gms | German Medical Science

Objectives: Tears of the gluteus minimus or medius as an underlying source of greater trochanteric pain syndrome are often missed and the resultant ineffective or false treatment leads to poor outcome. A recently described mini-open surgical approach consists of a knotless and laminar double-row repair (HipBridge (HB) technique) to anatomically refixate the gluteal tendons with large-area contact. As biomechanical data is still lacking to date, the aim of this study was to prove superiority of the HB repair over standard Mason-Allen (MA) technique.

Methods: The gluteus medius and minimus was released and reattached to its footprint in 12 fresh-frozen human cadaveric specimens (5 male, 7 female; mean age 63 ± 7 years; mean BMI 27 ± 5) with two techniques: First, a transosseous MA repair (n = 6), and second a knotless double-row HB repair (n = 6) using proximally two anchors loaded with nonresorbable suture tape which was double-V-shaped and then distally fixated with two additional anchors.

The potted femur was attached to the baseplate of a tensile testing machine (Instron) and the gluteal muscles were clamped using a custom cryo-jaw. The constructs underwent a test protocol including a preload of 10 N and cyclic loading from 10 to 125 N for 150 cycles at 2.5 Hz prior to a pull to failure. Each test was additionally tracked using an optical measurement system (GOM) to evaluate the elongation of the repair technique. Statistical analysis included a one-tailed t-test and significance level was set at p < 0.05.

Results and conclusion: Two HB constructs failed immediately due to tissue failure and were therefore excluded from further evaluation. The final plastic elongation obtained from optical tracking measurements was 4.41 ± 0.48 mm for MA and 3.16 ± 1.49 mm for HB repair (p = 0.096).

Figure 1 [Fig. 1]

Optical measurement recordings including time over displacement data of HipBridge repair technique during cyclic loading. None of the HB but one of the MA constructs exceeded the 5 mm critical threshold of clinical failure during cyclic loading. During pull to failure, a construct stiffness of 59.7 ± 13.0 N/mm for MA and 74.2 ± 10.0 N/mm for HB technique was observed (p = 0.045). The ultimate load was significantly higher for HB (380 ± 129 N compared to 210 ± 62 N for MA, p = 0.036). HB constructs failed due to tendon failure, whereas the MA constructs showed three failure modes: tendon failure, bone cutting and muscle rupture (Table 1 [Tab. 1]).

Testing results (mean ± SD) and p values of one-tailed t-test for techniques tested. The HB repair provides biomechanical stability with less elongation, albeit differences were not statistically significant, and higher ultimate load compared to standard MA technique. Additionally, the knotless double-row HB repair restores an anatomic footprint by a large-area contact and therefore allows for a stable and reproducible refixation of gluteal tendons.