Endoprosthetic arthroplasty of the ankle joint. A clinical and radiological follow-up.

Eighteen ICLH ankle arthroplasties in 16 patients were followed up 15 to 52 months postoperatively (mean 36 months) by a review of the records, and clinical and radiological examinations. Five arthroplasties were performed for osteoarthrosis, 13 for rheumatoid arthritis. The overall clinical result was rated excellent in 2, good in 8, fair in 6, and poor in 2 joints. In osteoarthritic joints the results were somewhat poorer, no patient obtaining a rating of excellent but 2 of good, 2 of fair, and one of poor. Radiolucent zones greater than 2 millimeters were seen around the tibial component in 7 cases. Loosening defined as radiographic signs of movement between the prosthetic components and bone was present in 4 cases. The high occurrence of obvious loosening and large radiolucent zones indicates that mechanical problems will be encountered frequently in the future. From the results of this study it is concluded that ankle arthroplasty has a definite place in the treatment of severe arthritis in rheumatoid patients.

Hardness of the subchondral bone of the patella in the normal state, in chondromalacia, and in osteoarthrosis.

The hardness of bone is its property of withstanding the impact of a penetrating agent. It has been found that articular degenerative changes in, for example, the tibia (knee) are combined with a decrease in the hardness of the subchondral bone. In this investigation the hardness of subchondral bone in chondromalacia and osteoarthrosis of the patella has been analysed and compared with normal subchondral bone. Using an indentation method originally described by Brinell the hardness of the subchondral bone was evaluated in 7 normal patellae, in 20 with chondromalacia and in 33 with osteoarthrosis. A microscopic and microradiographic study of the subchondral bone was carried out simultaneously. Hardness was lowest in the normal material. The mean hardness value beneath the degenerated cartilage differed only slightly from that of the normal material, but the variation of values was increased. The hardness in bone in the chondromalacia area was lower than the hardness in bone covered by surrounding normal cartilage. The mean hardness value in bone beneath normal parts of cartilage in specimens with chondromalacia was higher than the mean hardness value of the normal material. In the microscopic and microradiographic examination it became evident that there was a relationship between trabecular structure and subchondral bone hardness; high values: coarse and solid structure; low values: slender and less regular structure.

Cervical collars in rheumatoid atlanto-axial subluxation: a radiographic comparison.

Atlanto-axial subluxation occurs with a frequency varying from 6% to 45% in rheumatoid arthritis. Most patients are treated conservatively with a cervical collar. The effectiveness of different cervical collars in inhibiting anterior atlanto-axial subluxation was tested in 11 patients with classical rheumatoid arthritis. None of the collars had any major influence in inhibiting anterior subluxation of the atlas in maximal flexion. Furthermore, the harder collars with a stable cervical stand forced the atlas to subluxate anteriorly in some of the patients.

A study of the arterial supply of the patella in the normal state, in chondromalacia patellae and in osteoarthrosis.

The arterial supply to the patella has been studied in 21 specimens. Fifteen were obtained at autopsy and six at amputation. Nine of the specimens were normal, six were diagnosed as chondromalacia patellae and six as osteoarthrosis. Micropaque was injected into the arteries, and the Spalteholtz clearing technique was used. Radiography was also performed. In addition to previously reported observations, arteries were found to penetrate into the patella from the interior of the quadriceps tendon, from the synovial tissue and from the medial and lateral retinaculae. Moreover, it was found that with increasing degree of cartilage destruction the arterial pattern within the patella became disturbed and irregular with formation of anastomoses.

Intramedullary pressure of the patella in Chondromalacia.

Degenerative changes in load-bearing joints are often combined with altered intramedullary circulation. This may cause an alteration in intramedullary pressures. It has been said that articular symptoms are connected with a change in intramedullary pressures being high they are suspected to cause pain. In this investigation the intramedullary pressure has been evaluated in chondromalacia and osteoarthrosis of the patella. A comparison has been made with normal patellae. A biopsy needle was drilled into the intramedullary bone of the patella and connected with a registering unit. In a control group an average value of 19 mm Hg was registered. In the condromalacia group the mean intramedullary pressure was 44 mm Hg and in osteoarthrosis 37 mm Hg.

Total hip replacement with a trunnion bearing prosthesis. Biomechanical principles and preliminary clinical results.

The biomechanics are presented of a bushing principle forming the basis for a trunnion bearing prosthesis in total hip replacement. The femoral stem is equipped with a trunnion on to which a cylindrical plastic sleeve is applied. On top of this a metal casing is placed which forms the femoral head. On flexion-extension this remains stationary in the acetabular cup and motion occurs between the trunnion and the cylindrical sleeve. Friction between head and cup is reduced to a minimum, decreasing the risk of loosening. A follow-up study of 61 hips replaced by the trunnion bearing prosthesis was performed 2.5 years postoperatively. Eighty-eight per cent were considerably improved. There was one deep infection and two femoral stem loosenings.

An alternate method for posterior fixation in anterior and inferior atlanto-axial dislocation.

A modification of common methods is described for fixation of anterior and inferior atlanto-axial dislocation (AAD and IAD). In AAD a wire is passed around the atlas arch and knotted around the spinous process of the axis in a way that a figure 8 arrangement is achieved as seen in the lateral view. In IAD a wire is passed through holes in the occiput and knotted around the spinous process of the axis. A rectangular bone graft is inserted between the occiput and the spinous process of the axis, thus preventing further inferior dislocation. In both methods methyl methacrylate and bone grafts are as a rule added for further long-time stabilization. The methods have been used in 15 cases of AAD and in three cases of IAD. On radiologic examination with attention focused on the immediate postoperative fixation the follow-up time has been three months. The long-time results of fixation have been recorded with a follow-up time of six years. The fixation proved to be satisfactory in 14 patients with AAD and in the three patients with IAD. The clinical results were good in the 14 patients with AAD and in the three with IAD.

Resurfacing arthroplasty of the hip. Biomechanical, morphological, and clinical aspects based on the results of a preliminary clinical study.

As an alternative in total hip replacement the so called resurfacing arthroplasty of the hip is gaining wider acceptance. The procedure can be said to be a modernisation of the original Smith-Pedersen operation and is suggested in young people with degenerative hip disease, congenital hip dysplasia or Perthes' disease. The advantages are that the femoral head and neck are retained and thus no femoral stem prosthesis is necessary. The greatest disadvantage is that in case of socket loosening a secondary operation might not remain as successful as could the initial operation with a socket which is not as large as those recommended for the resurfacing procedure. In this presentation a preliminary report of a one-year material is presented together with a presentation of advantages, disadvantages, and the biomechanical appraisal of resurfacing of the hip. Fifteen patients with 17 hips have been operated and followed-up and by using the Merle d'Aubigné evaluation there was an improvement of some 3--4 points in pain, walking, and total motion. Patient opinion indicated 80% satisfaction. The management of two serious complications is also described.

The biomechanical influence of traction on the cervical spine.

The effects exerted on the cervical spine by a traction of 150 N was studied by means of an improved radiographic technique. The technique is presented together with results from a study including fifteen test subjects with and without clinical symptoms of neck pain. In a minority of discs a widening not exceeding 1 mm was seen. This widening was not correlated to presence of roentgen signs indicating degenerative disease of the disc nor to clinical symptomatology.