Purpose Transforaminal endoscopic discectomy (TED) minimises paraspinal muscle damage. The aim of this trial was to compare clinical outcomes of TED to Microdiscectomy (Micro). Methods 143 patients, age 25-70 years and \115 kg, with single level lumbar prolapse and radiculopathy, were recruited and randomised. 70 received TED under conscious sedation and 70 Micro under general anaesthesia. Oswestry Disability Index (ODI), visual analogue scores (VAS) of back and leg pain, and Short Form Health Survey indices (SF-36) were measured preoperatively and at 3, 12 and 24 months. Results All outcome measures improved significantly in both groups (p \ 0.001). Affected side leg pain was lower in the TED group at 2 years (1.9 ± 2.6 vs 3.5 ± 3.1, p = 0.002). Hospital stay was shorter following TED (0.7 ± 0.7 vs 1.4 ± 1.3 days, p \ 0.001). Two Micro patients and five TED patients required revision giving a relative risk of revision for TED of 2.62 (95% CI 0.49-14.0). Conclusions Functional improvements were maintained at 2 years in both groups with less ongoing sciatica after TED. A greater revision rate after TED was offset by a more rapid recovery.

We reviewed 212 consecutive patients with adolescent idiopathic scoliosis who underwent posterior spinal arthrodesis using all pedicle screw instrumentation in terms of clinical, radiological and Scoliosis Research Society (SRS)-22 outcomes. In Group 1 (51 patients), the correction was performed over two rods using bilateral segmental pedicle screws. In Group 2 (161 patients), the correction was performed over one rod using unilateral segmental pedicle screws with the second() rod providing stability of the construct through two-level screw fixation at proximal and distal ends. The mean age at surgery was 14.8 years in both groups. Comparison between groups showed no significant differences with regard to age and Risser grade at surgery, pre- and post-operative scoliosis angle, coronal Cobb correction, length of hospital stay and SRS scores. Correction of upper thoracic curves was significantly better in Group 1 (p = 0.02). Increased surgical time and intra-operative blood loss was recorded in Group 1 (p < 0.001 and p = 0.04, respectively). The implant cost was reduced by mean 35% in Group 2 due to the lesser number of pedicle screws. Unilateral and bilateral pedicle screw techniques have both achieved excellent deformity correction in adolescent patients with idiopathic scoliosis, which was maintained at two-year follow-up. This has been associated with high patient satisfaction and low complication rates.

We show that Stable Matching problems are the same as problems about stable configurations of X-networks. Consequences include easy proofs of old theorems, a new simple algorithm for finding a stable matching, an understanding of the difference between Stable Marriage and Stable Roommates, NTcompleteness of Three-party Stable Marriage, CC-completeness of several Stable Matching problems, and a fast parallel reduction from the Stable Marriage problem to the ' Assignment problem.

We propose a framework for studying bottom-up restructuring heuristics for binary search trees. We identify the key role played by depth-reducing rules in obtaining logarithmic amortized cost per access. We show that splaying is by no means the only heuristic that offers logarithmic amortized cost. ᮊ 1996 Academic Press, Inc.

E r n s t W. M a y r Ashok S u b r a m a n i a n C o m p u t e r Science D e p a r t m e n t Stanford UniversityS t a n f o r d , C A 94305-2140Fachbereich Informatik (20) J . W. G o e t h e Universitat F r a n k f u r t a m Main 11West G e r m a n y U S A AbstractWe develop a method for non-trivially restricting fanout in a circuit. We study the complexity of the Circuit Value problem and a new problem, Network Stability, when fanout is limited. This leads to new classes of problems within P. We conjecture that the new classes are different from P a n d incomparable to n/C. One of these classes, CC, contains several natural complete problems, includingCircuit Value for comparator circuits, Lex-first Maximal Matching, and problems related to Stable Marriage and Stable Roommates. When fanout is appropriately limited, we get positive results: a parallel algorithm for Circuit Value that runs in time about the square root of t h e number of gates, a linear-time sequential algorithm for Network Stability, and logspace reductions between Circuit Value and Network Stability.