Purpose: Multiple deformations of the lower limbs are common orthopaedic complications of central nervous system disease. Assessment is difficult. Intrathecal Liorésal® was proposed for the patients to establish the relative effects of spasticity and musculotendinos retraction and define a medico-surgical therapeutic strategy.

Material and methods: Between January 1999 and December 2000, 31 patients consulted for persistent knee flexion. Baclofen tests (75 – 100 μg Baclofen intrathecal) were performed in ten patients because the relative contribution of spasticity and retraction was difficult to assess. The anti-spasticity effect was observed within the first hour, with a maximal effect between the second and fourth hour. Motor function, joint motion, and function were tested during this time interval. The test was repeated approximately three days later, sometimes with higher doses depending on the level of the anti-spastic effect. Residual orthopaedic limitations were explained by musculotendinous retractions.

Results: For the ten evaluated patients, three presented musculotendinous retractions amendable by surgical treatment (tendon lengthening, proximal disinsertion), sometimes in combination with arthrolysis. For the seven patients who had hypertonic spastic contractions, medical treatment was given with, for three patients, continuous intrathecal Lioresal via pump delivery. There was a correlation between the deformation assessed after the test and the test conducted under general anaesthesia during the procedure in all patients.

Discussion: Other methods for evaluating orthopaedic deformities of the lower limbs can be used. Selective motor blocks using local anasethetics are generally reserved for patients with localised stiffness or when it may be difficult to achieve in certain patients (hip flexion). Mobilisation under general anaesthesia is another solution, but does not allow an assessment of functional gain, particularly if the goal is walking. The intrathecal Baclofen test not only allows an accurate assessment of orthopaedic retraction, but also an assessment of the functional impact of the spasticity, sometimes useful for verticalisation or walking.

Conclusion: The Baclofen intrathecal test is a simple test with a particular place in the preoperative and functional assessment of neuro-orthpaedic stiffness of the lower limbs.

Purpose: Few studies have been devoted to neurogenic paraosteoarthorpathy (PAOn). We characterised the expression of genes specific for osteoblastic and chon-drocytic phenotypes using the osteomy wedge and non-mineralised tissue near the osteotome.

Material and methods: Osteotomy fragments and non-mineralised tissue near the osteotomy were obtained during surgery performed in 25 patients. The explants were cultured for 56 days. We searched for the messenger RNA of the principal markers of osteoblastic, chon-drocytic, and adipocytic phenotypes, as well as certain specific proteins. Serial cryotome sections were stained for histology and immunolabelling tests.

Results: Cells issuing from the osteotomy fragment and neighbouring tissues formed structures that miner-alised in culture. The following osteoblast markers were observed: alkaline phosphatase (bone isoform), osteo-calcin, Cbfa1, type 1 collagen; for chondrocytes: type II collagen, aggrecane; type X collagen as well as VEGT demonstrating the presence of hypertrophic chondrocytes.The adipocyte-specific transcription factor PPAR 2 was also found in the two cultures. The proportions and chronological expression of these markers were slightly different for the two tissues. Ex vivo study demonstrated the typical sequence of enchondral type bony formation from non-osseous cell populations.

Discussion: This work provided the first characterisation of non-mineralised tissue near osteotomy. It also provided clear indications concerning the history of ectopic bone formation. The osteochondrogenic potential of connective tissue lying close to an osteotomy has not been reported previously. The persistence of this potential could explain recurrence after resection. The observation that this potential is suppressed in vivo but expressed in vitro opens a new avenue of research concerning the mechanisms controlling bone formation.

Conclusion: The culture model developed in this study provides a means of studying factors determining the outcome of cell populations implicated in the formation of neurogenic paraosteoarthropathies.