Patellofemoral contact pressures and lateral patellar translation after medial patellofemoral ligament reconstruction.
ABSTRACT Overtensioning of medial patellofemoral ligament reconstructions may lead to adverse surgical outcomes.
Increasing tension on a medial patellofemoral ligament graft will increase patellofemoral contact forces and decrease lateral patellar translation.
Controlled laboratory study.
Patellofemoral contact pressures were measured in 8 fresh-frozen cadaveric knees before and after transection of the medial patellofemoral ligament and after a standardized reconstruction surgery. Contact pressures were measured at 3 knee angles (30 degrees , 60 degrees , and 90 degrees ) and under 3 levels of tension applied to the graft (2, 10, and 40 N). For each condition, patellar translation was measured at 30 degrees of knee flexion as a 22-N lateral force was applied.
Graft tension of 2 N restored normal translation, but 10 N and 40 N significantly restricted motion (5.2 mm and 1.9 mm, respectively). Compared with the intact knee, medial patellofemoral contact pressures significantly increased (P < .05) when 40 N of tension was applied to the reconstruction. Medial contact pressures were restored to normal with 2 N of graft tension. Lateral patellar translation was significantly greater (P < .05) after the medial patellofemoral ligament was cut (16.3 mm) compared with intact (7.7 mm).
Low (2-N) tension applied to a medial patellofemoral ligament reconstruction stabilized the patella and did not increase medial patellofemoral contact pressures. Higher loads (10 N and 40 N) progressively restricted lateral patellar translation and inappropriately redistributed patellofemoral contact pressures.
Overtensioning can be avoided by applying low loads to medial patellofemoral ligament reconstructions, which reestablished normal translation and patellofemoral contact pressures.
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ABSTRACT: Many surgical techniques for the medial patellofemoral ligament have recently been suggested, all of which included problems identifying the femoral anchorage point and determining the proper extent of knee flexion for the transplant. P. Burdin proposed a different and original approach consisting in performing a gracilis muscle transfer to the medial edge of the patella, thus obtaining progressive tension of the transfer during knee flexion by means of the myotatic reflex. We report the results herein. We retrospectively assessed 17 knees treated for patellofemoral instability using this technique. Two cases presented subjective patellofemoral instability and 15 presented objective patellofemoral instability. The patients' mean age was 17.4 years (range, 8-47 years) during the first episode of dislocation. Two cases of instability were secondary to advanced neuromuscular disease. Two knees had already undergone two stabilization attempts. Fifteen knees presented trochlear dysplasia (four stage A, eight stage B, and three stage C). The mean age at surgery was 28.2 years (range, 16-47 years). In 15 cases, the gracilis transfer was associated with lowering the anterior tibial tuberosity (mean, 10mm). No patellar fracture occurred. A persistent sensory deficit of the anterior branch of the internal saphenous nerve was observed in 15 cases. One knee remained painful and retained subjective instability; total knee arthroplasty was performed 3 years after the intervention. The mean follow-up at revision was 5.5 years (range, 1.5-16.5 years). No recurrence of dislocation was reported. Eight cases retained subjective instability. The SF-36 and IKDC scores were good or excellent in 12 cases and the KOOS was good or excellent in 13 cases. Radiologically, patellar tilt persisted in six cases out of 14, translation persisted in two cases out of 14, and secondary patella baja was observed in one. Medial patellofemoral osteoarthritis was observed in five cases: one case IWANO stage I and four cases IWANO stage II. These satisfactory results seem stable over time and were acquired using a simple procedure with reduced morbidity, making it possible to avoid significant displacement of the anterior tibial tuberosity and stabilize the extensor apparatus. It can also be hoped that the onset of secondary patellofemoral osteoarthritis, undoubtedly inevitable, has been delayed.Orthopaedics & Traumatology Surgery & Research 06/2011; 97(4 Suppl):S5-11. DOI:10.1016/j.otsr.2011.03.013 · 1.17 Impact Factor
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ABSTRACT: The medial patellofemoral ligament (MPFL) ensures stability of the patella against lateral forces. In cases of recurrent lateral patellar luxation, surgical reconstruction of the MPFL has an important role in treating lateral patellar instability. Several biomechanical studies have presented valuable pieces of information about various techniques for re-creating this medial patellofemoral complex mainly using the gracilis tendon as an autograft. However, with the increasing number of MPFL reconstructions, there are also an increasing number of patients requiring revision MPFL reconstruction. Therefore alternative graft options may become more relevant. Furthermore, the gracilis tendon as a tubular graft may not be able to fully restore patellofemoral kinematics compared with the native MPFL. This article introduces a surgical technique using the fascia lata as an alternative graft option for the anatomic reconstruction of the MPFL.02/2015; 4(1). DOI:10.1016/j.eats.2014.11.005
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ABSTRACT: Among the numerous techniques available, medial patellofemoral ligament (MPFL) reconstruction is increasingly used for the surgical treatment of objective patellar instability. The main objective of the present study was to assess efficacy in preventing recurrence of patellar dislocation and in correcting radiographic patellar tilt. The study hypothesis was that MPFL reconstruction, isolated or with associated bone surgery, by restoring “favorable” graft anisometry, provides a good trade-off between patellar stability and absence of postoperative stiffness.Orthopaedics & Traumatology Surgery & Research 12/2014; 101(1). DOI:10.1016/j.otsr.2014.09.023 · 1.17 Impact Factor