Introduction

Short stems have been developed for some years for preservation of femoral bone stock and achieve physiological proximal loading. Shortening stem length is a merit for bone stock preservation. However, it might lead to reduction of primary stability. We investigated relationship between stem length and primary stability by patient specific finite element analysis (FEA).

Aims

We investigated changes in the axial alignment of the ipsilateral hip and knee after total hip arthroplasty (THA).

[Introduction]

Short tapered wedge-shaped cementless (TW) stems have been widely used for several years. The concept of fixation of TW stem is wedge-fit fixation in the proximal metaphysis. Developmental dysplasia of the hip (DDH) has anatomical abnormality, such as excessive femoral anteversion, short femoral neck length, narrow femoral cavity, or proximal-distal mismatching of the femoral canal. Therefore, Mismatching between stem and bone might be occurred in DDH. We evaluated intramedullary matching of short TW stem for DDH by three dimensional (3D) digital template in order to clarify whether mismatching between stem and bone is seen in DDH implanted short TW stem.

[Objective]

The objectives of this study are to measure the morphometric parameters of pre-operative distal femur in Japanese patients who received TKA, to investigate the differences in distal femoral anatomy between the genders, and to compare the measurements with the dimensions of femoral implants current used in Japan.

[Objectives] Hallux valgus, dorsal sublaxation or dislocation of metatarsophalangeal joints and clawing of the lateral toes are seen frequently in patients with rheumatoid arthritis (RA). Resection arthroplasty of the metatarsophalangeal joints (MTP joints) are widely used to correct these forefoot deformities and the clinical results are almost good. However lateral toes tend to displace dorsally and painful callosity tends to recur. We used the metatarsal shortening offset osteotomy for shortening and dorsal/medial displacement of the prominent metatarsal head. In this report, we introduce the surgical techniques of shortening offset osteotomy and postoperative changes of plantar pressure measured with F-scan system (Tekscan, Inc. ), and review the short term result during 1 to 4 year follow-up.

[Materials and Methods] This study involved 26 feet of 18 patients with RA which were performed with the metatarsal osteotomy for lateral toes and followed more than 1 year (average follow-up 29 months, range 14–46 months). The average age of the 17 women and 1 man was 61 years (range, 51–77 years). The mean duration from the onset of RA to operation on the forefoot was 17 years (range, 7–42 years). Skin incision was placed on the dorsum of the foot and the extensor digitorum brevis and longus were severed (or elongated). After reposition of MTP joint, transverse osteotomy of distal fifth of the lateral metatarsal bone was performed with resection of few millimeters length metaphysial bone. Cortical bone of the distal end of the proximal stump was chiseled into a small rod between two ditches with rongeur and then the rod was put into medullary canal mortise of distal stump. This procedure make offset shift of metatarsal head medially or dorsally. Swanson implant arthroplasty, distal osteotomy was performed on the great toe. Postoperative clinical and radiological results were evaluated with AOFAS rating system. We measured dynamic plantar pressure before and one year after operation in one representative case.

[Results] At the time of follow-up, the mean AOFAS score was 80 points (59–95) and the mean pain score was 36 points. The recurrence of painful callosity was one case. Nevertheless, the range of motion of the MTP joint remained low: 30 degrees and less in 16 feet (62%) including 3 bony ankylosis of MTP joints. There was no nonunion case. [Discussion]

Resection arthroplasty has been accepted as the treatment of choice for forefoot deformities in RA patients. Recent advance of drug therapy against RA encouraged us to preserve the joint in correction of forefoot deformities. Our technique aimed at preservation of the function of the MTP joints and is suitable for mild deformities in which only one or two rays are involved. Furthermore it is easy to correct the deformity of spray foot and reduce the plantar prominence of metatarsal head. This study revealed the good clinical result in short term follow-up. Although the long term result must to be waited, this method is one of recommendable options for RA patients with forefoot deformities.

In an attempt to repair articular cartilage, allograft articular chondrocytes embedded in collagen gel, were transplanted into full-thickness defects in rabbit articular cartilage. Twenty-four weeks after the transplantation, the defects were filled with hyaline cartilage, specifically synthesising Type II collagen. These chondrocytes were autoradiographically proven to have originated from the transplanted grafts. Assessed histologically the success rate was about 80%, a marked improvement over the results reported in previous studies on chondrocyte transplantation without collagen gel. By contrast, the defects without chondrocyte transplantation healed with fibrocartilage. Immunological enhancement induced by transplanted allogenic chondrocytes or collagen was not significant at eight weeks after treatment, so far as shown by both direct and indirect blastformation reactions. Thus, allogenic transplantation of isolated chondrocytes embedded in collagen gel appears to be one of the most promising methods for the restoration of articular cartilage.