Original Article
Long-term Results of the Cementless ALLOCLASSIC Hip Arthroplasty System Using a 28-mm Ceramic Head: With a Retrospective Comparison to a 32-mm Head

https://doi.org/10.1016/j.arth.2005.08.027Get rights and content

Abstract

One hundred twenty-four total hip arthroplasties in 119 patients, all performed with the cementless ALLOCLASSIC hip arthroplasty system (SL stem and CSF cup; Centerpulse, Winterthur, Switzerland), were analyzed retrospectively. In all hips, a 28-mm head and an ultrahigh–molecular-weight polyethylene inlay were used. Of the 124 hips, 81 could be investigated clinically and radiologically after an average of 150.6 months (range, 133-169 months). Twenty-six patients (26 hips) died in the interim. One of these patients had septic cup loosening. Seventeen hips (16 patients) were not available for follow-up because of health reasons (12 hips in 11 patients), lack of cooperation (3 hips in 3 patients), or loss to follow-up (2 hips in 2 patients). Of the 124 total hip arthroplasties, 4 cups were removed (2 aseptic and 2 septic loosening). No stem had to be removed. If aseptic loosening is defined as the end point, the survival rate is 98.4% (95% confidence interval, 93.8%-99.6%) for the cup and 100% for the stem after 157 months. If revision for any reason is defined as the end point, the survival rate is 95.6% (95% confidence interval, 90.1%-98.3%). Before operation, the average Harris Hip Score was 36.4 points (21-46). At time of follow-up, the average Harris Hip Score was 89.7 points (54-100). Radiolucent lines and osteolyses were found only seldom (mostly in the proximal stem zones).

Section snippets

Material and Methods

The ALLOCLASSIC CSF cup is manufactured of pure titanium. Its shape is conical. On the outer surface, self-cutting lamella threads are responsible for the primary stability of the shell during implantation. Polyethylene inlays are inserted into the cup and are fixed by a self-locking mechanism.

The ALLOCLASSIC SL stem has a rectangular cross-section, which provides a high rotational stability. Furthermore, it makes an extended removal of the endostium of the femur during implantation

Clinical Results

Before surgery, the HHS was on average 36.4 points (median, 36 points; minimum, 21; maximum, 46). At time of follow-up, the HHS was on average 89.7 points (median, 94 points; minimum, 54; maximum, 100). Thus, the HHS was increased on average by 53.3 points.

Before operation, 78 hips (100.0%) had severe pain. At time of follow-up, 61 hips (78.2%) were pain-free, 12 hips (15.4%) showed minimal pain, and 5 (6.4%) showed slight pain.

Radiologic Results

Ectopic ossification was found in 32 (41.0%) hips. Ossification

Discussion

One of the most important parameters in THA is the survival rate. Because the different frequently used implants nowadays provide already very good results, long-term follow-ups are necessary to rate the reliability of the prosthesis. In this series, we analyzed 78 hips clinically and radiologically after an average of 150.6 months. With a survival rate of 100% for the ALLOCLASSIC SL stem and 98.4% for the CSF cup after 157 months (end point aseptic loosening), results using this system are

Conclusion

The survival rate as well as the clinical and radiologic outcome of the ALLOCLASSIC SL stem and CSF cup in conjunction with a 28-mm ceramic ball head after 157 months is very good (Fig. 6). Keeping the restriction of a retrospective analysis in mind, the comparison to the 32-mm head shows a smaller number of radiolucent lines and osteolyses. However, the survival rate of the CSF cup was not improved. Longer follow-up studies for both the 32- and the 28-mm ceramic head might indicate whether the

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    No benefits or funds were received in support of the study.

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