In vivo loading on the hip joint in patients with total hip replacement performing gymnastics and aerobics exercises

Abstract

A further increase in the number of total hip arthroplasty (THA) is predicted, in particular the number of young THA patients has raised and with it their demands. There is no standardized evidence-based rehabilitation program and no reliable guidelines for sports activities after THA. Stretching and strengthening gymnastics are routinely performed in rehabilitation and aerobics as a sport after THA. The aim of the investigation was to determine the in vivo force and moments acting on the hip prosthesis during gymnastics and aerobic exercises to provide a source for evidence-based recommendations. Hip joint loads were measured in six patients with instrumented hip implants. The resulting force F_Res, bending moment M_Bend at the neck and torsional moment M_Tors at the stem were examined during seven strengthening (with two different resistance bands) and four stretching gymnastic exercises and seven aerobic exercises with and without an aerobic step board compared to the loads during the reference activity walking. The stretching and strengthening gymnastics exercises and the aerobic exercises with and without a board demonstrated in their median peak force and moments mostly lower or similar values compared to walking. Significantly increased loads were recorded for the flexor stretching exercise in monopod stand (F_res and M_Bend), the strengthening abduction exercise on the chair (M_Tors) and the strengthening flexion exercise with the stronger resistance band (M_Tors). We also found a significant increase in median peak values in aerobic exercises with a board for the "Basic Step" (ipsilateral started F_res and M_Tors; contralateral started M_Tors), "Kickstep ipsilateral started" (F_res and M_Tors) and "Over the Top contralateral started" (F_res). The in vivo loads in THA patients during frequently performed stretching, strengthening and aerobic exercises were demonstrated for the first time. It was proved that stretching gymnastic exercises are safe in terms of resulting force, bending and torque moments for THA patients, although an external assistance for stabilization may be considered. Strengthening gymnastics exercises are reliable in terms of F_res, M_Bend and M_Tors, but, based on our data, we recommend to adhere to the communicated specific postoperative restrictions and select the resistance bands with lower tension. Aerobic exercises without an aerobic board can be considered as reliable activity in terms of force and moments for THA patients. Aerobic exercises with a board are not recommended for the early postoperative period and in our opinion need to be adapted to the individual muscular and coordinative resources.

Figure 1

In vivo determined joint loads; resultant joint contact force (F_res) in the hip joint, the bending moment at the femur neck (M_Bend) and the torsion torque around the femur stem (M_Tors).

Figure 2

Examples of the averaged pattern of the resultant joint contact force F_res (black), the bending moment at the femur neck M_bend (blue) and torsion torque around the femur axis M_tors (green); (a) during walking as reference activity #1; (b) hip adduction on chair #8, (c) hip flexion step ipsilateral #24, (d) hip flexion-monopod position contralateral #23, (e) V-step ipsilateral #28, and (f) basic step ipsilateral #31.

Figure 3

Comparison of F_res, M_Tors and M_Bend acting on the hip joint during strengthening gymnastic exercises (#2)–(#17), stretching gymnastics exercises (#18)–(#25) and aerobic exercises (#26)–(#36) compared to reference exercise walking (#1) (grey area). The median, minimum and maximum values are presented. Grey area indicates reference level of ground walking (minimum to maximum). (#1) reference level walking, (#2) Hip Abduction Chair-ipsi Thera; (#3) Hip Abduction Chair-contra Thera, (#4) Hip Abduction Ground-ipsi Thera, (#5) Hip Abduction Ground-contra Thera, (#6) Hip Abduction Ground-ipsi Deuser, (#7) Hip Abduction Ground-contra Deuser, (#8) Hip Adduction Chair, (#9) Hip Adduction Ground-ipsi Thera, (#10) Hip Flexion Standing-ipsi Thera, (#11)Hip Flexion Standing-contra Thera, (#12) Hip Flexion Standing-ipsi Deuser, (#13) Hip Flexion Standing-contra Deuser, (#14) Hip External Rotation Ground-Thera, (#15) Hip External Rotation Ground-Deuser, (#16) Hip Internal Rotation Ground-ipsi Thera, (#17) Hip Internal Rotation Ground-ipsi Deuser, (#18) Hip Abductors-ipsi, (19) Hip Abductors-contra, (#20) Hip Adductors-ipsi, (#21)Hip Adductors-contra, (#22) Hip Flexion-monopod –ipsi, (#23) Hip Flexion-monopod-contra, (#24) Hip Flexion-step position-ipsi, (#25) Hip Flexion-step position-contra, (#26) Marching, (#27) Tap, (#28) V-Step-ipsi, (#29) V-Step-contra, (#30) Hamstring Curl, (#31) Basic Step-ipsi, (#32) Basic Step-contra, (#33) Kick Step-ipsi, (#34) Kick Step-contra, (#35) Over the Top-ipsi, (#36) Over the Top-contra.