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Evidence summaries

Mobile Bearing Vs Fixed Bearing Prostheses for Total Knee Arthroplasty

In patients with osteoarthritis, mobile bearing prostheses appear to have similar effects on knee pain, clinical and functional scores, health-related quality of life, revision surgery, mortality, reoperation rate and other serious adverse events compared with fixed bearing prostheses in posterior cruciate retaining TKA. Level of evidence: "B"

The quality ov evidence is downgraded by study quality

Summary

A Cochrane review [Abstract] 1 included 19 studies with a total of 1641 subjects (1616 with OA (98.5%) and 25 with RA (1.5%)) and 2247 knees.

Knee pain No statistically significant differences between groups were reported (SMD 0.09, 95% CI -0.03 to 0.22, P value 0.15). This represents an absolute risk difference of 2.4% points higher (95% CI 0.8% lower to 5.9% higher) on the KSS pain scale and a relative percent change of 0.22% (95% CI 0.07% lower to 0.53% higher), 11 studies and 1531 knees.

Clinical and functional scoresThe KSS clinical score did not differ statistically significantly between groups (14 studies and 1845 knees) with a MD of -1.06 points (95% CI -2.87 to 0.74, P value 0.25). KSS function was reported in 14 studies with 1845 knees as an MD of -0.10 point (95% CI -1.93 to 1.73, P value 0.91). In two studies (11%), the KSS total score was favourable for mobile bearing (159 vs 132 for fixed bearing), with MD of -26.52 points (95% CI -45.03 to -8.01, P value 0.005), but with a wide 95% CI indicating uncertainty about the estimate.Other reported scoring systems did not show statistically significant differences: Hospital for Special Surgery (HSS) score (seven studies in 1021 knees) with an MD of -1.36 (95% CI -4.18 to 1.46, P value 0.35); Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) total score (two studies, 167 knees) with an MD of -4.46 (95% CI -16.26 to 7.34, P value 0.46); and Oxford total (five studies, 647 knees with an MD of -0.25 (95% CI -1.41 to 0.91, P value 0.67).

Health-related quality of lifeThree studies with 498 knees reported on health-related quality of life, and no statistically significant differences were noted between the mobile bearing and fixed bearing groups. The Short Form (SF)-12 Physical Component Summary had an MD of -1.96 (95% CI -4.55 to 0.63, P value 0.14).

Revision surgeryTwenty seven revisions (1.3%) were performed in 17 studies with 2065 knees. In all, 13 knees were revised in the fixed bearing group and 14 knees in the mobile bearing group. No statistically significant differences were found (risk difference 0.00, 95% CI -0.01 to 0.01, P value 0.58).

MortalityIn seven out of 19 studies, 13 participants died. Two of these participants had undergone bilateral surgery, and for seven participants, it was unclear which prosthesis they had received; therefore they were excluded from the analyses. Thus our analysis included four out of 191 participants (2.1%) who had died: one in the fixed bearing group and three in the mobile bearing group. No statistically significant differences were found. The risk difference was -0.02 (95% CI -0.06 to 0.03, P value 0.49) and results were homogeneous.

Reoperation ratesThirty reoperations were performed in 17 studies with 2065 knees: 18 knees in the fixed bearing group (of the 1031 knees) and 12 knees in the mobile group (of the 1034 knees). No statistically significant differences were found. The risk difference was -0.01 (95% CI -0.01 to 0.01, P value 0.99).

Clinical comments

Note

Date of latest search: 2014-02-27

    References

    • Hofstede SN, Nouta KA, Jacobs W et al. Mobile bearing vs fixed bearing prostheses for posterior cruciate retaining total knee arthroplasty for postoperative functional status in patients with osteoarthritis and rheumatoid arthritis. Cochrane Database Syst Rev 2015;(2):CD003130. [PubMed]

Primary/Secondary Keywords