Clinically Important Reductions in Physical Function and Quality of Life in Adults with Tumor Prostheses in the Hip and Knee: A Cross-sectional Study
Authors: Fernandes Linda , Holm Christina Enciso , Villadsen Allan , Sørensen Michala Skovlund , Zebis Mette Kreutzfeldt , Petersen Michael Mørk 
Published: May 2021

Abstract

Background
Patients with a bone sarcoma who undergo limb-sparing surgery and reconstruction with a tumor prosthesis in the lower extremity have been shown to have reduced self-reported physical function and quality of life (QoL). To provide patients facing these operations with better expectations of future physical function and to better evaluate and improve upon postoperative interventions, data from objectively measured physical function have been suggested.

Questions/purposes
We sought to explore different aspects of physical function, using the International Classification of Functioning, Disability, and Health (ICF) as a framework, by asking: (1) What are the differences between patients 2 to 12 years after a bone resection and reconstruction surgery of the hip and knee following resection of a bone sarcoma or giant cell tumor of bone and age-matched controls without walking limitations in ICF body functions (ROM, muscle strength, pain), ICF activity and participation (walking, getting up from a chair, daily tasks), and QoL? (2) Within the patient group, do ICF body functions and ICF activity and participation outcome scores correlate with QoL?

Methods
Between 2006 and 2016, we treated 72 patients for bone sarcoma or giant cell tumor of bone resulting in bone resection and reconstruction with a tumor prosthesis of the hip or knee. At the timepoint for inclusion, 47 patients were alive. Of those, 6% (3 of 47) had undergone amputation in the lower limb and were excluded. A further 32% (14 of 44) were excluded because of being younger than 18 years of age, pregnant, having long transportation, palliative care, or declining participation, leaving 68% (30 of 44) for analysis. Thus, 30 patients and 30 controls with a mean age of 51 ± 18 years and 52 ± 17 years, respectively, were included in this cross-sectional study. Included patients had been treated with either a proximal femoral (40% [12 of 30]), distal femoral (47% [14 of 30]), or proximal tibia (13% [4 of 30]) reconstruction. The patients were assessed 2 to 12 years (mean 7 ± 3 years) after the resection-reconstruction. The controls were matched on gender and age (± 4 years) and included if they considered their walking capacity to be normal and had no pain in the lower extremity. Included outcome measures were: passive ROM of hip flexion, extension, and abduction and knee flexion and extension; isometric muscle strength of knee flexion, knee extension and hip abduction using a hand-held dynamometer; pain intensity (numeric rating scale; NRS) and distribution (pain drawing); the 6-minute walk test (6MWT); the 30-second chair-stand test (CST); the Toronto Extremity Salvage Score (TESS), and the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30). The TESS and the EORTC QLQ-C30 were normalized to 0 to 100 points. Higher scoring represents better status for TESS and EORTC global health and physical functioning scales. Minimum clinically important difference for muscle strength is 20% to 25%, NRS 2 points, 6MWT 14 to 31 meters, CST 2 repetitions, TESS 12 to 15 points, and EORTC QLQ-C30 5 to 20 points.

Results
Compared with controls, the patients had less knee extension and hip abduction strength in both the surgical and nonsurgical limbs and regardless of reconstruction site. Mean knee extension strength in patients versus controls were: surgical limb 0.9 ± 0.5 Nm/kg versus 2.1 ± 0.6 Nm/kg (mean difference -1.3 Nm/kg [95% CI -1.5 to -1.0]; p < 0.001) and nonsurgical limb 1.7 ± 0.6 Nm/kg versus 2.2 ± 0.6 Nm/kg (mean difference -0.5 Nm/kg [95% CI -0.8 to -0.2]; p = 0.003). Mean hip abduction strength in patients versus controls were: surgical limb 1.1 ± 0.4 Nm/kg versus 1.9 ± 0.5 Nm/kg (mean difference -0.7 Nm/kg [95% CI -1.0 to -0.5]; p < 0.001) and nonsurgical limb 1.5 ± 0.4 Nm/kg versus 1.9 ± 0.5 Nm/kg (-0.4 Nm/kg [95% CI -0.6 to -0.2]; p = 0.001). Mean hip flexion ROM in patients with proximal femoral reconstructions was 113° ± 18° compared with controls 130° ± 11° (mean difference -17°; p = 0.006). Mean knee flexion ROM in patients with distal femoral reconstructions was 113° ± 29° compared with patients in the control group 146° ± 9° (mean difference -34°; p = 0.002). Eighty-seven percent (26 of 30) of the patients reported pain, predominantly in the knee, anterior thigh, and gluteal area. The patients showed poorer walking and chair-stand capacity and had lower TESS scores than patients in the control group. Mean 6MWT was 499 ± 100 meters versus 607 ± 68 meters (mean difference -108 meters; p < 0.001), mean CST was 12 ± 5 repetitions versus 18 ± 5 repetitions (mean difference -7 repetitions; p < 0.001), and median (interquartile range) TESS score was 78 (21) points versus 100 (10) points (p < 0.001) in patients and controls, respectively. Higher pain scores correlated to lower physical functioning of the EORTC QLQ-C30 (Rho -0.40 to -0.54; all p values < 0.05). Less muscle strength in knee extension, knee flexion, and hip abduction correlated to lower physical functioning of the EORTC QLQ-C30 (Rho 0.40 to 0.51; all p values < 0.05).

Conclusion
This patient group demonstrated clinically important muscle weaknesses not only in resected muscles but also in the contralateral limb. Many patients reported pain, and they showed reductions in walking and chair-stand capacity comparable to elderly people. The results are relevant for information before surgery, and assessments of objective physical function are advisable in postoperative monitoring. Prospective studies evaluating the course of physical function and which include assessments of objectively measured physical function are warranted. Studies following this patient group with repetitive measures over about 5 years could provide information about the course of physical function, enable comparisons with population norms, and lead to better-designed, targeted, and timely postoperative interventions.

Level of Evidence
Level III, therapeutic study.