ISAKOS: 2019 Congress in Cancun, Mexico

2019 ISAKOS Biennial Congress ePoster #902


A Feasibility Study Considering the Use of a New Medical Stretching Device (STAK Tool) in 19 Patients with Knee Arthrofibrosis, Following Total Knee Replacement, Being Considered for Manipulation Under Anaesthetic

Sara Aspinall, BSc, MSc(R), Loughborough UNITED KINGDOM
Daniel Fong, PhD, Loughborough UNITED KINGDOM
Steven Godsiff, MD, Norwich UNITED KINGDOM

University Hospitals of Leicester NHS Trust, Loughborough University, Leicester, UNITED KINGDOM

FDA Status Not Applicable


This study evaluates the STAK Tool a new medical stretching device to be used at home in treating arthrofibrosis following total knee replacement. Patients achieved a significant increase in both knee flexion (mean 30°, range 12°-50°), WOMAC (mean change 20.8, p<0.001) and Oxford Knee Scores (mean change 7.7, p<0.001).The STAK may offer a new, cost effective treatment for arthrofibrosis.



Whilst medical stretching devices for home use in the treatment of arthrofibrosis are used in the USA none are currently available in the NHS or in Europe.
Around 109,000 total knee replacement’s (TKR) are performed each year in the UK and 600,000 in the USA. Due to obesity and longevity this is expected to increase six-fold by 2030 (Culliford 2015, Fayaz 2011). Approximately 10% of cases develop arthrofibrosis, which has debilitating effects on patients' basic everyday activities. This study evaluates a new home medical stretching device called the STAK Tool in treating knee arthrofibrosis.


19 patients following TKR (mean 10.5 weeks) who failed routine postoperative rehabilitation, having less than 80° flexion (mean 64.57°, range 44°-75°) were recruited. Two patients had received manipulations under anaesthetic (MUA) which had not been successful. Patients received 8 weeks standard treatment plus independent stretching using a STAK Tool at home for up to 60 mins a day. WOMAC and Oxford knee scores were collected before and after treatment.


The patient’s mean increase in knee flexion range of movement (ROM) was 30°(range 12°-50°). This was a statistically significant increase (p<0.001). The patients also demonstrated significant improvements in WOMAC (mean change 20.8, p<0.001) and Oxford Knee Scores (mean change 7.7, p<0.001). No patients suffered any complications as a result of using the STAK. Two patients withdrew from the study at an early stage. All patients found the STAK Tool ‘perfectly acceptable’ on a 7 point likert scale and said they would recommend it to a friend. Patients reported improvement in function and a feeling of being in control of their rehabilitation.


Improvements in ROM compare favourably with Bonutti´s (2010) research using the JAS Device in USA where patients achieved a mean increase in ROM of 25° (range 8°-82°). It compares favourably with patients treated with MUA. Published results following MUA demonstrate mean increases in ROM of 26.5 (range 0°-80°) (Ipach 2011). However MUA is not without risk and can result in complications and limited lasting gains in ROM (Yercan 2006). This study indicates the STAK is a useful tool for increasing ROM.


We are encouraged by this study's early results and will report later the longer term follow up to see if ROM increase is maintained. Comparison of a control group receiving standard physiotherapy alone is currently in progress.