Overstretching Expectations May Endanger the Success of the “Millennium Surgery”

Abstract

Total hip arthroplasty (THA) is an extremely successful treatment strategy. Patient expectations, however, have increased; if not properly guided by surgeons, at present, patients expect next to pain-free restoration of the joint and a fast return to work and sports. While the revision rates after THA also increased in younger patients, knowledge on musculoskeletal loads still remains sparse, and the current recommendations on postoperative rehabilitation are based on expert opinions only. The aim of this study was to unravel biomechanical contact conditions in “working age” (<60 years, 53.5 ± 3.0 years) and “retirement age” (>60 years, 67.7 ± 8.6 years) patients during activities recommended post-THA. We hypothesized that working age patients would show substantially increased hip contact loads compared to older patients. The in vivo joint contact force (Fres) and torsion torque (Mtors), reflecting the main contact load situation, experienced during activities of daily living and sports activities were measured in a unique group of 16 patients with instrumented THA. We summarized patient activities and sports recommendations after THA mentioned within the literature using PubMed (without claim of completeness). The measurements showed that younger working age patients experienced significant (p = 0.050) increased Mtors (21.52 ± 9.11 Nm) than older retirement age patients (13.99 ± 7.89 Nm) by walking. Bowling, as a recommended low-impact sport, was associated with Fres of up to 5436 N and Mtors of up to 108 Nm in the working age group, which were higher than the Fres (5276 N) and Mtors (71 Nm) during high-impact soccer. Based on our results, age was proven to be a discriminator in joint loading, with working age patients presenting with increased loads compared to retirement age patients, already during daily activities. The current patient recommendations have led to further increased joint loadings. If THA cannot be delayed in a patient, we propose counselling patients on a carefully considered return to sports, focusing on low-impact activities, as indicated hereby. The findings from this work illustrate the need to provide critical feedback to patient expectations when returning to work and sports activities. Patients returning to more intensive sports activities should be carefully monitored and advised to avoid as much overloading as possible.

Activity Following Total Hip Arthroplasty: Which Patients Are Active, and Is Being Active Safe?

“…Aseptic loosening occurred in three low-activity patients and only one high-activity patient. The risk of aseptic loosening due to implant wear is frequently cited as an argument against high activity [5,6,19,37]. However, the current findings suggest that, despite the biomechanical proof of increased wear due to increased forces, actual clinical findings may not justify general advice against high physical activity [17,18].…”

“…They also found that working-age patients showed higher contact loads compared to retirement-age patients during daily activities. Based on these results, it has been suggested that recommendations of sporting activities should be mainly focused on low-impact activities, especially for younger patients [37]. Higher revision rates for younger patients and males compared to females have been reported previously.…”

“…However, skiing with short turns on a steep sloped showed far higher contact forces [36]. Bowling was regularly considered a recommended low-impact sport, yet when evaluating joint contact force and torsion torque in working-age THA patients, Bender et al found higher forces on the hip during bowling than during high-impact soccer [37,38]. They also found that working-age patients showed higher contact loads compared to retirement-age patients during daily activities.…”

Loading of the Hip and Knee During Swimming

“…Following total joint arthroplasty, the torsional moment around the femoral shaft axis or the tibial axis is a crucial parameter greatly influencing micromotion at the implant-bone interface 19,39 . For patients who underwent THA, the maximal torsional moment around the femoral shaft axis at all velocities in breaststroke swimming (median, 0.87% BWm) in this study was lower than the values reported in weight-controlled walking (1.53% BWm) 9 and common physiotherapies (2.18% BWm) 10 .…”

“…The contact force direction was determined as the angle α between F Res and the vertical axis in the frontal plane and the angle β between F Res and the vertical axis in the sagittal plane. Additionally, the torsional moment (M Tors ) around the femoral shaft axis or the tibial axis, the bending moment (M Bend ) at the middle of the femoral neck, and the torsional moment (M Tne ) around the femoral neck axis were calculated by previously described methods 19 . The mediolateral force distribution in the knee was calculated as the medial force ratio (MFR) between the medial axial force (F Med ) and the sum of F Med and the lateral axial force (F Lat ) 20,21 (Fig.…”