Biomechanical strength testing of press-fit techniques has been performed by several investigators. Most of the work has been done on the femoral-sided fixation. Rupp et al. compared femoral press-fit fixation with biodegradable and titanium interference screw in porcine lower limbs. He found significantly higher ultimate loads in screw compared to press-fit fixation [21]. Musahl et al. also compared press-fit femoral fixation with interference screw fixation in hind limbs of Saanen breed goats. In his analysis, no statistically significant difference was found between two groups based the cyclic creep tests and uniaxial tensile loading. But he also noted lower ultimate load for press-fit fixation vs screw fixation. Data from their study supported early functional post-op rehab regimens but suggested tailoring rehab protocols to allow bone healing [22]. Seil et al. used a cyclic loading protocol in porcine lower limbs. The press-fit group failed in five specimens [23]. The authors concluded that press-fit fixation is not secure enough for accelerated rehabilitation protocol.

On the contrary, Lee et al. compared femoral press-fit fixation performed with a 1.4 mm oversized bone plug to interference screw and reported no difference in stiffness and linear load or failure mode [24]. Kuhne et al. reported average primary stability of 570 N (±100 N) for the bone-blocking BTB technique and 402 N (±79 N) for the interference screw fixation [25]. Mayr et al. reported the same fixation properties for press-fit dowel (slashed circle 7 mm) with 100 N axial load and interference screw [26].

Authors have also investigated effect of variables like loading direction, the length of bone plug, and method of preparation for femoral tunnel. Schmidt Wiethoff measured a failure rate of 333 N for 25 mm length and recommended a length of the bone cylinder by 20–30 mm [27]. Pavlik et al. measured a ultimate tensile strength of 534 N at 45° [28] and Seil et al. at an angle of 80° between load axis and tunnel axis with 708 N (± 211) [19]. Dargel et al. found a higher fixation quality for a dilated tunnel up to 1 mm, thereby compacting cancellous bone [29]. He also reported comparable failure loads for quadriceps tendon patellar bone and patellar BTB in a cadaveric study. Kilner et al. [30] compared knot/press-fit technique for hamstring with commonly used endobutton technique and found no difference in anterior tibial translation in response to anterior tibial load. Stiffness of the knot/press-fit complex was found to be 37.8 N/mm, and the load at failure was 540 N, which was comparable with other devices. Similar findings were noted for knot/press-fit hamstring by Lin et al. [16].

Press-fit tibial fixation has been compared with other commonly used methods. Boszotta et al. showed a significantly higher primary stability of 758 N (range, 513–993 N) for press-fit fixation in comparison to interference screw 572 N (range, 473–680 N), staple 608.4 N (range, 511–727 N), and suture over a bone bridge 304.5 N (range, 120–327 N) [31]. Jagodzinski et al. found the highest maximum load to failure for the extra tape fixed press-fit fixation at 970 ± 83 N, followed by the interference screw fixation with 544 ± 109 N, and the suture press-fit fixation with 402 ± 78 N [32]. In a porcine femur model, Ettinger et al. found that a tibial press-fit technique that uses an additional bone block has better maximum load to failure compared to an interference screw fixation. But for the bone block fixation only technique (author’s technique), it was found to be 290 ± 74 N only [33]. The same group investigated the tibial PCL fixation. The maximum load to failure was 518 ± 157 N for the hamstring with a knot, 558 ± 119 N for the interference screw, and 620 ± 102 N (541–699 N) for the quadriceps tendon bone block [34].