Purpose: Ulnolunate disorders secondary to fracture of the radius generally result from inversion of the distal radioulnal index due to the relative shortening of the radius creating a conflict between the head of the ulna and the proximal anterior articular surface of the semilunate and cartilage impingement. Arthroscopy can often provide the diagnosis and minimally invasive treatment.

Material and methods: We reviewed a series of 32 patients, 15 men and 17 women, mean age 66 years (45–82). All presented sequelae of a fracture of the lower quarter of the radius with axial impaction. The ulnar variance was 2.7 mm (2–5). Time from initial fracture to arthroscopic resection was nine months (2–26). All patients presented pain, which was moderate and permanent in 19 and disabling in 13. Overall muscle force was reduced by 50% compared with the healthy side. Motion was limited due to the callus often associated with healing of these fractures. Patients underwent arthroscopy in an outpatient setting under locoregional anaesthesia. The arthroscope was introduced via a 3–4 radiocarpal portal allowing exploration of the joint space. Surgical treatment consisted in milling for partial distal resection of the ulnar head (6R radiocarpal portal). Wrist motion was restored in all cases.

Results: Mean follow-up was 39 months (18–54). Wrist motion was restored immediately in all cases. Pain at the radioulnar joint persisted in two patients. For 26 patients, the preoperative pain disappeared immediately. Muscle force improved compared with the preoperative level but did not reach the level of the healthy side.

Discussion: Arthroscopic treatment of ulnolunate impingement has proven efficacy and safety. It should however be reserved for cases with an inverted distal radioulnar index measuring less than 5 mm. If the ulnar variance is larger, we prefer ulnar osteotomy to shorten the bone. Other techniques are reserved for cases where the distal radioulnar joint is damaged.

The changes occurring in ligamentum flavum in lumbar spine stenosis are a matter of long–standing controversy. More recently, some studies showed that the posterior spinal structures, including hypertrophied ligamentum flavum, play a major role in the pathogenesis of the lumbar stenosis.

To investigate the pathogenesis of the degenerative changes of the ligamentum flavum occurring in lumbar spine stenosis, yellow ligament cells from patients with lumbar spine stenosis were cultured for the first time and subjected to biochemical, histochemical and immunohistochemical study.

Samples of ligamentum flavum were collected from 4 patients undergoing surgery for lumbar stenosis (mean age 47.2 years). Cell cultures were obtained from each patient and maintained in Dulbecco’s modified essential medium-10% fetal calf serum. Cell characterization was histochemically (Gomori’s and von Kossa staining), immunohistochemically (anti-type I, -type II, -type III and -type X collagen, anti-S100 protein, anti-fibronectin, anti-osteonectin and anti-osteocalcin), biochemically (cAMP activity after human parathyroid hormone stimulation) assessed. Samples collected from 2 age-matched patients who underwent surgery for lumbar fractures were used as controls.

Stenotic ligamentum flavum cells expressed high levels of alkaline phosphatase activity and produced a mineralized matrix rich in type I, type III and type X collagen, fibronectin, osteonectin, and osteocalcin. Stimulation with parathyroid hormone increased intracellular cAMP concentration. These findings indicate that there was significant evidence of osteoblast-like activity in these cells. Staining for type II and type X collagen, and S-100 protein reflected the proliferation of hypertrophic chondrocyte-like cells, confirmed with the co-localization of alkaline phosphatase and collagen type II. Cultures from control patients showed nor hypertrophic chondrocytic nor osteoblastic features. Our data demonstrated the presence of hypertrophic chondrocytes with an osteoblast-like activity in human stenotic ligamentum flavum. The osteoblast-like activity could have a role in the pathophysiology of the heterotopic ossification of ligamentum flavum in lumbar spine stenosis.

The material most widely used in orthopaedics is hydroxyapatite (HA), anyway many differences are still present between synthetic HA and biological HA. The aim of this study was to compare adhesion, proliferation and differentiation of human osteoblast-like cells on hydroxyapatite discs with different porosity and on plastic cultures.

Human osteoblast-like cells were isolated from 4 young patients (mean age 24.5 years old), treated with collagenase and maintained in Dulbecco’s modified essential medium-10% fetal calf serum. Cells were plated on hydroxyapatite discs with 3 different porosities (35%, 35–55% e 55%) and on plastic cultures used as control. The proliferation was determined by the MTT colorimetric method, and alkaline phosphatase (ALP) activity was measured by a spettrophotometric method. Type I collagen and osteonectin production were demonstrated with fluorescence microscopy and osteoblast adhesion was studied by scanning electron microscopic (SEM) analysis. Results were analysed by one-way analysis of variance (ANOVA).

Osteoblast proliferation on HA was three- to six-fold lower then on plastic. At 28 days, 2141 (± 350) cells/well grew on the most porous disks, with highly significant differences from controls. The ALP production was 2–3 fold lower on HA than on plastic. In the most porous disks, the mean ALP activity was of 2.95 (± 0.07) UI/well after 28 days, higher than in the other two groups. The type-I collagen and the osteonectin fluorescence reaction evidenced a cytoplasmic and a matrix labeling on HA at different porosities. SEM analysis showed osteoblasts with a flattened morphology and only few of them were metabolic active.

At 21 and 28 days, proliferation rate and ALP activity on the three HA cultures were significantly different (p< 0.05). A decrease in cell population and increased ALP activity were observed on the most porous material, and high proliferation and poor differentiation rates on the less porous disks.