Cluster hole versus solid cup in total hip arthroplasty: a randomized control trial

Are additional screws required for press-fit fixation of cementless acetabular cups? A systematic review and meta-analysis

Background

Press-fit cementless acetabular cup is widely used in total hip arthroplasty (THA). However, the use of additional screws for the acetabular cup has been extensively debated. The purpose of this review is to compare the stability, revision rate, wear rate, and clinical scores of cementless acetabular cups with and without screws in THA.

Materials and Methods

Comprehensive literature searches of the following databases were performed: Cochrane Library, Pubmed, Web of Science, OVID, Elsevier ClinicalKey, Clinicaltrials.gov, and EMBASE. We searched for trials that compared cementless acetabular cups with screws or without screws, and were published in the English language. We evaluated the stability of the prosthesis by osteolysis and migration. The clinical scores included Harris hip scores (HHS) and pain scores.

Results

Nineteen articles involving 4046 THAs met the inclusion criteria. Our analysis revealed that additional screws did not increase the stability of acetabular cups, and there was no statistical significance between the groups with and without screws in osteolysis and clinically relevant migration. Revision rates showed no significant difference between the groups with and without screws. There was no difference in wear between the two groups. Our analysis showed no difference in pain scores and HHS between groups.

Conclusion

Press-fit without screws could achieve sufficient acetabular cup stability. Acetabular cups without screws showed no difference from acetabular cups with screws in many outcomes. Additional screws are not required for cementless acetabular cups.

Level of evidence: Level III.

Acetabular screws do not improve early revision rates in primary total hip arthroplasty. An instrumented registry analysis

BACKGROUND

Initial stability of uncemented acetabular components in total hip arthroplasty (THA) is important for osseointegration and potentially enhanced by screw fixation. We used Australian Orthopaedic Association National Joint Replacement Registry data to determine whether screw usage influences uncemented acetabular component survival.

METHODS

Primary THA with uncemented acetabular components performed for osteoarthritis from 1999 to 2018 was included. Survivorship was calculated using Kaplan-Meier estimates of cumulative percent revision (CPR). Comparisons used Cox proportional hazards method. An instrumental variable analysis adjusted for surgeon preference for screws as a confounding factor was used.

RESULTS

Three hundred thirty thousand one hundred ninety-two THAs were included (31.8% with screws, 68.2% without). Two hundred twenty thousand six hundred seven were included in the instrumental variable analysis. Revision rate of acetabular components (all causes) was higher with screws during the first six years (hazard ratio (HR) = 1.45 (95% CI 1.34, 1.57), p < 0.001) and lower thereafter (HR = 0.81 (95% CI 0.67, 0.98), p = 0.027). Revision rate of acetabular components for loosening was higher with screws over the entire study period (HR = 1.73 (95% CI 1.51, 1.98), p < 0.001). Overall THA revision rate was higher with screws during the first six years (HR = 1.20 (95% CI 1.15, 1.26), p < 0.001) but lower thereafter (HR = 0.89 (95% CI 0.81, 0.98), p = 0.020). Revision rate for dislocation was higher with screws over the entire period (HR = 1.16 (95% CI 1.06, 1.26), p < 0.001). Instrumental variable analysis revealed higher revision rates with acetabular screws in the first six years. (HR = 1.18 (95% CI 1.09-1.29), p < 0.001).

CONCLUSION

Screws did not confer a protective effect against acetabular loosening and were not associated with long-term negative consequences.

Do screws and screw holes affect osteolysis in cementless cups using highly crosslinked polyethylene? A 7 to 10-year follow-up case-control study

BACKGROUND

The use of screws and the presence of screw holes may cause acetabular osteolysis and implant loosening in cementless total hip arthroplasty (THA) using conventional polyethylene. In contrast, this issue is not fully understood using highly crosslinked polyethylene (HXLPE), particularly in large comparative study. Therefore, we performed a case-control study to assess the influence of screw usage and screw holes on: (1) implant fixation and osteolysis and (2) polyethylene steady-state wear rate, using cases with HXLPE liners followed up for 7-10 years postoperatively.

HYPOTHESIS

The screw usage and screw holes adversely affect the implant fixation and incidence of wear-related osteolysis in THA with HXLPE.

PATIENTS AND METHODS

We reviewed 209 primary cementless THAs performed with 26-mm cobalt-chromium heads on HXLPE liners. To compare the effects of the use of screws and the presence of screw holes, the following groups were established: (1) with-screw (n=140); (2) without-screw (n=69); (3) no-hole (n=27) and (4) group in which a cup with screw holes, but no screw was used (n=42). Two adjunct groups (no-hole cups excluded) were established to compare the differences in the two types of HXLPE: (5) remelted group (n=100) and (6) annealed group (n=82). Implant stability and osteolysis were evaluated by plain radiography and computed tomography. The wear rate from 1 year to the final evaluation was measured using plain X-rays and PolyWare Digital software.

RESULTS

All cups and stems achieved bony fixation. On CT-scan, no acetabular osteolysis was found, but there were 3 cases with a small area of femoral osteolysis. The mean steady-state wear rate of each group was (1) 0.031±0.022, (2) 0.033±0.035, (3) 0.031±0.024, (4) 0.029±0.018, (5) 0.030±0.018 and (6) 0.034±0.023mm/year, respectively. A comparison of the effects of screw usage or screw holes found no significant between-group differences in the implant stability, prevalence of osteolysis [no acetabular osteolysis and 3/209 at femoral side (1.4%)] and steady-state wear rate.

DISCUSSION

This study suggests that there are no adverse effects on the results of THA with HXLPE from the use of cups with screw holes and the use of screws for cup fixation.

LEVEL OF EVIDENCE

Level III retrospective case-control study.

Solid Cup vs Cluster Hole in Total Hip Arthroplasty: A 10-Year Randomized Control Trial

BACKGROUND

Acetabular osteolysis is a major complication of total hip arthroplasty. It is caused in part by wear debris. It has been suggested that this debris can migrate through screw holes in the acetabular component. Solid-backed components have been used to prevent this migration and reduce osteolysis. Newer materials, however, have reduced wear debris. This study aimed to evaluate whether using solid-backed instead of cluster-hole components actually reduces osteolysis. This could open up the possibility of screws being used for greater stability where required.

METHODS

This prospective trial randomized 100 patients undergoing cementless total hip arthroplasty to receive either cluster-hole or solid-backed acetabular components. A cementless cup and highly cross-linked polyethylene was used in all patients. Computed tomography, performed at 5 and 10 years after surgery, was assessed by a blinded radiologist for the presence of osteolysis.

RESULTS

Of the 100 patients, 14 required screws for stability, and so were moved into a third "screw" group for per-protocol analysis. At 10 years after surgery, osteolytic lesions were discovered in 18.2% of patients. There was no difference in incidence or volume of osteolysis between patients with cluster-hole acetabular components and those with solid-backed components.

CONCLUSION

This study reveals a low number of patients with osteolytic lesions 10 years after total hip arthroplasty performed with a modern cup design and highly cross-linked polyethylene liner. There was no clear benefit to using solid-backed acetabular components. Cluster-hole components, however, offer the option of screw augmentation when required.

The Relationship Between Polyethylene Wear and Periprosthetic Osteolysis in Total Hip Arthroplasty at 12 Years in a Randomized Controlled Trial Cohort

BACKGROUND

Polyethylene acetabular components are common in hip arthroplasty. Highly cross-linked polyethylene (HXLPE) has lower wear than ultra-high molecular weight polyethylene (UHMWPE). Evidence suggests that wear particles induce inflammation causing periprosthetic osteolysis contributing to implant loosening with wear rates of 0.05 mm/y were considered safe. We aimed to compare incidence and volume of periacetabular osteolysis between HXLPE and UHMWPE using computed tomography.

METHODS

Initially, 54 hips in 53 patients were randomized to HXLPE or UHMWPE acetabular liner. At 10 years, 39 hips in 38 patients remained for the radiostereometric analysis' demonstrating significantly lower wear in the HXLPE group. At 12 years, 14 hips in 13 patients were lost to follow-up leaving 25 hips for computed tomography assessment. Images were reconstructed to detect osteolysis and where identified, areas were segmented and volumized.

RESULTS

Osteolysis was observed in 8 patients, 7 from the UHMWPE group and only 1 from the HXLPE group (Fisher exact, P = .042). There was no correlation between the amount of polyethylene wear and osteolysis volume; however, the radiostereometric analysis-measured wear rate in patients with osteolysis from both groups was significantly higher than overall average wear rate.

CONCLUSION

This data demonstrates lower incidence of periacetabular osteolysis in the HXLPE group of a small cohort. Although numbers are too low to estimate causation, in the context of lower wear in the HXLPE group, this finding supports the hypothesis that HXLPE may not elevate osteolysis risk, and hence does not suggest that HXLPE wear particles are more biologically active than those generated by earlier generations of polyethylene.