PAIN, TRUNK MUSCLE STRENGTH, SPINE MOBILITY AND DISABILITY FOLLOWING LUMBAR DISC SURGERY Arja Ha ¨kkinen, 1 Jari Ylinen, 1 Hannu Kautiainen, 3 Olavi Airaksinen, 4 Arto Herno, 4 Ulla Tarvainen 1 and Ilkka Kiviranta 2 From the 1 Department of Physical Medicine and Rehabilitation, 2 Department of Orthopaedics and Traumatology, Jyva ¨skyla ¨ Central Hospital, Jyva ¨skyla ¨, 3 Rheumatism Foundation Hospital, Heinola and 4 Department of Physical Medicine and Rehabilitation, Kuopio University Hospital, Kuopio, Finland Objective: To study associations between pain, trunk muscle strength, flexibility and disability in patients with lumbar disc herniation 2 months after surgery. Design: Clinical cross-sectional survey. Participants: 172 operated lumbar disc herniation patients. Methods: Back and leg pain on Visual Analogue Scale, Oswestry Disability Index and Brief Depression Scale were applied to assess the subjectively perceived outcome. Isometric and dynamic strength of trunk muscles and mobility of the lumbar spine were measured to mirror physical impairment. Results: Two months after the operation median leg pain had decreased by 87% and back pain by 81%, respectively. However, moderate or severe leg pain was still reported by 25% and back pain by 20% of the patients. Approximately 30% of the patients perceived moderate or severe disability measured by the Oswestry index. Decreased muscle strength and spine mobility caused functional disability, especially in older patients and patients with postoperative pain. Furthermore, the ratio of trunk extension/flexion strength had changed in favour of the flexion muscles, being 0.98. Greater age and depression were associated with poorer postoperative recovery. Conclusion: Pain, decreased trunk muscle strength and decreased mobility still remained in a considerable propor- tion of patients with lumbar disc herniation 2 months after surgery. Early identification of those patients with restric- tions is essential in order to commence rehabilitation. Key words: lumbar disc surgery, spine mobility, muscle strength, pain, disability. J Rehabil Med 2003; 35: 236–240 Correspondence address: Arja Ha ¨kkinen, Department of Physical Medicine and Rehabilitation, Jyva ¨skyla ¨ Central Hospital, Keskussairaalantie 19, FIN - 40620, Jyva ¨skyla ¨, Finland. E-mail: arja.hakkinen@ksshp.fi Submitted November 12, 2002; accepted March 20, 2003 INTRODUCTION Epidemiological studies have indicated that about 80% of the population experiences back pain during their active lives. In the Mini-Finland Health survey a physician diagnosed sciatica in 5.1% of the 30–64 years old participants (1). Only a minority of patients with sciatica will require surgery (2). In the Central Finland Health Care District the rate of 90 operations per 100,000 inhabitants has been close to the average for the country. In the Netherlands, with a population of about 16 million people, 10,000–11,000 operations are performed each year (3). The main indication for operation is to relieve pain. The success rate for lumbar disc surgery has been reported as 60– 90% (4). Comparison between studies is complicated because surgical indication for the operations vary. However, according to different studies, 10–40% of lumbar disc surgery patients do not have a satisfactory outcome and a proportion of the patients continue to experience severe back or leg pain postoperatively (2–5). According to substantial evidence in recent systematic reviews, work that involves twisting or bending of the trunk, manual heavy material handling or whole body vibration increases the risk of low back disorders. Furthermore, smoking and psychosocial factors, e.g. mental stress and poor job satisfaction, are plausible risk factors both in non-specific low back pain and in sciatic pain (6). In patients with prolapsed intervertebral disc prolonged periods of inactivity due to pain may lead to muscle atrophy in back muscles (7). Posterior lumbar surgery, as such, has also caused muscle and/or nerve damage, resulting in postoperative muscle atrophy (8, 9). The neuromuscular system has an important role to play in the stability and normal function of the lumbar spine (10, 11). Inadequate strength and endurance of back muscles, as well as inadequate mobility of the spine are also identified to be risk factors for low back trouble (12, 13). Adequate function requires sufficient force of the trunk muscles, balance between the agonist-antagonist muscle groups and proper co-ordination (13, 14). Sciatica and surgery-induced pain has also an important role in dysfunction of the lumbar spine. Pain leads to delay in the onset of trunk muscle contraction (14). This change in muscular stabilization decreases the muscular support of the spine and may increase the risk of injury to the spine (11). In addition to the pain relief, the important goal of the operation is to contribute to a rapid return of the patient to their functional condition prior to the episode of sciatica. Fears of causing re-injury, re-herniation or pain may often delay the return to normal activities. The decrease in physical loading of the back to protect the spine after lumbar disc surgery is  2003 Taylor & Francis. ISSN 1650–1977 DOI 10.1080/16501970310005813 J Rehabil Med 35 J Rehabil Med 2003; 35: 236–240