS anterolateral approach allows for comparable reconstruction of stem position, offset and center of rotation compared to the lateral approach. However, surgeons must be aware of a higher risk of cup malpositioning for inclination and anteversion using the MIS anterolateral approach.

Minimum ten-year results of a 28-mm metal-on-metal bearing in cementless total hip arthroplasty in patients fifty years of age and younger.

PURPOSE: Concerns have been raised in relation to metal-on-metal (MoM) articulations with catastrophic soft-tissue reactions due to metal debris. We reviewed how small head MoM articulations perform in primary uncemented total hip arthroplasty (THA) in young patients at a minimum of ten years. METHODS: We retrospectively evaluated the clinical and radiographic results of the first 100 consecutive primary cementless THAs using the 28-mm Metasul MoM articulation in 91 patients younger than 50 years of age at the time of surgery. RESULTS: After 13 years, survival for the endpoint revision due to any reason was 90.9 % and 98.9 % for revision due to aseptic implant loosening. The cumulative incidence of MoM related revisions was 1.2 %. Small proximal femoral osteolysis was found in 18 % of hips. No acetabular osteolysis or loosening was detected. Two hips showed signs of femoral neck impingement with severe damage to the neck. CONCLUSIONS: Early in the second decade, MoM-associated complications were rare using the 28-mm Metasul articulation, and aseptic loosening was not a major mode of failure in this cohort of young patients. LEVEL OF EVIDENCE: Therapeutic Level IV.

Comparison of native anatomy with recommended safe component orientation in total hip arthroplasty for primary osteoarthritis.

BACKGROUND: The adverse consequences of impingement, dislocation, and implant wear have stimulated increasing interest in accurate component orientation in total hip arthroplasty and hip resurfacing. The aims of the present study were to define femoral and acetabular orientation in a cohort of patients with primary hip osteoarthritis and to determine whether the orientation of their native hip joints corresponded with established recommendations for implantation of prosthetic components. METHODS: We retrospectively evaluated a consecutive series of 131 preoperative computed tomography (CT) scans of patients with primary end-stage hip osteoarthritis (fifty-seven male and seventy-four female patients; mean age, sixty years). Patients were positioned according to a standardized protocol. Accounting for pelvic tilt, three-dimensional acetabular orientation was determined in the anatomical reference frame. Moreover, three-dimensional femoral version was measured. Differences in native anatomy between male and female patients were assessed with use of nonparametric tests. Native anatomy was evaluated with reference to the "safe zone" as described by Lewinnek et al. and to a "safe" combined anteversion of 20° to 40°. RESULTS: In the entire cohort, the mean femoral anteversion was 13° and the mean acetabular anteversion was 19°. No significant differences in femoral, acetabular, or combined (femoral and acetabular) anteversion were observed between male and female patients. The mean acetabular inclination was 62°. There was no significant difference in acetabular inclination between female and male patients. We did not observe a correlation among acetabular inclination, acetabular anteversion, and femoral anteversion. Ninety-five percent (125) of the native acetabula were classified as being within the safe anteversion zone, whereas only 15% (nineteen) were classified as being within the safe inclination zone. Combined anteversion was within the safe limits in 63% (eighty-three) of the patients. However, only 8% (ten) of the cases in the present cohort met the criteria of both "safe zone" definitions (that of Lewinnek et al. and combined anteversion). CONCLUSIONS: Acetabular anteversion of the osteoarthritic hip as defined by the native acetabular rim typically matches the recommended component "targets" for cup insertion. There was no specific relationship among native acetabular inclination, acetabular anteversion, and femoral anteversion. Neither native acetabular inclination nor native combined anteversion appears to be related to current implant insertion targets. CLINICAL RELEVANCE: The present findings of native acetabular and femoral orientation in patients with primary hip osteoarthritis support intraoperative component positioning for total hip arthroplasty.

Proximal femoral canal shape is more accurately assessed on AP hip radiographs than AP pelvis radiographs in primary hip osteoarthritis.

The objectives of the present study were to determine whether differences in the radiographic appearance of the of the proximal femoral canal exist on corresponding AP pelvis and AP hip radiographs, and whether radiographic assessment of canal shape is accurate with reference to computed tomography (CT). In a retrospective study, corresponding radiographs and CT scans of 100 consecutive patients with primary hip OA were evaluated. Active shape modelling (ASM) was performed to assess the variation in proximal femoral canal shape and to identify differences between AP hip and AP pelvis views. Differences in the medial cortical flare between radiographs and CT were quantified using least squares curve fitting. ASM identified significant differences in the assessment of canal shape on corresponding AP hip and AP pelvis views. Curve fitting demonstrated a good agreement between AP hip radiographs and CT. Agreement between AP pelvis radiographs and CT was less good. In contrast to AP pelvis radiographs, AP hip radiographs allow a more accurate and reliable assessment of proximal femoral canal shape in the frontal plane in primary hip OA. Our findings may improve stem fit in total hip arthroplasty without the routine use of CT.

Long-term (20- to 25-year) results of an uncemented tapered titanium femoral component and factors affecting survivorship.

BACKGROUND: Uncemented femoral components in primary total hip arthroplasty (THA) are commonly used today, but few studies have evaluated their survival into the third decade. QUESTIONS/PURPOSES: We evaluated (1) survivorship using femoral revision for any reason as the end point; (2) survivorship using femoral revision for aseptic loosening as the end point; and (3) patient-related and surgical risk factors for aseptic stem loosening at a minimum 20-year followup with an uncemented tapered titanium stem. METHODS: We reviewed the clinical and radiographic results of 354 THAs in 326 patients performed between January 1985 and December 1989 using an uncemented grit-blasted, tapered titanium femoral stem. Mean age at surgery was 57 years (range, 13-81 years). Kaplan-Meier survivorship analysis was used to estimate long-term survival. Minimum followup evaluation was 20 years (mean, 22 years; range, 20-25 years); at that time, 120 patients (127 hips) had died, and four patients (five hips) were lost to followup. Multivariate survival analysis using a Cox regression model was performed. RESULTS: Survivorship at 22 years with revision of the femoral component for any reason as the end point was 86% (95% confidence interval [CI], 81%-90%). Survivorship for femoral revision for aseptic loosening as the end point was 93% at 22 years (95% CI, 90%-96%). Undersized stems (canal fill index≤80%) and stems in hips with cup revision were at higher risk for aseptic loosening (hazard ratio, 4.2 and 4.3, respectively). There was a high rate of acetabular revision in this series (38%), mostly related to smooth-threaded, cementless sockets. CONCLUSIONS: Uncemented femoral fixation was reliable into the third decade. Age, male sex, and diagnosis were not associated with a higher risk of aseptic loosening. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Influence of surgical approach on postoperative femoral bone remodelling after cementless total hip arthroplasty.

We retrospectively evaluated the femoral periprosthetic bone mineral density (BMD) in a consecutive series of patients who had undergone total hip arthroplasty (THA) with a straight, double tapered cementless stem using a muscle-sparing anterolateral (group A) and the transgluteal (group B) surgical approach. Dual-energy x-ray absorptiometry (DXA) measurements were performed in the first postoperative week (t1), and after 3 (t2), 6 (t3) and 12 months (t4) using an identical protocol. Patients were clinically and radiographically evaluated at final follow-up (t4). A complete set of four consecutive DXA measurements was obtained for 16 hips in group A and 26 hips in group B. In patients in whom the transgluteal approach was used (Group B), we observed a significantly greater decline in overall periprosthetic BMD (netavg) and in BMD in the periprosthetic regions of interest (ROI) 1, 4, 5 and 6 between t1 and t4. At clinical and radiographic evaluation at t4, no differences between the groups were detected. Femoral periprosthetic BMD is affected by the selected surgical approach in the first postoperative year. This might be attributed to altered femoral loading as a result of differences in intraoperative damage to the abductor muscles.

Long-term results of cementless femoral reconstruction following intertrochanteric osteotomy.

PURPOSE: The objective of this retrospective cohort study was to assess the long-term outcome of cementless femoral reconstruction in patients with previous intertrochanteric osteotomy (ITO). METHODS: We evaluated the clinical and radiographic results of a consecutive series of 45 patients (48 hips, mean age 50 years) who had undergone conversion hip replacement following ITO with a cementless, grit-blasted, double-tapered femoral component. Clinical outcome was determined using the Harris hip score. Stem survival for different end points was assessed using Kaplan-Meier survivorship analysis. RESULTS: At a mean follow-up of 20 (range, 16-24) years, 11 patients (12 hips) had died, and no patient was lost to follow-up. Six patients (six hips) underwent femoral revision, two for infection, three for aseptic loosening and one for periprosthetic fracture. Mean Harris hip score at final follow-up was 78 points (range, 23-100 points). Stem survival for all revisions was 89% (95%CI, 75-95) at 20 years, and survival for aseptic loosening was 93% (95%CI, 80-98). CONCLUSIONS: The long-term results with this type of cementless femoral component in patients with previous intertrochanteric osteotomy are encouraging and compare well to those achieved in patients with normal femoral anatomy.

High survival in young patients using a second generation uncemented total hip replacement.

PURPOSE: Whilst excellent long-term results with contemporary uncemented stems have been reported for total hip arthroplasty in young patients, the survival rates for the whole reconstruction are often compromised by high failure rates on the acetabular site due to peri-acetabular osteolysis and accelerated wear. METHODS: In patients 60 years old or younger, we retrospectively reviewed the results at a minimum of ten years of 89 consecutive uncemented total hip replacements in 88 patients using the press-fit Fitmore acetabular component in combination with the CLS Spotorno stem and a 28-mm Metasul metal-on-metal articulation or a 28-mm alumina ceramic on conventional polyethylene bearing. The mean age at the time of surgery was 49 years (range, 25-60). The mean clinical and radiological follow-up was 12 years (range, 10-15). RESULTS: Six patients (six hips) died and two patients (two hips) were lost to follow-up. Five hips were revised: one for deep infection, one for peri-prosthetic femoral fracture, and one for aseptic stem loosening. In two hips an isolated revision of the acetabular liner was performed (one for recurrent dislocation and one for unexplained pain). No revision was performed for accelerated wear, osteolysis or aseptic loosening of the acetabular shell. We could not detect peri-acetabular osteolysis visible on plain radiographs in those hips evaluated radiographically. The Kaplan-Meier survival with revision for any reason as the endpoint was 94% (95% confidence interval, 86-97) at 12 years. CONCLUSIONS: The survival rates and the radiological outcomes with this implant combination in this young and active patient group are encouraging when compared to the results reported for other uncemented cups in this age group.

Correlation of positioning and clinical results in Oxford UKA.

In a prospective clinical study, 59 patients with anteromedial osteoarthritis of the knee (61 knee joints) underwent minimally invasive medial Oxford unicompartmental arthroplasty phase 3. Clinical and radiographic examinations of 56 knees were carried out at five (4-7) years. American Knee Society (AKS) scores improved from mean 45.5 (20-80) points (knee score) and 55 (15-100) points (function score) before surgery to 90 (30-100) points in both scores after surgery. The position of each implant was determined on screened radiographs using an image intensifier. The implant position was analysed according to the Oxford X-ray rating system. We evaluated nine measures, and there was no detectable correlation between implant position and clinical result. However, long-term studies are needed before it is possible to elaborate an evidence-based guideline on positioning.

Complications in shoulder arthroplasty: an analysis of 485 cases.

The aim of this study was to analyse the complication rates of six different shoulder arthroplasty concepts for different diagnoses in the short and midterm. The study included 485 primary shoulder arthroplasties. The mean follow-up of the cohort was 3.5 (1-10) years. Complications were classified into three categories: (1) without reoperation, (2) soft tissue revision and (3) implant revision. In total, 56 complications were recorded (11.6%): 34 (7%) were category 1 complications, 11 (2.3%) were category 2 and 11 (2.3%) were category 3. For the whole cohort the median follow-up was 1.6 years (1-10 years) and the survival rate without any complication was 90.5% (95% CI: 87.9-93.1). Patients rated the result of their surgery in 270 (55.7%) cases as very satisfied, in 148 (30.5%) as satisfied, in 43 (8.9%) as somewhat disappointed and in 24 (4.9%) as disappointed. A relatively low complication rate was found in this study. Long-term observations are necessary to confirm these results.

Long-term results of hip arthroplasty in ambulatory patients with cerebral palsy.

Osteoarthritis (OA) secondary to dislocation and dysplasia is a common problem in patients with cerebral palsy. The purpose of this study was to evaluate the results of total hip replacement (THR) in ambulatory patients with cerebral palsy. Eighteen total hip arthroplasties were performed in 16 ambulatory patients with cerebral palsy. The patient's mean age at surgery was 42 +/- 8 years (range 32-58 years), and the mean follow-up was 10 +/- 6 years (range 2-18 years). Data were obtained by a standardised telephone interview. There was a significant postoperative reduction in pain on the NAS (narrative analogue scale) from 8.4 preoperatively to 1.1 postoperatively (p = 0.002). At follow-up no stem had been revised. Three cups were revised for aseptic loosening at two and six years, and one cup was revised for recurrent dislocation of the hip. One hip was revised for infection 12 years after the index surgery. One hip dislocated (three months postoperatively) and was treated by closed reduction. In ambulatory patients with cerebral palsy and secondary osteoarthritis of the hip THR can provide long-term pain relief and improved function. The rate of long term complications was moderate in this series; however, the dislocation rate was higher than in standard OA cases.

Long-term results of the threaded Weill cup in primary total hip arthroplasty: a 15-20-year follow-up study.

Uncemented, threaded acetabular components with smooth surface treatment were widely used in continental Europe in the 1970s and 1980s for primary total hip arthroplasty (THA). Previously published studies showed high failure rates in the mid-term. In a consecutive series of 116 patients, 127 threaded cups with smooth surface treatment (Weill cup; Zimmer, Winterthur, Switzerland) were implanted in combination with one type of uncemented stem. Patients were followed up clinically and radiographically. Mean time of follow-up was 17 years (range 15-20). At the time of follow-up, the acetabular component had been revised or was awaiting revision in 30 hips (24%). Two hips were revised for infection and 23 for aseptic loosening. Four polyethylene liners were exchanged because of excessive wear. One hip was awaiting revision. The survival rate for all acetabular revisions including one hip awaiting revision was 75% (95%CI: 65-85%) at 17 years. These results support the view that smooth, threaded acetabular components do not provide satisfactory long-term fixation and should be abandoned. It is important to closely monitor patients with these components as the failure rate remains high in the long-term.

Long-term results of the threaded Mecron cup in primary total hip arthroplasty : A 15-20-year follow-up study.

In the 1970s, high failure rates of cemented acetabular components, especially in young patients, in the middle- and long-term prompted a search for alternatives. The Mecring was one of the most popular first generation uncemented, threaded cups widely used in the 1980s for arthroplasty of the hip. First generation threaded cups commonly had smooth surface treatment and showed unacceptably high failure rates in the mid-term. In a consecutive series of 209 patients, 221 threaded uncemented acetabular cups with smooth surface treatment (Mecring) had been implanted in combination with one type of uncemented stem. Patients were followed up clinically and radiographically. The mean time of follow-up was 17 (range 15-20) years. In 91 (41%) hips the acetabular component had been revised or was awaiting revision: two hips for infection and 84 (38%) for aseptic loosening. Five hips were awaiting revision. The survival rate for all revisions including hips awaiting revision was 49% (95% CI: 41-57%) at 17 years. These results support the view that smooth, threaded acetabular components do not provide satisfactory long-term fixation and should be abandoned. Patients with these components must be closely monitored as the failure rate remains high in the long-term.

Survival of the cementless Spotorno stem in the second decade.

High survival rates have been reported for the uncemented CLS Spotorno stem up to 10 years. To confirm survival at longer followup we report the minimum 15-year (mean, 17 years; range, 15-20 years) for 257 hips using this stem. We retrospectively evaluated the clinical and radiographic results of all 326 patients (354 THAs) operated between 1985 and 1989. The patients had a mean age of 57 years using an uncemented grit-blasted, tapered titanium femoral stem. Eighty-six patients (89 hips) died and eight patients (eight hips) were lost to followup, leaving 240 patients (257 hips) for evaluation. The femoral component was revised in 35 hips: eight for infection, nine for periprosthetic fracture, one for traumatic loosening, and 17 for aseptic loosening. Survival of the stem was 88% at 17 years (95% confidence interval, 84%-92%), and survival with femoral revision for aseptic loosening as an end point was 94% (95% confidence interval, 91%-97%). The median Harris hip score at followup was 80 points. No thigh pain was reported. Small osteolytic lesions (< 1 cm(2)) were found in the proximal Gruen zones (1 or/and 7) in 28 hips (15%). No distal femoral osteolysis was found. The long-term survival with this type of femoral component remains high in the second decade.