Anders Lindstrand

Roentgen stereophotogrammetric analysis as a predictor of mechanical loosening of knee prostheses

The tibial components in 143 patients with total knee replacements performed before 1988 were assessed for micromotion using roentgen stereophotogrammetric analysis (RSA) over a period of 13 years. The fixation of the prostheses remained clinically sound in all cases, although revision had been required for other reasons in seven. In a second group taken from all cases with RSA available on our full database to 1990, 15 tibial components had been followed by RSA from the insertion until, 1 to 11 years after the initial arthroplasty, they were revised for mechanical loosening of the tibial component; 12 of these comprised all the loosenings in the base group, thus making a total of 155 consecutive cases, while an additional three were inserted after the base material had been compiled. The mean migration in the first group was about 1 mm at one year, but subsequent migration was slower, reaching a mean of about 1.5 mm after ten years. About one-third migrated continuously throughout follow-up, while two-thirds ceased to migrate after one to two years. In the revision group, 14 components had migrated continuously and at one year significantly more than those in the first group. One revision case lacked the crucial one-year follow-up and could not be classified. These findings suggest that mechanical loosening begins early in the postoperative period. Clinical symptoms which necessitate revision, seen at this stage in 20% of abnormally migrating tibial components, may not appear until up to ten years after the operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Soccer after anterior cruciate ligament injury - An incompatible combination? A national survey of incidence and risk factors and a 7-year follow-up of 310 players

All players in Swedish soccer teams are required to have insurance in the same company. From the archives of the insurance company, all 3,735 injuries reported in 1986 in 188,152 Swedish soccer players were reviewed. Of these, 937 were knee injuries. All players were asked by mail to fill in a questionnaire and 83 percent replied. The patient records from the different hospitals were requested. The anterior cruciate injuries represented one third of the reported knee injuries. The relative risk of sustaining an anterior cruciate ligament injury was increased in female players, in elite players, and in players in the forward position. The odds ratios were 1.6 (1.3-2.1), 3.3 (1.7-6.1) and 1.8 (1.4-2.5), respectively. The injuries occurred at a younger age in females than in males. 50 percent of the injured players were treated with anterior cruciate ligament surgery, predominantly as a reconstructive procedure, with use of a patellar tendon transplant. 30 (20) percent of the players with anterior cruciate ligament injury were active in soccer after 3 (7) years, compared to 80 (50) percent of an injured control population of soccer players. None of the elite players was active at the same level after 7 years. A comparison of anterior cruciate ligament-injured players, whether treated by surgical reconstruction or not, revealed no difference with regard to the proportion of players still playing soccer after 7 years.

A stabilometric technique for evaluation of lower limb instabilities

Stabilometry is a technique designed to register pos tural equilibrium control. This investigation used a com puterized strain gauge force plate to measure sway movements in the frontal plane with the patient standing on one leg. Fifty-five young healthy individuals were studied as a reference group and to determine the reproducibility of the method. The clinical population consisted of 14 patients with unilateral injuries to the lateral ligaments of the ankle. These were measured, both with and without an ankle brace. The different parameters used to describe the body sway could well discriminate between the injured and the uninjured leg. When the brace was used the effect was obvious and none of the parameters showed any significant differ ence compared to the uninjured leg.

Survival of knee arthroplasties. A nation-wide multicentre investigation of 8000 cases

A prospective nation-wide study of knee arthroplasty has been under way in Sweden since October 1975. By the end of 1983, 4505 arthroplasties for osteoarthritis and 3495 for rheumatoid arthritis had been recorded and reviewed one, three and six years after the operation. Using actuarial methods, the probability of the prosthesis remaining in situ after six years was calculated. In osteoarthritis this probability ranged from 65% for hinged prostheses to 90% for medial compartment prostheses. Two-and three-compartment prostheses produced intermediate results with 87% survival. In rheumatoid arthritis the probability varied from 72% for medial compartment prostheses to 90% for two- and three-compartment prostheses. The main reason for failure was loosening of the components, the second most common was infection. The probability of revision for infection by six years was 2% in osteoarthritis and 3% in rheumatoid arthritis. Most revisions were to a three-compartment prosthesis. Knee fusion at primary revision was required in 2% of the cases at six years.

The Effect of Physiotherapy on Standing Balance in Chronic Anterior Cruciate Ligament Insufficiency

Body sway movements in the frontal plane in a single- limbed stance test were used to assess postural control in 26 patients with chronic anterior cruciate ligament insufficiency. The injured and the noninjured legs were tested before the patients were committed to physio therapy for 3 to 6 months. Follow-up tests were made after 3, 12, and 36 months. Significant disturbance of the balance of both legs was found before training, com pared with a reference group of normal subjects. Values of the noninjured leg were normalized after 3 months of training, but the injured leg still showed an increased body sway. Normal balance parameters on the injured side were found at examination after 12 months. Follow-up examination after 36 months proved persis tent normalization of the single-limbed balance on both sides.

Open-wedge osteotomy by hemicallotasis or the closed-wedge technique for osteoarthritis of the knee: A RANDOMISED STUDY OF 50 OPERATIONS

We describe the results of 50 operations carried out on 46 patients with medial osteoarthritis of the knee of Ahlbäck grade 1 to 3. Patients were randomised either to a closed-wedge high tibial osteotomy (HTO) or an open-wedge procedure based on the hemicallotasis technique (HCO). Their median age was 55 years (38 to 68). The preoperative median hip-knee-ankle (HKA) angle was 171 degrees (164 to 176) in the HTO group and 173 degrees (165 to 179) in the HCO group. After six weeks, the median HKA angle was 185 degrees (176 to 194) in the HTO group and 184 degrees (181 to 188) in the HCO group. In the HTO group, seven patients were within the range of 182 degrees to 186 degrees compared with 21 in the HCO group (p < 0.001). One year later, ten HTO patients were within this range while the HKA angulation in the HCO group was unchanged. At two years the numbers were 11 and 18, respectively. We evaluated the clinical results on the Hospital for Special Surgery, Lysholm and Wallgren-Tegner activity scores, and patients completed part of the Nottingham Health Profile questionnaire. An impartial observer at the two-year follow-up concluded that all scores had improved, but found no clinical differences between the groups.

Proprioception in the nearly extended knee. Measurements of position and movement in healthy individuals and in symptomatic anterior cruciate ligament injured patients

Proprioception of the knee was measured in 19 healthy individuals to evaluate whether there were any differences between extension and flexion movements from two different starting positions. The threshold before detecting a passive movement, visual estimation on a protractor of a passive change in position (30o angular change) and active reproduction of the same angular change were registered. The reference population was tested twice to study normal variation and reproducibility, followed by the evaluation of 20 patients with chronic, symptomatic and unilateral anterior cruciate ligament (ACL)-deficient knees. In the normal population no differences were found between the right and the left leg, men and women, or measurements made at the first and at the second test occasion. The thresholds from a starting position of 20o were lower for extension than for flexion. When comparing the thresholds for extension between the 20o and the 40o starting position, lower values were lower from the 40o starting position. than from the 20o starting position. The active reproduction of an angular change of 30o was more accurate during flexion (30o–60o) than during extension (60o-30o). There were no differences in the reproduction tests or in thresholds from the 40o starting position between the patients and the normal group, but the patients had higher thresholds from the 20o starting position, in movements towards both extension 1.0o (range 0.5o–12.0o) and flexion 1.5o (range 0.5o–10.0o) than the normal group 0.75o (range 0.5o–2.25o) (P=0.01) and 1.0o (range 0.5o–3.0o) (P=0.06), respectively. Thus, information of passive movements in the nearly extended knee position was more sensitive towards extension than towards flexion in threshold tests and the sensitivity improved closer to full extension, which implies a logical joint protective purpose. In this nearly extended knee position, which is the basis for most weight-bearing activities, patients with symptomatic ACL-deficient knees had an impaired awareness in detecting a passive movement. There were no differences in the more flexed position or in the reproduction tests between the patients and the normal group, and reproduction tests in the present form seem less appropriate to use in the evaluation of ACL injuries.

Osteoarthritis of the knee: correlation of subchondral MR signal abnormalities with histopathologic and radiographic features

Subchondral signal abnormalities are often present on magnetic resonance (MR) images of patients with osteoarthritis, but no study correlating these changes with histopathology has been published. We selected nine consecutive patients with clinical and radiographic diagnosis of moderate to severe osteoarthritis of the knee scheduled to undergo joint replacement surgery, and performed MR imaging and conventional radiographs preoperatively. After surgery, the resected portions of the femur and tibia underwent gross and microscopic examination, and the findings were correlated with the corresponding findings on the imaging studies. Subchondral MR signal abnormalities of the femur or tibia were present in seven of the nine patients, with intermediate signal on T1-weighted images and low or isointense signal on T2-weighted images. The subchondral signal abnormalities were hemispherical in configuration and corresponded predominantly to fibrous tissue replacing the fatty marrow. A component of trabecular thickening was also present.

Arthrodesis after failed knee arthroplasty. A nationwide multicenter investigation of 91 cases.

Ninety-one patients with attempted arthrodesis after failed knee arthroplasty were identified in a prospective nationwide study of knee arthroplasties performed from October 1975 through January 1982 in Sweden. The study included 43 hinged or stabilized, 34 bi- or tricompartment, and 14 unicompartment endoprostheses. Three-fourths of the failures were caused by infections. At follow-up evaluation, two patients had expired from infection and four patients had amputations. Fusion was achieved in only 50% of 108 attempts in 91 knees. Patients with unstable joints had limited function. The fusion rate was relatively high after unicompartment endoprostheses, in cases with sustained rigid fixation, or in cases where infection was brought under control at arthrodesis. Rigid fixation was best achieved with an external double frame or an intramedullary nail. Repeated attempts were worthwhile. Removal of all foreign material, eradication of the infectious lesion, and an arthrodesis performed in a one- or two-stage procedure with insertion of gentamicin beads seemed to be the best way to combat infection. The treatment of prosthetic failures should be referred to centers with special interest in knee arthroplasty.

Cartilage regeneration after proximal tibial osteotomy for medial gonarthrosis : An arthroscopic, roentgenographic, and histologic study

High tibial osteotomy for medial gonarthrosis was performed in 28 patients (28 knees). At the time of surgery, arthroscopy was also performed and a cartilage-bone biopsy was obtained. Postoperatively, 15 patients were randomized to a cylinder plaster cast, whereas 13 patients had a hinged cast brace for early knee mobilization. At follow-up examination, two years after surgery, 16 patients accepted an arthroscopic examination with a cartilage-bone biopsy. In overcorrected knees, cartilage regeneration was found in eight of 14 patients on the medial tibial condyle and in nine of 14 on the medial femoral condyle. The main repair feature was proliferation of fibrocartilage, which covered bone and areas of fibrillated cartilage and filled vertical clefts in hyaline cartilage. The hyaline cartilage showed an increased cellularity with numerous nests of proliferating chondrocytes. No correlation was found between clinical outcome and the degree of cartilage regeneration as observed by arthroscopy, biopsy, or roentgenography. Knees with a brace postoperatively had better knee flexion two years after surgery. No difference in cartilage regeneration was recorded between knees with a plaster cast or a cast brace postoperatively.