Evaluation of a new home use medical stretching device, the STAK tool to treat arthrofibrosis of the knee

This thesis considers the worldwide problem of arthrofibrosis following total knee replacement surgery and evaluates the role of a new medical stretching device, the STAK tool in its treatment of arthrofibrosis. The aims of the thesis included carrying out a systematic review to investigate the effectiveness of medical stretching devices in increasing knee range of movement (ROM) in arthrofibrosis patients followed by a clinical trial to evaluate a new device (The STAK) to treat arthrofibrosis and poor ROM following total knee replacement (TKR) and major knee surgery. Qualitative research was used to explore patients’ experience of daily living with arthrofibrosis focusing on their perceptions of outpatient standard physiotherapy treatment compared to home use of the high intensity medical stretching device The STAK and feasibility of the study procedures for a future trial.

Methods

Study 1 comprised a systematic review of 12 articles (558 participants) from peer reviewed journals investigating the effectiveness of 3 different types of medical stretching devices: continuous passive motion (CPM), load control and load displacement devices. Study 2 (the clinical trial) involved the recruitment of 35 patients post-major knee surgery with arthrofibrosis and mean ROM of 68°. Both the STAK intervention (18 patients) and control group received standard physiotherapy for 8 weeks, with the intervention group additionally using the STAK tool at home. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Oxford Knee Scores (OKS) were collected at all timepoints. An acceptability and home exercise questionnaire capturing adherence was recorded after each of the interventions. In study 3 semi-structured interviews were conducted with 18 arthrofibrosis patients (intervention group). Interviews were recorded and transcribed and reflexive thematic analysis conducted. Findings were integrated into the quantitative results to add depth and understanding.

Results

Study 1 demonstrated a statistically significant increase in ROM as demonstrated in CPM, load-control and displacement-control studies (p<0.001). The results show that the stretch doses applied using the CPM, load-control devices were performed over a considerably longer treatment time and involved significantly more additional physiotherapy compared to the displacement-control and patient actuated serial stretching devices. The wide range in ROM gains of patients in the same studies suggested the need to use qualitative methods to explore factors underlying this. In study 2 compared to the control group, the STAK intervention group made significant gains in mean ROM (30° versus 8°, p<0.001), WOMAC (23 points versus 3, p<0.001), and OKS (9 points versus 4, p <0.05). The improvements in the STAK group were maintained at long-term follow-up (10.5 months). No patients suffered any complications relating to the STAK, and 96% of patients found the STAK tool ‘perfectly acceptable’.

In study 3 patient interviews revealed how severe pain and stiffness imposed by major physical limitations were compounded further by accompanying social and psychological problems. Integration of the qualitative research findings corroborated and augmented the quantitative results. Major themes identified stressed the importance of the STAK high intensity stretching device essential to regain ROM, the necessity for effective pain management and the benefits to be gained from a supportive therapist patient relationship.

Implications for clinical practice

It is recommended that home use of displacement control medical stretching devices is incorporated into standard physiotherapy treatment following total knee replacement. Stretching the knee to maximum intensity is demanding, painful and necessary to enable patients to regain ROM. It is recommended that physiotherapists discuss pain medication with their patients to ensure that they can fully engage in their treatment. The importance of a positive and supportive therapist patient relationship is emphasised to optimise treatment outcomes.