Table 2 Qualitative Review of Study Results

Clifton et al. 2014

15 (67%) TMC arthroplasty patients

Tissue sampling

Immunostaining for RXFP1 in dorsoradial ligaments and synovium

RXFP1 will be present in tissues stabilizing the TMC joint; therefore, relaxin could impact joint stability

Stratifying data by disease severity (Eaton–Littler score, timing to trapeziectomy) demonstrated a rapid pace of TMC degradation in women. Women were significantly younger at time of trapeziectomy, with a strong positive correlation of Eaton score and RXFP-1 concentration

Em et al. 2015

88 (100%) women; 48 with BJHS and 40 controls

Assessment for hypermobility, SRC

Average SRC in women with BJHS vs. controls

Elevated relaxin may play a role in certain physiologic manifestations of BJHS

Serum relaxin levels of the BJHS group were non-significantly higher than controls (47.1 ± 20.3 pg/mL, 34.4 ± 22.1 pg/mL; p = 0.28). BJHS subjects had higher incidence of musculoskeletal pathologies, significantly (p < 0.05) arthralgia (33.3% vs. 25%), myalgia (55.6% vs. 27.5%), pes planus (57.8% vs. 30%), and hyperkyphosis (62.2% vs. 22.5%). The median relaxin levels were significantly greater in BJHS vs. control subjects with pes planus (33.3 vs. 16.4, p = 0.05) and/or hyperkyphosis (33.3 vs. 12.0, p < 0.05)

Lubahn et al. 2006

8 (100%) premenopausal women; TMC arthroplasty, FCR repair

Tissue Sampling

Presence of relaxin receptors in volar oblique ligament

Female TMC OA prevalence may result from hormone-induced laxity of the volar oblique ligament. Relaxin is likely the hormone, it signals collagenases

Relaxin specifically bound all VOLs, with binding of cervical tissue > VOL > meniscal tissue. It was presumed that specific VOL binding of relaxin indicated cellular and/or extracellular matrix receptors. The lack of men presenting for treatment/study was noted

Pokorny et al. 2000

55 (100%) women aged 20–25; 3 months with 30 on low-dose OCPs (test), 25 not

AP tibial translation, 5th DIP extension, 2nd PIP abduction, adduction

Knee and hand laxity in OCP users vs. non-users

The average joint laxity of women on OCPs will be higher than women not on OCPs, due to the endogenous estrogen and progesterone

Joint laxity had no significant difference between groups, including when stratified by cycle day groups. The control group had non-significant greater knee laxity during CD23+, and 2nd PIP laxity during CD12–22

Wolf et al. 2012

49 (61%) patients; TMC arthroplasty, trapeziectomy, ligament repair

Preoperative Beighton score and SRC, tissue sampling

SRC, RXFP1 amount on anterior oblique ligament, relationship between MMP-1/MMP-13 and RXFP1 location

Relaxin is potentially involved in TMC joint laxity and eventual OA, via laxity of the anterior oblique ligament

Higher serum relaxin correlates with more thumb-area relaxin receptors and MMP-1 expression. Average mixed-sex expression levels were 3.73 pg/mL (0–9.45 pg/mL) for SRC, 5.23*10⁶ag for RXFP1 receptor, 0.022ag for MMP-1, and 0.318ag for MMP-3. Serum relaxin had significant relationships vs. log RXFP1 (p = 0.02); and vs. MMP-1 (p = 0.05). RXFP1, MMP-1, and MMP-3 were identified on the anterior oblique ligament

Wolf, J.M, Cameron, K.L. et al. 2013

289 (53%) healthy volunteers

Screening for hypermobility (Beighton), TMC stress X-rays, SRC testing

SRC effect on general laxity, TMC joint laxity

High serum relaxin levels will correlate with laxity on TMC stress X-rays; it will also be associated with generalized joint laxity

42% of subjects had detectable SRC; 63% of women and 37% of men. SRC was 2.5 × greater in women, significant in 40–59yo’s. The all-ages female vs. male average SRC was 2.6 + 7.0 vs. 0.99 + 2.4, p < 0.05; with less significance when limited to detectable values. Women, particularly younger age groups, were more lax. SRC-detectable subjects had greater TM laxity, but only when controlling for age. Greater TM laxity was related to SRC, but so was younger age