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PubMed1988

Lateral release and proximal realignment for patellar subluxation and dislocation. A long-term follow-up.

Fifty-two patients (sixty knees) who had a diagnosis of either patellar subluxation or dislocation had an operation consisting of a lateral release and proximal realignment of the patella. The duration of follow-up ranged from two to nine years. At the latest follow-up, forty-two (80.8 per cent) of the patients had a good or an excellent clinical result; only one patient had redislocation of the patella. The results were not affected by the grade of chondromalacia that was present at the time of operation; however, the differences in the results as correlated with the age and sex of the patient were statistically significant, the older patients having poorer results and the male patients, better results. Roentgenographic analysis of the postoperative position of the patella, as seen on the view described by Merchant et al., revealed that centralizing the patella in the intercondylar sulcus yielded the most favorable results.

Adolescent↗
PubMed1996

Patellofemoral complications following total knee arthroplasty. Effect of a lateral release and sacrifice of the superior lateral geniculate artery.

Between 1987 and 1989, 1,205 Anatomic Graduated Component (AGC, Biomet, Warsaw, IN) total knee arthroplasties were performed by three surgeons using the same prosthesis and same technique. Four hundred twenty-eight total knee arthroplasties (35%) had lateral releases; in 107 (75%) of these, the superior lateral geniculate artery was saved. Lateral release had no effect on patellar subluxation, dislocation, or loosening, but was associated with significantly more patellar fractures. Conversely, patellar radiolucency was more common in knees without a lateral release. Furthermore, saving the superior lateral geniculate artery during a lateral release had no effect on patellar dislocation, radiolucency, loosening, or fracture.

Aged↗
PubMed1983

The dislocating patella. Etiology and prognosis in relation to generalized joint laxity and anatomy of the patellar articulation.

The material of this investigation consisted of 104 patients (37 males and 67 females), treated for dislocation of the patella at the Department of Orthopedics in Lund during 1975-1977. The patients were examined clinically and radiographically in order to identify the etiologic importance of trauma, generalized joint laxity, and an anatomically abnormal patellar articulation. All patients were examined for generalized laxity, other orthopedic conditions, relatives with patellar dislocation or congenital dislocation of the hip, dislocation frequency, bilateral patellar dislocation, age and the nature of the trauma at initial dislocation, incidence and type of articular fractures associated with patellar dislocation, and three radiographic parametres of anatomically abnormal patellar articulations. Generalized joint laxity was observed in two thirds of the patients, frequent dislocations in one half and bilateral dislocations in one third. In half of the patients the initiating trauma was insignificant, and one third had avulsion or osteochondral fractures. The majority had definite anatomic abnormalities but patella alta was observed in only one fourth of the patients. The material was subjected to an analysis of the covariation of etiologic factors operating in patellar dislocation. On this basis the material was classified in four grades of increasing patellar instability, from Grade I with neither laxity, nor increased Insall index, to Grade IV with both these factors. With increasing patellar instability the frequency of recurrent and bilateral dislocations increased whereas the degree of trauma and incidence of fractures decreased. The type and degree of anatomic abnormalities were correlated to the different grades of patellar instability. The classification of patellar instability proposed here should permit more precise evaluation of treatment of patellar instability, and, eventually, provide a basis for the choice of therapy in patellar dislocation.

Adolescent↗
PubMed1993

The effect of femoral component position on the kinematics of total knee arthroplasty.

In a laboratory study using seven fresh-frozen anatomic specimen knees, the effect of total knee arthroplasty on the three-dimensional kinematics of the patella, femur, and tibia were measured. Experiments were performed in the intact knee, after division of the anterior cruciate ligament (ACL), after total knee arthroplasty, and after 10 degrees internal rotation, 10 degrees external rotation, 5-mm medial shift, and 5-mm lateral shift of the femoral component on the femur. The presence of a high lateral ridge on the anterior surface of the femoral component effectively prevented patellar subluxation or dislocation, but displaced and tilted the patella medially. Internal rotation or medial displacement of the femoral component exaggerated this medial patellar displacement and shift. External rotation of the femoral component corrected it, except at flexion angles greater than 100 degrees, where the femur was shifted medially on the tibia and externally rotated 15 degrees. This combination produced a net 10-mm medial displacement of the patella relative to the tibia at 120 degrees knee flexion. Lateral placement of the femoral component compensated for the effect of the high lateral ridge and allowed more normal patellar tracking while allowing tibiofemoral motions similar to those seen after sectioning of the ACL. The kinematics of the patellofemoral and tibiofemoral joints were not reproduced with a total knee prosthesis that sacrifices the ACL. When using a prosthesis with a high lateral ridge, lateral placement of a femoral component prevented patellar dislocation and allowed patellar tracking patterns similar to those seen in the intact knee without further altering tibiofemoral motions.

Adult↗
PubMed1999

[Knee dislocation treatment with temporary tibio-patellar fixation (patellar olecranization)].

Four patients with traumatic dislocation of the knee has been treated with olecranization of the patella. Mean age was 44.4 years (range 27-75 years). Three of them were politrauma patients, but none had popliteal artery injury or peroneal nerve palsy. Olecranization of the patella was performed on the day of injury. Results were assessed according to the Marshall scale. Three results were rated excellent and good with near normal knee function. In one case result was rated fair since despite stable knee and full range of motion pain persisted and marked vascular changes, not related to the injury were present.

Adult↗
PubMed2006

Bilateral dislocation of the knee with rupture of both patellar tendons. A case report.

Knee dislocations are rare injuries caused by violent trauma. Damage to soft tissues and ligament lesions almost always accompany the injury. Vascular compromise further complicates the situation. We report a case of bilateral posterior knee dislocation with traumatic rupture of both patellar tendons. Treatment consisted of external fixation of both knees. Vascular compromise resolved with reduction and traction pins were placed on both patellae which were connected to the external fixators on following days. Primary repair of patellar tendon was undertaken after gradual distal repositioning of patella. The result is successful with full range of motion. Rupture of patellar tendon should be considered with posterior dislocation of the knee. External fixators provide quick stabilization in case of vascular compromise and can be modified to provide a traction system for distal repositioning of patella which allows primary repair of the patellar tendon.

Accidents, Traffic↗
PubMed1988

Patellar instability with recurrent dislocation due to patellofemoral dysplasia. Results after surgical treatment.

Twenty-one patients (25 knees) with recurrent dislocation of the patella due to patellofemoral dysplasia were treated with a combined distal and proximal realignment of the extensor mechanism of the knee. In addition to traditional medial transfer of the tibial tuberosity, lateral release, and medial joint capsule duplication, vastus medialis transposition and deepening of the intercondylar sulcus on the proximal joint surface of the femur were done. A follow-up ranging from 1-14 years (mean 6 years) found the results excellent or good in 22 knees, fair or poor in three. One redislocation occurred after trauma. There were two minor complications which had no effect on the end result. The use of computerized tomography over the patellofemoral joint to assess patellar subluxation and patellofemoral dysplasia is an important part of the diagnostic preoperative evaluation.

Adult↗
PubMed2005

A new technique for reconstructing the medial patellofemoral ligament.

Many surgical techniques exist for treating patella instability. Over recent years, attention has focussed on reconstruction of the medial patellofemoral ligament (MPFL). We report a procedure involving a lateral release, distal realignment of the tibial tubercle and anatomic reconstruction of the MPFL using a graft composed of a redundant strip of medial retinacular tissue. Nineteen patients (twenty-one knees) with chronic patellofemoral instability who had failed conservative treatment underwent this procedure and were assessed clinically and radiologically at an average of 23 months post-operation. No patients were lost to follow-up. There was no recurrence of subluxation or dislocation. All achieved levels of activity comparable to or improved compared to pre-operative uninjured levels. This combined procedure incorporating a previously un-described method of reconstructing the MPFL gives superior results compared to previous studies. No graft donor site morbidity occurred and patient outcome scores, especially objective stability of the patella to lateral shift, were excellent.

Humans↗
PubMedDate not supplied

Congenital dislocation of the patella. Part I: pathologic anatomy.

There has been considerable confusion between true congenital dislocation of the patella and other patellar instabilities. Only very few papers describing the anatomical features of congenital dislocation of the patella are found in the literature. The purpose of this paper was to describe the anatomical anomalies found in two cadaver specimens of a true permanent and irreducible congenital patellar dislocation. The quadriceps femoris is short and displaced laterally and acts as a knee flexor. The patella is small, articulating with the outer aspect of the lateral condyle, with no possibility of medial reduction onto the trochlea. Many other anomalies involving the bones, muscles, and nervous structures were found. Congenital dislocation of the patella must be distinguished from other patellar dislocations in children. The severity of structural anomalies is mainly owing to its prenatal onset. Congenital

Abnormalities, Multiple↗
PubMed2003

The anatomy and reconstruction of the medial patellofemoral ligament.

INTRODUCTION: Reconstruction of the MPFL for recurrent and acute lateral dislocation of the patella is becoming more accepted. This study aimed to further define the medial patellofemoral ligament (MPFL) anatomy and to describe the most suitable sites for graft attachment when reconstructing the MPFL. MATERIALS AND METHODS: Anatomical dissection was performed on 25 embalmed knee specimens. Four separate specimens were used to assess graft fixation points. Sites were tested for isometricity from 0 to 120 degrees of knee flexion. Length patterns were considered isometric if there was less than 5 mm of length change throughout range of motion. RESULTS: The MPFL attaches from the posterior part of the medial epicondyle, to the superomedial patella, the under-surface of vastus medialis, and the quadriceps tendon. Optimal attachment points for an MPFL graft were the superior patella and the femoral attachment points of the MPFL (just distal to the adductor tubercle) and points posterior and inferior to this. CONCLUSION: We have defined the anatomy and kinematics of the MPFL with reconstruction of this ligament in mind.

Arthroplasty, Replacement, Knee↗
PubMed1980

Treatment of the patellar syndrome in non dislocated patellae.

Forty patients who had previously been treated in a conservative way, were operated. The surgery involved the section of the external lateral patella expansion. When reviewing the patients the following criteria were taken into considerations: subjective symptomatology, clinical and radiological examinations as well as the time factor in taking up work again. The results after operation were as follows: 87% good or excellent and 13% mediocre.

Adolescent↗
PubMed2006

Correcting lateral patellar tilt at the time of total knee arthroplasty can result in overuse of lateral release.

Ninety-nine patients undergoing primary total knee arthroplasty were prospectively evaluated for pre-resurfacing and post-resurfacing patellar thickness and medial patellar liftoff at 30 degrees of flexion without manual pressure on the patella. Regardless of medial patellar liftoff, no lateral releases were performed. Tibiofemoral angles, patellar tilt, and patellar congruence angles were measured preoperatively and postoperatively. There were no patellar subluxations, dislocations, or complications related to the patellofemoral joint. Patellar tilt improved from 7.9 degrees preoperatively to 3.8 degrees postoperatively. Patients with 10 mm or more of intraoperative liftoff improved from 9.9 degrees tilt preoperatively to 6.6 degrees postoperatively. Patients with no intraoperative liftoff had a change from 6.3 degrees to 2.9 degrees . Although the 2 groups were statistically different, the amount of change in alignment was not different between the groups. Patients with medial patellar liftoff at the time of arthroplasty do not appear to require lateral release to yield acceptable postoperative patellofemoral alignment.

Aged↗