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Biomedical subjects

D Dejour

Publications and source records attributed to D Dejour.

10 recordsLinked to original sources

Bony and cartilaginous anatomy of the patellofemoral joint.

The patella as the largest sesamoid bone of the human body forms the patellofemoral joint with the patellar groove of the femur. The patellofemoral joint is a complex articulation with high functional and biomechanical requirements. Several anatomical variants of both patella and the trochlea exist. Multiple clinical problems of the knee may be caused by anatomical and physiological abnormalities of this joint. Exact knowledge about the anatomy, the biomechanics and the function of the patellofemoral joint is therefore required to understand its wide range of pathology.

Bone Diseases, Developmental↗

[Not Available].

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Journal Article↗

[Knee para-articular flexion and extension osteotomies in adults].

The present review analyzes the rare indications for sagittal knee osteotomies either for some complex cases of capsular and ligamentous laxities in combination with or without bony deformities in the sagittal plane. A thorough clinical and radiological analysis of the patients' knees is mandatory. We routinely recommend lateral standing X-rays to assess not only the bony structures, but also an abnormal knee laxity in the sagittal plane. We present different surgical options and preliminary results of these technically demanding procedures.

Bone Malalignment↗

[Knee imaging: what is the best modality].

A wide range of exams are available for imaging the knee: standard radiography, ultrasound, bone scintigraphy, CT scan, arthroscan, MRI, arthro-MRI. The radiologist must be aware of the performance capacities of each technique in order to orient the clinician's choice towards the most appropriate exam in a given clinical situation. In the first part of this paper, we examine the performances, advantages and disadvantages of each technique: exam conditions (patient position, incidence, slice thickness, sequence.) are detailed as required. The second part is a practical guide for some typical clinical situations with decision trees for ordering necessary and sufficient explorations.

Algorithms↗

Patellar instability: assessment on MR images by measuring the lateral trochlear inclination-initial experience.

Lateral trochlear inclination (LTI) of the knee was compared on magnetic resonance (MR) images obtained in 30 patients with patellar instability (PI) and 30 patients with nonspecific internal knee derangement. Differences in LTI values between the two populations were significant (P <.001). Reproducibility of the measurement was judged excellent with an intraclass correlation superior to 0.98. Below a threshold value fixed at 11 degrees, LTI appears to be an excellent diagnostic test of PI with a sensitivity of 0.93 (28/30), a specificity of 0.87 (26/30), and an accuracy of 0.90 (54/60).

Adolescent↗

Laxity in posterior cruciate sparing and posterior stabilized total knee prostheses.

Two series of consecutive total knee replacements were compared retrospectively: 118 HLS II posterior stabilized prostheses (Group 1) versus 138 HLS CP posterior cruciate ligament sparing prostheses (Group 2). Both implants were made by the same manufacturer. The prostheses had been inserted between 1989 and 1992. Mean followup was 4 years. The authors looked for evidence of laxity in the coronal and the sagittal planes, the correlation of laxity with other factors, and the effect of laxity on the objective and subjective outcome as measured with the Knee Society score. Group 2 had significantly more clinical and radiologic laxity. There was little difference between the two groups regarding the overall objective and subjective outcome; however, there was a significantly higher rate of excellent results in Group 1. Longer followup will be required to see whether the implants with laxity are at heightened risk for tibial component wear.

Adult↗

[Chronic anterior laxity of the knee treated with free patellar graft and extra-articular lateral plasty: 10-year follow-up of 148 cases].

PURPOSE OF THE STUDY: Assess long-term subjective, functional and radiographic outcome after free patellar graft and extra-articular lateral plasty for chronic anterior laxity of the knee. PATIENTS AND METHODS: 148 cases of chronic anterior laxity of the knee treated by free patellar graft and extra-articular lateral Lemaire plasy were reviewed after a mean follow-up of 11.5 years (range 10-15 years). A complete work-up was performed in all cases at 4 years postsurgery to assess objective, sport, function and radiographic outcome (objective laxity and osteoarthritic status). RESULTS: Subjectively, 65 p. 100 of the patients were very satisfied and 24 p. 100 were satisfied. According to the IKDC classification, functional outcome was in class A in 22 p. 100 and in class B in 49 p. 100. All failures (14 p. 100) except one occurred during the first year. When the meniscus was healthy or repaired, the failure rate was only 4 p. 100. Two principal factors favoring failure were severe laxity (meniscectomy) and poor femoral position. Residual laxity measured on the lateral view in the one-leg weight bearing position was 3.3 mm in the overall series, 2.4 mm for cases with isolated anterior laxity, and 4 mm for chronic laxities. Residual laxity was higher if the medial meniscus was totally or partially removed. There was no change between the 4th and 11th year of follow-up. A secondary meniscectomy was performed in 5 p. 100 of the cases despite renewed sports activity in 80 p. 100 of the cases. Osteoarthritic degeneration was the most important factor for less favorable outcome: 42 p. 100 of the cases developed preosteoarthitis or osteoarthritis. Joint degeneration occurred almost exclusively in patients who had undergone medial meniscectomy. Only 2 p. 100 of the patients with a healthy or repaired meniscus developed osteoarthritis. When the anterior laxity was the only anomaly, the functional result was very excellent, with renewed sports activity. Even in cases with persistent residual laxity, there were almost no failures or secondary meniscal lesions if the femoral position was correct. DISCUSSION: For chronic laxity, free patellar graft alone cannot avoid a high rate of failure and/or joint degeneration, particularly favored by an incorrect femoral position. Improved results can only be achieved by preserving the meniscus and possibly associating a lateral or medial plasty whose effect remains to be evaluated.

Adolescent↗

[Postoperative low patella. Treatment by lengthening of the patellar tendon].

PURPOSE OF THE STUDY: Patella infera is a post operative complication that can be prevented in most cases. This study was undertaken to determine etiological factors and to determine the means to avoid patella infera following knee surgery. The authors describe a new surgical technic to correct this complication and describe prognostic factors for achieving good results. MATERIAL AND METHODS: From 1985 to 1991, 35 patellar tendon lengthenings were performed in 35 patients. There were 28 female and 7 male patients with an average age of 37 years (21 to 72). Follow-up averaged 27 months and all patients had radiographic follow-ups. All patients had previous knee surgery: 21 for patellar pain (= patellar pain), 9 ACL reconstructions, 5 traumatic lesions. The range of motion of the knee was between 5 and 120 degrees. Patients complained of a burning pain in the patellar region and the sensation that the knee was held in a vice. The average Insall index was 0.55 (0.3 to 0.87). 25 patients had osteoporosis of the patella and 31 patients had a typical "sunrise" aspect on axial radiographs in 30 degrees of flexion. The usual diagnosis was that of algodystrophy. All patients underwent patellar tendon lengthening. RESULTS: Intra operative findings showed transverse retractions leading to resection of the medial and lateral retinaculum. The patellar tendon was short but its histological structure was normal. 15 patients had excellent results with no residual pain and were able to resume sports activities. 11 had good results with residual pain in hyperflexion and 9 had poor functional results, however nocturnal pain disappeared. Range of motion was between 0 and 130 degrees. Radiographic results were excellent since the preoperative average Insall score of 0.55 increased to 1.02 at follow-up. DISCUSSION: Patella infera is caused by combination of two factors: patellar surgery (painful patellar syndrome, patellar instability, ACL reconstruction using the mid third of the patellar tendon) and painful post operative rehabilitation with no active quadriceps contractions. To avoid this complication, the knee should be braced in 20 degrees of flexion to tense the patellar tendon and rehabilitation should be undertaken with active quadriceps contractions. Patellar lengthening is a successful procedure with the results being dependent upon number of previous surgeries, cartilage damage and, most importantly, the patellar index: between 0.8 and 0.65 the results are uncertain, < 0.6, the results are usually good. CONCLUSION: Patella infera is not a frequent complication of knee surgery. It is important to diagnose it early in order to prevent it. For chronic cases, surgical criteria should be strict: sensation of burning pain, lack of motion, unstable flexed monopodal stance, "sunrise" aspect on axial radiographs and a patellar index < 0.6. Patella infera differs from algodystrophy and re operation by retinacular release is indicated if the delay from previous surgery is < 2 months. In older cases, patellar tendon lengthening should be undertaken.

Adult↗

[Quadriceps dysplasia and patellar tilt in objective patellar instability].

PURPOSE OF THE STUDY: Dysplasia of the vastus medialis, a well-known landmark of patellar instability, is difficult to point out pre-operatively. We propose the measurement of patellar tilt on the CT scans in order to appreciate abnormality. MATERIAL AND METHODS: We studied 3 well defined groups: 143 knees operated on for a true dislocation of the patella, either for the first time or a recurrent episode, 67 asymptomatic and nonoperated contralateral knees and 54 control knees. The patellar tilt in extension was measured on the CT-scan with the quadriceps relaxed and contracted. RESULTS: The results showed the increase of the patellar tilt as an characteristic factor of patellar instability (28.8 + 10.5 degrees against 11.8 degrees + 5.7 degrees in the control group). Patellar tilt was not a consequence of the dislocation because it was also significantly increased in the asymptomatic contralateral group (17 degrees + 9 degrees). Quadricipital contraction increased the patellar tilt only in the two groups of patellar instability (+ 6 degrees) and asymptomatic contralateral group (+ 13 degrees) but not in the control group (+ 1.6 degrees). The mean of the relaxed and the contracted quadriceps patellar tilt includes the dynamic trouble. We propose the threshold of 20 degrees to determine a pathological patellar tilt. In this case, sensibility is 90 per cent and the specificity is 91 per cent. In the other patellar instability factors, only severe trochlear dysplasias involved the patellar tilt. DISCUSSION: We think that the patellar tilt in extension is a landmark of a functional disorder of the whole quadriceps muscle more than the vastus medialis only. The mean of the relaxed and contracted quadriceps patellar tilt measures permitted to point out the border cases of this functional abnormality. This measurement is reliable and can be considered pathologic above 20 degrees. The results of Insall's muscular plasty were only symptomatic because this procedure could not correct the effect of the quadricipital contraction.

Adolescent↗