To our knowledge, this is the first study applying the principles of neuromuscular training, successfully used in younger and middle aged individuals with knee injury, to older people with severe hip or knee OA. We found that the individualized, goal-based neuromuscular training program, the NEMEX-TJR, was feasible in these patients in terms of safe self-reported pain after training, decreased or unchanged pain during the training period, few joint-specific adverse events, and achieved progression of training level during the training period.
General exercise, such as aerobic exercise and strength training, is generally recommended for improving overall health. General exercise is also recommended for people with OA, since such interventions show positive effects in terms of reduced pain and improved function [5
]. The muscles contribute considerably to stabilizing the joints [24
], and, therefore, training targeting the more specific needs related to the joint injury/disease has an important role in the treatment. It was suggested that joint-specific strengthening exercises are needed in the management of OA [4
], and training programs have traditionally focused largely on strengthening lower extremity muscles [7
]. However, neuromuscular training is successfully used in the prevention and treatment of knee injuries [10
], i.e., in people at high risk of knee OA [9
]. Such training may be important also for people with OA [7
Neuromuscular training aims to improve sensorimotor control and obtain compensatory functional stability. Knee injury (ACL injury, meniscal injury, cartilage damage) leads to functional instability, i.e., a sudden loss of control of the injured joint in a weight-bearing position, and defective neuromuscular function (e.g., reduced strength and functional performance, differences in movement and muscle activation patterns, proprioceptive deficiency, and impaired postural control) [12
]. These limitations are also reported by and observed in people with OA [7
]. In our opinion, this warrants the use of neuromuscular training in people with OA.
Although most studies deal with general exercise in hip or knee OA, there are some studies on training in people with OA where functional exercises are used [27
]. However, key components of neuromuscular training were lacking in these studies; principles of training, and level and progression of training, allowing an individualized approach, was described only in a case-report [27
], and the quality of performance of exercises was not mentioned in any of these studies [27
In accordance with that observed in people with knee injury, associated symptoms and functional limitations are heterogeneous in people with OA. Therefore, factors such as age, gender, previous and desired activity level, type of and severity of injury/disease, symptoms, and functional limitations are taken into account for each individual during neuromuscular training. An individualized approach to exercise based on various factors related to the joint and the individual is in line with that recommended for people with OA [4
Both patients with knee OA and those with hip OA reported safe pain (median 2 cm) after training, a clear majority of the patients had acceptable pain after the training sessions, and there was no difference in self-reported pain after vs. before training sessions. We included a pain monitoring system, used previously in people with patellofemoral pain syndrome [20
], to help the patients adjust training with regard to their perceived pain. The patients were told that pain was allowed up to 5 on a 0 ("no pain") to 10 ("pain as bad as it could be") scale during and after a training session, and the patients graded their pain on this 0 to 10 scale after each training session. They were also told that pain should subside to "pain as usual" the day after training, and if pain did not subside, progression of training was slowed down. The patients in our study did not report pain 24 hours after training, but we found that self-reported pain was decreased or unchanged over time, indicating that pain did subside. However, to ensure this, self-reported pain immediately after and 24 hours after training can be included in future studies. The effects of the NEMEX-TJR training program on pain and symptoms remain to be studied.
There were only few (n = 17, 22%) adverse events in terms of self-reported pain > 5 on the 0 to 10 scale. The highest number of patients (n = 6) with self-reported pain > 5 was observed after one training session only, and there were few patients (n = 4) with self-reported pain > 5 after more than 4 training sessions. Only two patients ceased training, one patient for unknown reasons and the other patient for reasons not related to the joint disease or training.
The NEMEX-TJR training program is divided into three levels of difficulty. All three training levels were used, and the training level was progressed over time. Because the training is individualized and goal-based, all patients did not progress to the third training level. The physical therapist supervising the training was experienced and specializing in training of musculoskeletal disorders, and we consider this a requirement in order to modify the exercises for each individual. Training took place in groups, to utilize the positive effects of group training in terms of more effective learning compared with individual practice sessions, and reduced costs [30
]. As the exercises require little equipment, the training program can easily be employed in clinical settings and at home.
We found that the NEMEX-TJR training program was feasible in patients with severe hip or knee OA. Future studies should focus on the effects of the NEMEX-TJR on physical function and self-reported outcomes, dose-response, and comparison of this training program with other treatment. Another subject for further study may be training with the aim of postponing surgery. Such an approach would be of specific value for younger patients.