The Blackburne and Peel method of assessing the position of the patella was applied to 185 knees with Osgood--Schlatter disease in 125 patients. The normal index of 0.80 was confirmed in 73 control knees. The average index in the knees with Osgood--Schlatter disease measured 1.01 (patella alta) boys and 0.91 in girls. The value increased to 1.06 in boys with radiological evidence of loose ossicles in the tibial tuberosity or the patellar tendon. This finding indicates that the strong pull of the well-developed quadriceps muscle is probably the most important aetiological factor in patella alta associated with Osgood--Schlatter disease

Removal of a small, moderate or major part of the articular cartilage of the patella for chondromalacia has been successful in twenty-two knees out of twenty-eight. These knees are functionally at least as good as after a successful patellectomy, and their appearance is better. Only one knee that was initially improved by operation deteriorated during a follow-up period of five to seven years. Of the six unsuccessful results, four were in patients whose symptoms began during adolescence. Excision of articular cartilage therefore seems to be contra-indicated during adolescence and when there is reason to believe that the chondromalacia will be rapidly progressive. Failure of excision of articular cartilage to relieve the symptoms within a few months is an indication for patellectomy

A case of intra-articular dislocation of the patella is reported. Its special interest lies in the apparent simplicity of both injury and reduction

Case histories are given of three patients, two of whom had stress fractures of the patella, and one had a similar condition due to stress

We report a prospective study of 55 patients with acute primary patellar dislocation, all treated by operation and followed up for at least two years. Diagnosis was based on the history of a lateral displacement, with medial tenderness and a positive apprehension test; redislocations were excluded. Before operation, the difference in lateral shift on skyline views of the injured and control patellae was highly significant. At operation, rupture of the medial retinaculum of the patella was seen in all but one case. There were medial marginal fractures of the patella in 23 cases. Subjective results of the operation were excellent or good in 44 of the 55 at two years with a redislocation rate of only 9%. Most patients were able to return to the same level of sporting activity as before the injury

1. A case of primary osteosarcoma of the patella is reported. 2. A brief review of the literature has been made. 3. In the author's opinion only nine genuine cases have been reported, including the present case

Resection arthroplasty of the patella has been found to be a satisfactory procedure for the treatment of patellofemoral pain caused by osteoarthritis. In the present series 60% of the operated cases were pain-free on a 31-month average follow-up. The patients found it easier to climb stairs and to kneel and in most cases the radiographic joint space was good

We present a case of superior dislocation of the patella trapped by interlocked osteophytes. Unlike previous reports, in which the mechanism resulted from a blow to the inferior pole, it is postulated that increased load on the extensor mechanism, combined with patella alta and patellofemoral osteophytes, caused locking of the knee in extension

1. A study has been made of the treatment of recurrent dislocation of the patella in 106 knees in seventy-six patients. 2. In young adults in whom degenerative changes in the knee were not severe at the time of operation transplant of the tibial tubercle gave the best results. 3. In older patients and in those in whom osteoarthritic changes were present in the knee transplant of the tibial tubercle was unsatisfactory, but patellectomy with rerouting of the quadriceps mechanism gave fair results. 4. Tibial tubercle transplant is contra-indicated in children because it may give a recurvatum deformity. 5. When the dislocation is permanent, operation may be unnecessary, but if it becomes inevitable simple patellectomy is the best procedure. 6. The results of plastic operations on the quadriceps expansion and of supracondylar femoral osteotomy are bad. 7. No operation can give consistently good results because the knee is usually congenitally weak, often as part of generalised ligamentous laxity

Patellectomy is at present the best operation for recurrent dislocation, not only because the immediate result is excellent, but because it avoids the later arthritis which must inevitably arise if a patella so damaged is retained

1. Four cases of congenital lateral dislocation of the patella are described. 2. The significance of the associated flexion contracture is emphasised. 3. Early diagnosis and operative realignment of the extensor mechanism is considered to be important because it should avoid the secondary growth changes which can produce serious disability

The Unified Classification System (UCS) was introduced because of a growing need to have a standardised universal classification system of periprosthetic fractures. It combines and simplifies many existing classification systems, and can be applied to any fracture around any partial or total joint replacement occurring during or after operation. Our goal was to assess the inter- and intra-observer reliability of the UCS in association with knee replacement when classifying fractures affecting one or more of the femur, tibia or patella. We used an international panel of ten orthopaedic surgeons with subspecialty fellowship training and expertise in adult hip and knee reconstruction (‘experts’) and ten residents of orthopaedic surgery in the last two years of training (‘pre-experts’). They each received 15 radiographs for evaluation. After six weeks they evaluated the same radiographs again but in a different order. . The reliability was assessed using the Kappa and weighted Kappa values. The Kappa values for inter-observer reliability for the experts and the pre-experts were 0.741 (95% confidence interval (CI) 0.707 to 0.774) and 0.765 (95% CI 0.733 to 0.797), respectively. The weighted Kappa values for intra-observer reliability for the experts and pre-experts were 0.898 (95% CI 0.846 to 0.950) and 0.878 (95% CI 0.815 to 0.942) respectively. The UCS has substantial inter-observer reliability and ‘near perfect’ intra-observer reliability when used for periprosthetic fractures in association with knee replacement in the hands of experienced and inexperienced users. Cite this article: Bone Joint J 2014;96-B:1669–73

Thirty-five patients with habitual dislocation of the patella in flexion were reviewed; eight were bilaterally affected. Each had undergone quadricepsplasty with an average follow-up of 6 years 9 months. Bands or contractures, most commonly in vastus lateralis, the iliotibial tract and rectus femoris were seen in each. Redislocation was seen in 12 knees. At review, 79% of the knees were normal. Quadriceps lengthening is an essential part of treatment and must be performed proximally. Causes for failure include reformation of contractures and failure to correct the initial abnormality fully

The role of muscle function in the aetiology of recurrent dislocation of the patella has been examined. Eleven of the 12 patients we studied had joint hypermobility. Muscle biopsies from eight of nine patients treated by surgery had a predominance of abnormal Type 2C fibres, and three of six patients whose quadriceps muscles were studied by electromyography also had abnormal results. Our preliminary findings suggest that there may be a primary muscular defect in many cases of recurrent dislocation of the patella

Six boys with fragmentation of the proximal pole of the patella are reported; the condition was bilateral in one. Four of the six presented with symptoms of Osgood-Schlatter's disease or Larsen-Johansson disease of the same or of the contralateral knee, but they had no symptoms or signs relating to the proximal pole of the patella; one also had features suggesting minimal chondromalacia patellae. Two boys had no objective abnormality in either knee. It is suggested that the fragmentation may be a further form of traction osteochondritis of the attachments of the quadriceps mechanism. Attention is drawn to its characteristic radiographic appearance, its association with other forms of juvenile traction osteochondritis (which are commonly symptomatic), and to its occurrence in boys aged 10 or 11 years

Mechanical derangements of the knee are an uncommon complication of chronic haemophiliac arthropathy. Two patients with locking of the patella were treated by manipulation. The mechanism of the injury was forced flexion of the knee joint beyond the limit of its restricted range. The injury is a serious one and may take six months to recover

1. Semitendinosus tenodesis with adequate lateral release for recurrent dislocation of the patella has a high success rate and a low complication rate. 2. The technique of operation is simple. 3. Its particular application is in the young patient before epiphysial closure, although it can give good results in the older patient

From 1970 to 1978, 29 patients had a unilateral operation for bilateral recurrent dislocation of the patella. We examined 21 of them at a mean of 14 years postoperatively. Eighteen of these patients had evidence of generalised joint laxity. Six of the operated knees and four of the unoperated knees still had recurrent dislocations. The operated knees were clinically worse, with a significantly higher incidence of osteoarthritis. We concluded that the operations used to treat recurrent dislocation of the patella may have had short-term benefits, but did not cure the patients in the long term

In a group of 25 patients with traumatic dislocation of the knee, four, all of whom had similar ligament and medial soft-tissue injuries, also had associated lateral patellar dislocation. In all four reconstruction was delayed because of their other serious injuries. Having encountered the combination of knee dislocation and lateral patellar dislocation in 16% of our patients, we believe that it may be less rare than is commonly believed. We think that it is important to maintain a high index of suspicion of possible patellar dislocation when medial structures have been severely damaged. Early recognition and immobilisation in extension can prevent fixed lateral dislocation of the patella