Purpose: Posterior arthroscopy is generally performed by alternating visual control using the optic introduced via one of the anterior portals which is slid into the slit via the contralaeral posterior compartment. These two “crossed” posterior portals provide access to the posterior part of the menisci and to the condyle but remain oblique. Any sagittal partition separating the posterior compartments limits visual and instrument access to the posterior part of the articular cavity. The purpose of this work was to describe a novel back-and-forth technique for posterior arthroscopy which allows posterior access to the central pivot.

Material and methods: The conventional posteromedial access was used. The optic was introduced to visualise the posterior cruciate ligament and the posterior partition, and when in contact with it, to push it forward. The optic was then replaced by a round-headed instrument to perforate the partition above the posterior cruciate ligament and penetrate into the lateral compartment. The instrument was pushed against the posterolateral wall determining the point of the corresponding portal. A motorised knife was introduced into the end of the canula then brought into the medial compartment. The posterior partition was resected, creating a single posterior space which could be examined under direct visual control. During an anatomy study, we examined the relationship between the noble elements in the popliteal fossa and the different instruments used during this procedure. Fifteen patients with villonodular synovitis underwent exclusively arthroscopic synovectomy using this approach.

Results: We did not have any case of vessel or nerve injury and had no recurrence at mid-term. Postoperatively, patient comfort was much better than after arthrotomy synovectomy.

Discussion: This difficult method requires an excellent knowledge of the position of the different anatomic elements in the popliteal fossa close to the posterior part of the articulation. This combined posterior approach facilitates access to the posterior part of the articular cavity of the knee and offers a new approach to the posterior cruciate ligament as well as broader indications for arthroscopic synovectomy with more complete resection. It does not allow access to the submeniscal folds nor to the fibulotibial articulation.

Limited success in regenerating large bone defects has been achieved by bridging them with osteoconductive materials. These substitutes lack the osteogenic and osteoinductive properties of bone autograft. A direct approach would be to stimulate osteogenesis in these biomaterials by the addition of fresh bone-marrow cells (BMC).

We therefore created osteoperiosteal gaps 2 cm wide in the ulna of adult rabbits and either bridged them with coral alone (CC), coral supplemented with BMC, or left them empty. Coral was chosen as a scaffold because of its good biocompatibility and resorbability. In osteoperiosteal gaps bridged with coral only, the coral was invaded chiefly by fibrous tissue. It was insufficient to produce union after two months. In defects filled with coral and BMC an increase in osteogenesis was observed and the bone surface area was significantly higher compared with defects filled with coral alone. Bony union occurred in six out of six defects filled with coral and BMC after two months. An increase in the resorption of coral was also observed, suggesting that resorbing cells or their progenitors were present in bone marrow and survived the grafting procedure. Our findings have shown that supplementation of coral with BMC increased both the resorption of material and osteogenesis in defects of a clinical significance.