Introduction A wide range of stress-shielding phenomena following THA have been described in the past 20 years. Bone densitometry (DXA) stars as a golden standard in evaluating bone stock and bone density redistribution after total hip replacement.

In this study, DXA scan was employed to evaluate and compare the behaviour of different femoral components including a recently developed stemless implant which features complete stress transfer over the proximal femur.

Methodology A total of 120 patients, operated with six different femoral implants, were included in the present study. Five of these stems are widely commercially available (ABG, CFP, IPS, Mayo, Zweymueller) and present different patterns of stress distribution. The sixth is a custom made implant and features a pronounced lateral flare and complete femoral neck preservation. Rationale of this design is to obtain full load transfer on the proximal femur.

Average interval between the operation and the DXA exam was 3 years, each group included 20 patients. Bone mineral density was measured by DXA in the seven Gruen femoral regions (ROI), using the software metal removal (Hologic QDR 4500 W, MA-USA).

Results Differences in bone density were found in each group as well as between different groups. Significant differences (p< 0.001) were found between the stemless implant and the other five groups in zone I, IV and VII.

CFP, IPS and ABG groups showed decreased bone density in ROI I, while Mayo, IPS, ABG and Zweym-ueller were osteopenic in ROI VII. An increased bone density in ROI IV was found in Zweymueller, Mayo, ABG and IPS groups.

Conclusion Our data suggest that a conservative stemless implant with complete proximal load transfer, produces a homogeneous and more physiologic redistribution of bone density, allowing maintenance of proximal periprosthetic bone stock.

Although various treatment options are available, which include shaving, microfractures, abrasion arthroplasty osteochondral allografts and autografts, chondrocyte grafts and unicondylar prostheses, symptomatic articular cartilage defects represent a therapeutic challenge.

Since November 2002, as a non-biological answer to the problem, we started using synthetic cartilage implants made of polyvinyl alcohol- hydrogel (PVA – H) (SaluCartilage). This is a transparent synthetic polymer with a molecular weight of 308,000 daltons and 20% of water content, available in cylindrical shape of various diameters. Following the second part of the OATS technique, under arthroscopic control and by mini-arthrotomy, or completely arthroscopically assisted, the cylindrical implant is inserted, using press-fit technique, into previously punched out and dilatated osteochondral defects.

Our patients, whose mean age was 56 years (range 48–68 years) have been post-operatively reviewed clinically and by serial MRI exams. Patients showed significant improvement over pre-operative values in the IKDC score, with an average increase of 20 points. Follow-up MRI images revealed a normal healing process, without signs of osteolysis or wear.

As complications we had one case of implant dislocation 1 year after surgery and one case of progressive loosening due to osteoarthritic disease, both of which have required a knee prosthesis.

Our experience has led us to emphasise the use of this type of treatment only in cases that fullfil precise indications: (a) Third and fourth degree chondral or osteochondral symptomatic defects; (b) focal unicompartmental defects with 15 mm maximum extent; (c) patient’s age limited from fourth to seventh decade of life; and (d) absence of angular deformities or articular instabilities.

The synthetic cartilage resurfacing technique has the advantages of no donor defect, one short-step surgical procedure, immediate weight-bearing and no extensive rehabilitation programme. Early results of first 15 patients are being presented, expecting a longer observation follow-up study.

Aims: description of results obtained with a single radius TKA design. Matherials and methods: In 1999 we started implanting single-radius TKA design (Scorpio–Osteonics). Between January 1999 and April 2002 we have implanted 211 TKA, 15 bilateral, with 24 months average follow-up (range 3–36 months). This type of prosthesis is based on the concept that the normal knee rotates about a single axis – the transepicondylar axis. This reduces mid-flexion instability, improves patello-femoral tracking and decreases the occurrence of anterior knee pain. Results: Knee Society score has improved to 90 points post-op from 39 points pre-op and function evaluation from 44 to 82 points. We had 128 cases excellent (65.6%), 40 good (20.5%), 24 fair (12.4%) and 3 poor (1.5%). X-ray follow-ups have revealed in 83% of cases knee angulation between 2° from neutral, in 11% a varus deviation between 3° and 5° and in 6% a valgus deviation between 3° and 5°. Radiolucencies have been found in 18 patients (9.23%). Conclusions: Scorpio single-radius prosthesis has permitted a full and early recovery of knee function. Bone cuts, especially the tibial one, are reduced. Anterior knee pain is dramatically reduced and is associated with incremented range of motion and improvement in knee stability, especially in the mid flexion. These short term results are really encouraging, but need to be confirmed by future follow-up studies.