Posture control after lumbar microdiscectomy

INTERVENTION: 1. Transmuscular surgical approach versus classic paramedian approach to the disc herniation at surgery 2. Early postoperative physiotherapy, starting two weeks postoperatively, and consisting of an individualised program with standardised goals versus 'conservative' treatment: no physiotherapy in the first six weeks post‐operation and after six weeks only when indicated Follow up is one year for all four arms. CONDITION: Sciatica caused by a lumbar disc herniation ; Musculoskeletal Diseases ; Other intervertebral disc disorders PRIMARY OUTCOME: Muscle control (assessed by postural balance test and sit‐to‐stand test), assessed in the lab at two weeks, eight weeks and six months post‐operatively. SECONDARY OUTCOME: Comfort:; 1. Back pain; 2. Sciatica; 3. Functional status; 4. Return to work; ; Secondary outcome measures are assessed by standardised patient questionnaires preoperatively and at two weeks, eight weeks, six months and one year postoperatively. INCLUSION CRITERIA: 1. One level disc herniation, either L4‐L5 or L5‐S1, explaining symptoms and representing operative indication. Purely median disc herniations are excluded. 2. Age: 18 ‐ 60 years, either sex 3. Living within 30 km perimeter of the hospital 4. Informed consent signed