Introduction: Revision surgery for stem loosening and peri-implant bone loss of variable extent is a major challenge for orthopedic surgeons. Our strategy has been to use cementless straight stems of rectangular cross-section for revisions. To ascertain the value of this implant we analyzed the results at a minimum follow-up of 10 years.

Material and Method: Between October 1991 and end 1998, 125 patients (134 hips) underwent revision surgery. Of these, 39 were males and 86 were females. Sixty-seven of the original implants were cemented and as many were cementless. Cementless revision stems (SLR; Plus Orthopedics, Aarau, Switzerland) size 3 to 11 (180 to 223 mm in length) were used for revisions. Patient age at the time of surgery was 37.8 to 89.3 (mean, 71.0) years.

Fifty patients (53 hips) died post revision 0.0 to 13.5 (mean, 6.8) years. Their implants had been followed-up radiographically for 0.0 to 9.2 (mean, 3.6) years. At the time of revision these patients had been 48.9 to 89.3 (mean, 76.7) years old. One of them had undergone stem revision for aseptic loosening one year post surgery. Another 6 were revised 1.4 to 13.9 years post surgery, 5 for low grade infection and 1 for peri-implant fracture.

Seven patients refused to present for follow-up because of advanced age and poor cooperation. Eight were contacted by telephone. These 15 patients were not re-operated. Five patients were altogether lost to follow-up, thus leaving a total of 53 hips (49 patients) for analysis at a follow-up time of at least 10 years. The follow-up time was 10.0 to 16.1 (mean, 11.6) years.

For radiographic follow-ups monitor-guided a.-p. and axial radiographs were recorded. These were analyzed by Gruen zones.

Results: All stems were properly aligned along the long femoral axis, except in 1 patient, who had sustained a peri-implant fracture during a fall with axial stem subsidence responding to conservative treatment. In 38 patients peri-implant bone apposition was detected in all 7 Gruen zones. This was combined with bone resorption in other zones in 2 patients. Four patients presented with osteolytic lesions. In one of them with metal-on-metal articulating surfaces, the lesion extended to several segments and will necessitate revision. All other stems were stable. None of them was at risk.

Conclusion: This analysis showed that the SLR revision stem performs well for an intermediate follow-up time of at least 10 years.

Intruduction: Cementless cup anchorage for total hip replacement is among the techniques widely accepted today. Attention focuses on hemispheric cups mimicking the anatomical shape of the bony acetabulum. However, the first-generation cementless hemispheric cups had a number of design flaws, which have meanwhile been attended to. We therefore never really turned away from threaded cups and began to implant a cone-shaped version of commercially pure titanium in January 1985. Introduced in January 1993, the redesigned version was unlike any other implant described in the literature in terms of its outer shape, the locking mechanism for the polyethylene liner, the cutting strength of its teeth and the thin wall of the cup shell. We wanted to know whether this implant was generally applicable for all primary THRs irrespective of the underlying anatomy, i.e. whether the exclusive consecutive use of this implant was justified.

Method: Between 1/1/1993 and 30/4/1994, 332 patients underwent primary surgery for osteoarthritis with threaded cups and titanium stems. These self-tapping double-cone cups made of pure titanium feature sharply cutting teeth for anchorage without screws. The PE liner locks into the titanium shell by a 4-level conical locking mechanism obviating the need for indentations for rotational adjustment of the liner. All cups and stems implanted during this period were uncemented. At 10 years plus, clinical and monitor-controlled radiologic follow-ups were conducted to evaluate changes in cup position, radiolucent lines, osseo-integration and revisions.

Results: 209 patients (63 males and 146 females; mean age at surgery: 62.6 years, range: 18.9 to 83.2 years) showed up for follow-up. 71 were dead, 36 without revisions were contacted by phone, 10 were lost to follow-up. The mean follow-up time was 10.2 years (range: 10.0 to 11.1 years). 2 patients had undergone cup revision, one for low-grade infection after 9.6 years and one for cup fracture after 5 years. With cup revision as the endpoint, the Kaplan-Meier survival rate was 99,2 % (CI: 96.6 to 99.8). Radiography showed altered cup inclination in two patients and radiolucent lines signalling absence of osseointegration in one patient. All other implants were stable clinically and radiologically. Gaps between the cup floor and the bone tended to be spontaneously obliterated by newly formed bone. Complete obliteration was observed even in cases with incomplete cranial implant coverage due to hip dysplasia.

Conclusion: The outcome of threaded double-cone cups at 10 years and more compares well with the best results achieved with other implants, particularly hemispheric cups. This documents that their unique design features have so far stood the test of time. It also shows that these cups have a place in all patients candidates for primary total hip arthroplasty.

Introduction: Cementless tapered straight stems of the first generation were introduced in 1979, those of the second generation in 1986. For further perfection SL-PLUS stems were introduced in early 1993. These were redesigned proximally and featured slimmer necks for a larger range of motion, a central trochanteric pull-out thread and a larger surface area in the proximal stem third.

Method: Between 01/01/1993 and 31/03/1994 339 patients were implanted with these cementless new-generation stems. In the period under review no stems other than these, e.g. cemented implants or other implant systems, were used in primary THAs.

Of the 339 patients, 218 were available for follow-up, 72 had died, 38 without revision surgery were contacted by phone and 11 were lost to follow-up.

The underlying pathology was idiopathic degenerative joint disease (153 pts.), dysplastic OA (37 pts.), femoral head necrosis (12 pts.), posttraumatic OA (6 pts.) and OA of other origins (5 pts.). To evaluate changes in stem position, radiolucent lines, osseointegration and revision, clinical and monitor-controlled radiographic follow-ups were conducted at 10 years plus.

Results: 5 patients were revised within the follow-up time because of: one aseptic loosening, one low-grade infection, two periprosthetic fractures, one traumatic subsidence.

At the 10 year follow-ups (10,0 to 11,1, mean 10,2 years) the stem position was unchanged in all of the 213 patients. The stems had been implanted in proper anatomical alignment in 196 patients, in varus in 16 and in valgus in one patient. 93 patients showed no changes of the peri-implant bone. In 96 peri-implant bone apposition was recorded in one or more zones (Gruen). 20 patients presented with radiologic evidence of both peri-implant bone apposition and some atrophy. None of these patients showed abnormalities clinically (HHS: 95.2; 76–100). At the 10-year follow-ups 2 stems had worked loose. Another 2 patients presented with intertrochan-teric osteolyses with definite progression versus the 5-year follow-up. On analysis, radiolucent lines (RLs) were seen in zone 1 in 28.6% of cases, in zones 2 and 6 in 3.3%, in zones 3, 4 and 5 in 0.5% and in zone 7 in 22.1%.

The Kaplan-Meier survival rate was 98.2% (CI 95.3 to 99.2) with revision of the stem for any reason as the end point (N = 339).

Conclusion: The outcome of this quality control study showed the stem to be universally applicable in all primary THAs so that its continued use in the indications listed is well justified.

Introduction: Stable cup anchorage in dysplastic hips is a key problem of THA. The pupose of this study was to evaluate the usefulness of a cementless cup without acetabuloplasty based on medium term Results: Method 53 patients, 47 females and 6 males aged 20 to 76 (mean 49) years at surgery were followed-up after 4.9 to 11.4 (mean 8.8) years. Crowe’s dysplasia classification showed 30 hips to be grade I, 23 grade II and 1 grade III pre-operatively. All patients were implanted with threaded pure-titanium double-cone cups. Acetabuloplasty was omitted and care was taken to achieve primary stability in the bone stock available. Pre-operative leg length discrepancy versus contralateral was 0 to 7 (mean 3.9) cm.

Results: On postoperative radiography 45 cups were completely covered by bone in position I. Of 6 cups 3 quarters were covered, of 1 cup 2 thirds and of another one ½ of the cranial circumference. All of the incompletely covered cups were stable at follow-up. Altogether 51 cups had maintained their position by radiographic evidence and were firmly anchored in bone. Cup loosening in Crowe grade I and II necessitated 2 revisions. Leg length was equalized in 39 patients with mean lengthening by 3.4 (1.2 to 4.5) cm.

Conclusion: In the management of dysplastic hips the system used provides stable anchorage in the bone stock without additional acetabuloplasty. Even pronounced soft tissue tension on substantial leg lengthening does not impair implant stability.

Summary: Primary stable implantation of a cementless titanium cup in hip dysplastia cases without additional acetabuloplasty is achieving good medium term results.

Although good clinical results for modern metal-on-metal total hip endoprostheses are reported, in some cases early loosening is encountered. Such loosening may lead to revision surgeries, which raise some concern on the functionality of that pairing. The study contains 17 early-revised uncemented metal-on-metal (Co28Cr6Mo, ASTM F799) total hip arthroplasties from one manufacturer (Plus Endoprothetik, Switzerland) with a mean of 29 months in-situ (12–58) from 16 patients (seven male, nine female); mean age at revision surgery was 57 years (41–72). The reason for revisions was aseptic loosening of implants with increasing pain (13 stems and seven metal cups were revised). The tribologic assessment of all 17 metal pairings is conducted by 3 dimensional measurements of the metal ball heads and inlays according to ISO and through scanning electron microscopy (SEM) inspection of the articulating surfaces. Additional metal ion content (Cr, Co, Mo, Ti,Al, Nb, Ni) of selected tissue samples and synovial fluid is quantified by inductively coupled plasma – atomic emission spectrometry (ICP-AES).

The mean wear rate of both, the femoral ball head and the acetabular inlay, is 7.3um/a (2.8 – 29.4) based on the time in-situ with a mean clearance of 42.8um (32 – 56um). Adhesive and abrasive wear traces as well as third body wear particles (aluminum oxide Al2O3) are identified on all bearing surfaces only to an extent, which is typical for metal pairings. Corrosive attack is visible on one pairing as a smoky area.

Tribologic results do not indicate a significant contribution of wear due to the Al2O3-particles. The amount of wear does not seem increased and is comparable to previously published data for metal-on-metal pairings and simulator studies. Analytic results indicate a relatively high Al content from all retrieved tissue areas. The investigations on the surfaces of all 17 metal-on-metal articulations indicate no material failure that might have led to the necessity of early revision.

Patients with hip dysplasia that are to be managed with total hip replacement constitute a special group of arthroplasty candidates. Each patient will need to be treated according to his or her anatomical pattern. The important point to remember is that dysplasia in itself is not a contraindication to cementless hip replacement. However, there are certain points that need to be taken into account in the management of this special patient population.

The surgical technique must be appropriate; in particular, cup medialisation is an important feature. The implant system used should be modular so as to permit a large number of combinations, and it also should provide cups for hard bone and cups for soft (osteoporotic) bone, as well as anti-dislocation inserts. Such a system will also allow limb length to be corrected, usually without reference to the centre of rotation of the hip joint. The primary objective is the positioning of the cup in the native bone stock at a site that will ensure optimum primary stability. If an adjunctive shelf procedure is considered necessary, any buttressing done will have to be performed after the cup itself has been stably implanted.

In our centre between 1993 and 1995, 122 were patients with dysplastic hips. One hundred and eleven of these hips were clinically and radiologically followed-up by the author. Mean follow-up was 4.1 years (range 2.1 to 6.1 years). Typically, there were more women than men: 88 cups were implanted in female patients and 23 in male patients. The average age at surgery was 53 years. The youngest patient in the series was 19 years of age and the oldest was 77. Coxa vara osteochondritica (25 cases) was treated as a separate diagnostic and management group. In 17 cases previous acetabuloplasties had been done, usually a Chiari osteotomy. In terms of severity of the dysplasia, 67 hips were Grade I, 36 were Grade II, and eight were Grade III according to Randelli.

All patients were managed with our biconical threaded cup made of commercially pure titanium. In 91 cases the Standard version, designed for use in normal or in hard bone, was employed. The Porosis type of cup, with a 46% greater thread surface area, was chosen in 20 cases. Antidislocation inserts were used in two cases. Conical cups are inserted with prestress and do not therefore require additional fixation with screws or lugs. The most important instrument for the achievement of optimum implant positioning is the medialising reamer with an aggressive front-cutting action. The use of this instrument allows sufficient bony coverage to be obtained to allow fixation of the titanium cup in the host bone with a good primary stability.

The following standard radiographs were used in the analysis: (1) AP view of the operated hip and the contralateral hip; (2) AP and axial views of the operated femur; (3) monitor-controlled AP view of the cup. In 110 cases the position of the cup had not changed during the follow-up period and cranial migration was seen in one case. This case and an additional one were judged to be “at risk” since the patients were pain-free and the position of the implants had remained unchanged for the past two years. These two patients also had more than 2 mm Zone III lucencies. In both cases a superior (Zone I) sclerotic area was found to have developed postoperatively. This pattern differed from the one observed in patients with stable implants, in whom the extent of preoperative sclerosis was significantly reduced following arthroplasty. This regression of sclerosis around a stable implant suggests that the implantation of the titanium cup results in an improvement of the periacetabular stress pattern. In 84 cases there was evidence of increasing integration of the implant; in 22 cases no bony response could be detected, i.e., there was neither apposition of new bone nor loss of existing bone stock. In one case part of the rim of the titanium cup was found to have broken off superiorly. This patient has been recently revised with an exchange of the cup. At revision the cup was found to be so soundly osseointegrated to the extent that it could be removed only after being cut up with a diamond tool. None of the other patients have required revision to date, and none are scheduled for revision as a result of follow-up.