Table 1.

Study type, sample size and sample characteristics

Study type	Number	Sample size (N)	N Male	N Female	Age (SD)
Measurement	17	1236	458	763	54.9 (6.4)
Surgery	30	1512	648	857	45.1 (15.7)
Orthoses	19	1101	493	521	43.0 (15)
Other intervention	4	170	55	115	47.6 (6.1)
Observational	8	695	260	432	52.2 (27.9)
Total	78	4714	1914* (41%)	2688* (57%)	48.58 (4.9)

*Gender not reported in 3 studies: Slattery, M [82] (2001), Clark, H [85] (2010) and Kulig, K [88] (2009).