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The assessment of a patient with chronic hip pain can be challenging. The differential diagnosis of intra-articular pathology causing hip pain can be diverse. These includes conditions such as osteoarthritis, fracture, and avascular necrosis, synovitis, loose bodies, labral tears, articular pathology and, femoro-acetabular impingement. Magnetic resonance imaging (MRI) arthrography of the hip has been widely used now for diagnosis of articular pathology of the hip. A retrospective analysis of 113 patients who had MRI arthrogram and who underwent hip arthroscopy was included in the study. The MRI arthrogram was performed using gadolinium injection and reported by a single radiologist. The findings were then compared to that found on arthroscopy. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy and 95% confidence interval were calculated for each pathology. Labral tear-sensitivity 84% (74.3-90.5), specificity 64% (40.7-82.8), PPV 91% (82.1-95.8), NPV 48% (29.5-67.5), accuracy 80%. Delamination -sensitivity 7% (0.8-22.1), specificity 98% (91.6-99.7), PPV 50% (6.8-93.2), NPV 74% (65.1-82.2) and accuracy 39%. Chondral changes-sensitivity 25% (13.3-38.9), specificity 83% (71.3-91.1), PPV 52% (30.6-73.2), NPV 59% (48.0-69.2) and accuracy 58%. Femoro-acetabular impingement (CAM deformity)-sensitivity 34% (19.6-51.4), specificity 83% (72.2-90.4), PPV 50% (29.9-70.1), NPV 71% (60.6-80.5) and accuracy 66%. Synovitis-sensitivity 11% (2.3-28.2), specificity 99% (93.6-100), PPV 75% (19.4-99.4), NPV 77% (68.1-84.6) and accuracy 77%. Our study conclusions are MRI arthrogram is a useful investigation tool in detecting labral tears, it is also helpful in the diagnosis of femoro-acetabular impingement. However, when it comes to the diagnosis of chondral changes, defects and cartilage delamination, the sensitivity and accuracy are low.

Among the various types of osteotomy, most have been designed and applied to hip joints. Because the hip joint supports the largest body load and has special characteristics from the viewpoint of structural function, it is prone to various diseases and degenerative conditions. Therefore, it has been said that a surgeon who can control the hip joint is able to master the field of orthopedics. Based on past experience, hip surgeons have seen that articular cartilage regenerates after osteotomy employed to treat osteoarthritis in the hip. The regeneration manifests on X-ray films as widening of the joint space after surgery. Such regeneration of articular cartilage has been confirmed by magnetic resonance imaging (MRI) and arthroscopy and by biopsy, although histologically this cartilage is not exactly the same as the original articular cartilage. In cases of osteonecrosis of the femoral head, if the progression of collapse is prevented by a transtrochanteric rotational osteotomy as well as a transtrochanteric curved varus osteotomy, necrotic lesions are replaced by appositional new bone formation, which subsequently results in normal bone and bone marrow tissue. This has been confirmed by radiography, MRI, and histology. In other words, when the progression of collapse and subsequent joint deformity are prevented by osteotomy, which transposes the normal articular surface with normal bone trabeculae to the weight-bearing portion, the necrotic bone trabeculae are replaced by viable bone. If joint realignment can be achieved by osteotomy, thus spreading and averaging the load, articular cartilage is regenerated. This phenomenon can be observed not only in hip joints but also in the knee and other joints. Although regenerative medicine has recently seen a sudden resurgence of popularity, there seems to be a view that its use is limited to tissue regeneration by transplantation of tissue cultured in vitro using embryonic stem cells or somatic stem cells. However, I believe that regeneration of tissue by stimulating primitive mesenchymal stem cells already present in the living body and by providing an environment suitable for the regeneration of the required cells is a natural form of regenerative medicine. This practice has long been used in the domain of orthopedics. Thus, it is obvious that joint regeneration by osteotomy is one representative type of regenerative medicine. Research on bone fracture healing mechanisms and heterotopic bone formation has been conducted since the eighteenth century, when it was first recognized that bone tissue has particularly strong regenerative potential. The concept of bone induction was formulated more recently. After M.R. Urist, one of the advocates of this concept, first reported the existence of bone morphogenetic protein (BMP), research on BMP advanced rapidly during the second half of the twentieth century. In 1964, Till and McCulloch carried out bone marrow transplants in lethally irradiated mice and observed the formation of many cell colonies in the spleens of these mice. They called them “colony-forming units” (CFU). A CFU is a colony formed by a single hematopoietic stem cell. Their dissertation is thought to have been the first to establish the stem cell concept. Surprisingly, however, in 1962 C.A.L. Bassett (Orthopedic Research Laboratories, Department of Orthopedic Surgery, Colombia University College of Physicians and Surgeons) had already presented an instructional course lecture at the American Academy of Orthopaedic Surgeons (AAOS) in which he stated that induction of cartilage, bone, and tendinous fiber tissue can be observed during the culture of immature mesenchymal stem cells by changing features of the culture environment, such as compaction and tension as well as the oxygen concentration. Thus, he had already clarified the fact that cartilage, bone, and tendon tissue differentiate from mesenchymal stem cells when the culture environment is changed.