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 (F res) and torsion torque (M tors), 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 M tors (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 F res of up to 5436 N and M tors of up to 108 Nm in the working age group, which were higher than the F res (5276 N) and M tors (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.
Highlights
The “operation of the century”—total hip arthroplasty (THA) (Learmonth et al, 2007)—has been demonstrated to be extremely effective for decades (Jenkins et al, 2013)
The t-test indicated a significant difference in BW/BMI between both groups [BW: t(13.9) = 2.69, p = 0.018, 95% confidence interval (CI) = 3.31–29.20; BMI: t(13.1) = 1.98, p = .069, 95% CI = −.35 to 8.16)], with a strong Cohen’s effect size (BW: ds = 1.32; BMI: ds = .93)
To obtain an impression of the magnitude of Fres and Mtors, we present in Figure 4 the results of our first in vivo data collected during activities that were ranked according to the above classifications into low, intermediate, and high-impact sports levels
Summary
The “operation of the century”—total hip arthroplasty (THA) (Learmonth et al, 2007)—has been demonstrated to be extremely effective for decades (Jenkins et al, 2013). Despite the overall increase in numbers and younger patients, the lifetime of a functional hip joint arthroplasty has remained at 15–20 years over the last decades (Junnila et al, 2016; Swarup et al, 2018). THA was implemented to reduce acute pain and allow painless mobility in daily life in older patients with degenerated joints (Wright et al, 1994). For these patients, longlasting success rates have been realized. The present expectations include returning to full functional and recreational activities (Healy et al, 2008; Mancuso et al, 2009) in daily life and to work and sport (Hoorntje et al, 2018), or eventually to start with new activities (Schmidutz et al, 2012)
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