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At least 235 records · Page 13Linked to original sources
PubMed2005

Superior dislocation of the patella with early onset patellofemoral arthritis: a case report and literature review.

Among the traumatic patellar dislocations, superior dislocation of patella without patellar ligament injury is very rare. We present in this article, a case of superior dislocation of the patella trapped by interlocked osteophytes in a 38-year-old female who had concurrent bilateral knee arthrosis. Successful reduction was achieved by closed manipulation without anesthesia. Neither redislocation nor symptoms of instability was seen after 36 months of follow-up, although some progression of arthritis was observed. A new classification including all traumatic patellar dislocation was also proposed.

Adult↗
PubMed2005

Reconstruction of the medial patellofemoral ligament for patellar instability using a semitendinosus autograft.

Between 1999 and 2001 thirty knees underwent a semitendinosus tendon plasty to recreate the medial patellofemoral ligament for recurrent patellar dislocation. The mean follow-up was 38 months. The mean improvement of the patellofemoral congruence angle after surgery was 14 +/- 7 degrees. All patients ended up with a full range of motion, except one patient, whose flexion was limited to 120 degrees due to superficial wound infections. Dislocation did not recur. According to the Larsen and Lauridsen outcome score the clinical results were excellent in 27 patients, good in 2 and fair in one. In conclusion this procedure is indicated for the chronic dislocation and cases of severe femoral dysplasia with marked laxity. The procedure assures the stabilisation of the patella, although it doesn't restore the patellofemoral congruence angle to normal values.

Adolescent↗
PubMed2000

Bone contusion patterns of the knee at MR imaging: footprint of the mechanism of injury.

Bone marrow contusions are frequently identified at magnetic resonance imaging after an injury to the musculoskeletal system. These osseous injuries may result from a direct blow to the bone, from compressive forces of adjacent bones impacting one another, or from traction forces that occur during an avulsion injury. The distribution of bone marrow edema is like a footprint left behind at injury, providing valuable clues to the associated soft-tissue injuries. Five contusion patterns with associated soft-tissue injuries occur in the knee: pivot shift injury, dashboard injury, hyperextension injury, clip injury, and lateral patellar dislocation. The classic bone marrow edema pattern seen following the pivot shift injury involves the posterolateral tibial plateau and the midportion of the lateral femoral condyle. Edema occurs in the anterior aspect of the proximal tibia following the dashboard injury. Hyperextension results in the "kissing" contusion pattern involving the anterior aspect of the proximal tibia and distal femur. The clip injury results in a prominent area of edema involving the lateral femoral condyle and a smaller area of edema involving the medial femoral condyle. Finally, lateral patellar dislocation results in edema involving the inferomedial patella and anterior aspect of the lateral femoral condyle. In many instances, the mechanism of injury can be determined by studying the distribution of bone marrow edema, which then enables one to predict with accuracy the specific soft-tissue abnormalities that are likely to be present.

Accidents, Traffic↗
PubMed2004

Imaging of patellofemoral disorders.

Anterior knee pain is a common symptom, which may have a large variety of causes including patellofemoral pathologies. Patellofemoral maltracking refers to dynamic abnormality of patellofemoral alignment and has been measured using plain film, computed tomography (CT) and magnetic resonance imaging (MRI) using static and kinematic techniques. Patellar dislocation is usually transient, but specific conventional radiographic and MRI features may provide evidence of prior acute or chronic dislocation. In addition, chondromalacia patellae, osteochondritis dissecans, patellofemoral osteoarthritis, excessive lateral pressure syndrome, and bipartite patella have all been implicated in causing patellofemoral pain. The imaging and clinical features of these processes are reviewed, highlighting the specific diagnostic features of each condition.

Arthroscopy↗
PubMed2003

A modified test for patellar instability: the biomechanical basis.

OBJECTIVE: (1) Determine if displacement of the patella in a distal lateral direction results in a more sensitive method to show deficiency of the medial patellofemoral ligament (MPFL), the primary restraint to lateral patellar dislocation, than the traditional patellar apprehension test in a direct lateral direction. (2) Determine objective criteria for defining a positive patellar instability test rather than subjective evaluation of apprehension. DESIGN: In vitro biomechanical study. SPECIMENS: Ten above-the-knee amputation specimens. MAIN OUTCOME MEASURES: Force-displacement curves with direct lateral patellar displacement were compared with curves with distal lateral patellar displacement before and after sectioning the MPFL. RESULTS: After dividing the MPFL, average terminal restraining force to distal lateral patellar displacement declined by 53% (P=0.024), but force declined only by 30% (P=0.09) with lateral displacement. The greatest difference in terminal slope (eg, end point) was with the MPFL intact with lateral displacement compared with distal lateral displacement with the ligament divided (P=8.67x10(-5)). The terminal slope declined after ligament division with lateral (P=0.07) and distal lateral patellar displacement (P=0.09). CONCLUSION: Displacement of the patella in a distal lateral direction is a more sensitive maneuver to detect disruption of the MPFL, the primary soft tissue restraint, than with traditional lateral displacement. With the knee flexed 30 degrees and patella displaced 2 cm, objective criteria for a positive patellar instability test include greater ease of patellar translation and a softer end point compared with a normal, contralateral knee.

Adult↗
PubMed1995

Mathematical determination of the tibial insertion of the patellar tendon using computed tomography images.

Misalignment of the extensor apparatus is an essential factor in impairment of the patellar-femoral joint. This may be partly or entirely responsible for patellar dislocation or lateral patellar-femoral arthrosis. One surgical method to correct the pathology is medial transposition of the patellar ligament on the tibial tuberosity (anteriorly or posteriorly, distally or ventrally). These interventions correct misalignment of the extensor apparatus relative to statistical norms. We propose a mathematical method based on the use of computed tomography (CT) images to determine the ideal tibial insertion for the patellar tendon. This method is based on biomechanical modeling and the use of equipressure criteria. It is the first step in allowing the use of mathematics to model correctly tibial insertion of the patellar ligament, an entirely new development. This is important because it will allow surgeons greater accuracy in distal correction of extensor apparatus misalignments.

Biomechanical Phenomena↗
PubMed2003

The use of stereolithography for an unusual patellofemoral disorder.

A patient with habitual patellar dislocation which was not treated successfully by the Elmslie-Trillat procedure is described. In the knee, a unique morphologic feature of the patellofemoral joint was suspected as a cause, and a stereolithographic model was produced from the patient's computed tomography data to determine the pathologic features. Because the solid model confirmed the speculation, additional surgery was done to modify the geometry of the joint. In the surgery, cancellous bone was removed below the cartilage, and the geometry of the cartilage was modified with the subchondral bone, taking advantage of the elasticity of the bone and cartilage. The second surgery eliminated maltracking of the patella and a satisfactory result was obtained. Therefore, stereolithography is useful for the treatment of atypical patellofemoral disorders, allowing an understanding of the pathologic features and dynamic simulation of the surgery. The surgical procedure could be a promising method to alter the joint geometry without impairing the cartilage.

Adult↗
PubMed2002

Patellar tendon length--the factor in patellar instability?

Patellar tendon length has been compared in 42 knees with a history of patellar dislocation, and 51 control knees. A lateral X-ray and a magnetic resonance image (MRI) were taken of each knee. The mean radiological patellar tendon length was 46 mm in the controls and 53 mm in the dislocation group. From MRI images, the mean was 44 mm in controls and 52 mm in the dislocation group. This means that the patellar tendon is significantly (P<0.0001) longer in patients with a history of patellar dislocation on both MRI and X-ray. There is no significant difference (P=0.52) between X-ray and MRI measurements of tendon length. The distance between the tibial plateau and the point of tendon insertion was also measured and found to be 28 and 29 mm in the control and dislocation groups, respectively. There is no significant difference between these two measures (P=0.19). In conclusion, patella alta is caused by a long patellar tendon rather than a low insertion into the tibia. Measuring the length of the patellar tendon using MRI is more specific and more sensitive than the Caton-Deschamps index for patellar instability.

Adolescent↗
PubMed1976

Congenital dislocation of the patella.

In 8 congenital patellar dislocations, in 7 patients, the patella was permanently and laterally dislocated, and irreducible or difficult to reduce. The patella usually was hypoplastic and showed absent facets. The intercondylar groove of the femur also was underdeveloped. In all but one patient, knee function was improved by a surgical procudure which involved lateral release of ptella, medial transpositon of patellar tendon, and plication of medial capsule or advancement of vastus medialis.

Cartilage, Articular↗
PubMedDate not supplied

Patellar pain and quadriceps rehabilitation. An EMG study.

Eighteen patients (26 knees) giving a history of patellar dislocation and/or subluxation and continued patellar symptoms underwent evaluation to determine the efficacy of their rehabilitation programs. Four-channel cine-electromyography was utilized to assess the relative muscular effort of the vastus medialis, vastus lateralis, vastus medialis obliquus, and rectus femoris in a series of exercises. Ten degrees of flexion of the knee reduced effective muscle effort in the vasti group to an average of 1/4 of the muscle effort demonstrated in full extension of the knee. No consistent pattern was noted by altering the rotation of the hip from neutral to external or internal rotation. The addition of weight (5 lb) to the ankle did not enhance the muscle effort with the knee in full extension. Quadsets and straight leg-raising exercises in full knee extension offer the best quadriceps rehabilitation program in the patient with a patellar malalignment syndrome and persistent symptoms.

Adolescent↗
PubMed1985

Nontraumatic superior dislocation of the patella.

A case of superior patellar dislocation is described. The dislocation was sustained without apparent trauma. Closed reduction was accomplished in the emergency department. No apparent injury to the patellar ligament was sustained.

Humans↗
PubMed2006

MRI of osteochondral defects of the lateral femoral condyle: incidence and pattern of injury after transient lateral dislocation of the patella.

OBJECTIVE: The typical bone bruise pattern involving the anterolateral femoral condyle and inferomedial patella after transient lateral dislocation of the patella is a well-described MRI finding. In our study, however, we sought to determine the incidence and location of lateral femoral condyle osteochondral injuries after transient lateral dislocation of the patella. CONCLUSION: Osteochondral defects of the lateral femoral condyle are a common sequela after transient lateral patellar dislocation. A significant number of osteochondral injuries involve the midlateral weight-bearing portion of the lateral femoral condyle and are more posterior than would be expected after transient dislocation of the patella.

Adolescent↗
PubMed1993

Ultrasonographic evaluation of patellar tracking in children.

Patellar positions with the knee in extension and in 10 degrees and 20 degrees flexion were measured by ultrasonography in both knees of 20 children with patellar dislocation and in both knees of 30 healthy children for controls. Ultrasonography proved to be applicable to measuring the distance between the most anterior point of lateral femoral condyle and patellar apex, the sulcus angle and the vertical position of the patella. Compared with normal knees, the sulcus angle was wider and the patellar position more lateral and cranial in both the dislocated and asymptomatic knees of the patients. These results suggest that false tracking of the patella in early flexion is a predisposing factor to patellar dislocation.

Adolescent↗
PubMed2005

[Patellar position and lateral approach for total knee arthroplasty in degenerative knees with lateral femoropatellar arthrosis].

PURPOSE OF THE STUDY: Patellar malposition is a well-recognized patellar complication after total knee arthroplasty. Such residual malposition is particularly frequent when the knee presents lateral femoropatellar arthrosis. We compared the radiological position of the patella after total knee arthroplasty in degenerative knees with lateral femoropatellar arthrosis performed via a medial or lateral approach with elevation of the anterior tibial tuberosity. MATERIAL AND METHODS: Twenty-six total knee arthroplasties were reviewed retrospectively. Thirteen prostheses had been inserted via a medial approach and thirteen via a lateral approach. A posterior stabilized implant was used with an original technique for insertion of the patellar implant. The only difference between the groups was the approach. In the "lateral" group, the lateral approach was used to raise the tibial tuberosity and perform lateral marginal patellectomy. The tibial tuberosity was reinserted in all cases without transposition. Preoperative and 3-month postoperative radiographs (weight-bearing, AP, lateral, femoropatellar 30 degrees flexion) were reviewed. Preoperative patellar displacement was at least 5 mm. There was no difference between the two groups for age, gender, weight, height, joint motion, pre- and postoperative mechanical alignment (HKA), or preoperative patellar gliding (7.6 mm in the "medial" group and 9.7 mm in the "lateral" group). RESULTS: Recurrent patellar dislocation occurred in one patient in the "medial" group and one patient in the "lateral" group had an anterior impaction of the tibial plateau following a fall. Patellar gliding was corrected in both groups: 0.7 +/- 1.8 mm in the "medial group" and 0.0 +/- 0 in the lateral group (p > 0.05). Residual patellar tilt was +4.2 +/- 3 degrees in the medial group (lateral tilt) and -3.3 +/- 5.4 degrees in the lateral group (medial tilt) (p = 0.003). DISCUSSION: Pateller gliding was corrected irrespective of the approach. Conversely, the medial approach did not allow effective correction of patellar tilt. The lateral approach with elevation of the anterior tibial tuberosity did not increase morbidity compared with the medial approach. It enabled avoiding residual lateral patellar tilt which can be a source of patellar complications. We prefer this approach for arthroplasty on degenerated knees with lateral femoropatellar arthrosis.

Aged↗
PubMed2000

[Surgical treatment of recurrent dislocation of the patella in children].

OBJECTIVE: To study an operative method for repair of recurrent dislocation of the patella in children. METHODS: 36 children with recurrent patellar dislocation were treated surgically at an average age of 9.1 years. They were followed on average for 4 years and 4 months. Nine of the 36 children underwent bilateral repair, with 45 knees were treated. The combined soft tissue operations included lateral retinacular releasing, medial retinacular tightening of the knee, vastus medialis muscle transfer to the patella, medial and distal transfer of the half patellar tendon. RESULTS: 28 patients had stable knee joint and a full range of motion, and improved sports activity after operation. Seven children achieved satisfactory function of the knee joint but there was no significant difference between pre-and postoperative sports exercise ability. One child suffered from a redislocation of the patella. Wound infection was not seen and the range of knee joint motion was not restricted in all patients. CONCLUSIONS: The combined procedures for repair of recurrent dislocation of the patella in children risk free for growth disturbances secondary to iatrogenic injury to the proximal tibial physis. It is safe and effective for recurrent dislocation of the patella in skeletally immature children.

Adolescent↗
PubMed1992

Posterior dislocation of total knee arthroplasty.

Posterior dislocation of the prosthesis after total knee arthroplasty is an infrequent but serious complication. Seven patients with this complication were treated from January 1985 until October 1989. Five of the seven dislocations occurred in primary total knee arthroplasties and two occurred after revision arthroplasty. Limb alignment before arthroplasty, when it could be determined, was valgus in all patients, averaging 25 degrees. In each case there was an identifiable problem with the knee extensor mechanism: five had patellar dislocations, one a patellar tendon rupture, and one a patellar fracture. In three of the posterior dislocations, there was also an imbalance of the flexion and extension gaps with excessive laxity of the ligaments in flexion. Treatment was individualized. In two patients, the knee was reduced closed and the patella subsequently tracked so that no reoperation was necessary. One ruptured patellar tendon could not be repaired in a 94-year-old patient with cardiac disease. A cylinder cast was applied with poor results. Operative intervention was required in four patients, one of whom required only a patellar realignment procedure. The three other patients required component revision procedures, however, in addition to patellar realignment procedures. In these three patients, laxity of the knee in flexion was so severe that posterior instability could not be corrected merely by patellar relocation. At a follow-up examination (average, 21 months postoperatively), all six patients who were treated as recommended had good results with no further dislocations, with the exception of the one patient with a patellar tendon rupture.

Aged↗
PubMed1993

Scoring of patellofemoral disorders.

A new questionnaire was used to evaluate subjective symptoms and functional limitations in patellofemoral disorders. The questionnaire was completed independently by four groups of female subjects: controls (N = 17), and subjects with anterior knee pain (N = 16), patellar subluxation (N = 16), and patellar dislocation (N = 19). The questionnaire mean scores for the groups were 100, 83, 68, and 62 points, respectively (p < 0.0001). The items dealing with abnormal painful patellar movements (subluxations) (p < 0.0001), limp (p < 0.0001), pain (p < 0.0001), running (p < 0.0001), climbing stairs (p < 0.0001), and prolonged sitting with the knees flexed (p < 0.0001) differentiated the study groups most clearly. We recommend that these questions be asked when taking a standardized clinical history of an anterior knee pain patient. We also analyzed lateral patellar tilt and displacement by magnetic resonance imaging (MRI) in 28 subjects with patellar subluxation or dislocation. Low questionnaire sum score correlated best with increased lateral patellar tilt measured during quadriceps contraction in 0 degree knee flexion. It seems that a tendency to lateral patellar tilt during quadriceps contraction causes anterior knee pain and can be imaged in knee extension when the patella is not fully supported by femoral condyles.

Cartilage Diseases↗
PubMed2003

Reconstruction of the medial patellofemoral ligament for the treatment of habitual or recurrent dislocation of the patella in children.

We investigated the clinical outcome of a reconstructive procedure of the medial patellofemoral ligament for the treatment of habitual or recurrent dislocation of the patella in four children (6 knees), with a minimum follow-up of four years. The technique involves transfer of the tendon of semitendinosus to the patella using the posterior one-third of the femoral insertion of the medial collateral ligament as a pulley. There was no recurrence of dislocation after surgery. The mean Kujala score at follow-up was 96.3 points. Radiological assessment showed that the congruence angle, the tilt angle and the lateral shift radio were restored to normal. The lateral and medial stress shift ratios and the Insall-Salvati ratio remained abnormal. We conclude that this technique can be recommended for the treatment of habitual or recurrent patellar dislocation in children, although hypermobility and patella alta are not fully corrected.

Child↗