Article

Patellofemoral Instability in the Skeletally Immature Patient: A Review and Technical Description of Medial Patellofemoral Ligament Reconstruction in Patients with Open Physes

Publish date: December 18, 2018

References

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TREATMENT OPTIONS

The evaluation of a skeletally immature patient may differ from that of an adult patient. (Table 1) represents a standard evaluation of a skeletally immature patient with PFI. The injury, physical examination findings, activity level, presence of an osteochondral fracture, and severity of bony dysplasia may indicate surgical treatment and influence selection of the surgical technique. Indications for surgical treatment include recurrent patellar instability, symptomatic patellar instability, the presence of a chondral or an osteochondral fracture, and a primary patella dislocation in patients with a high risk for recurrent dislocations. Table 2 represents a list of the possible surgical treatment options for the skeletally immature patient with PFI.^21,22 Variable outcomes and recurrence rates are noted with each procedure.^21,22

MPFL REPAIR VS RECONSTRUCTION

Although there is increased consensus for restoring normal anatomy, continued controversy exists regarding the utility of an MPFL repair versus reconstruction. An MPFL repair to the patella has been reported in a large series and was noted to have a 72% success rate.²³ Although a perceived benefit of the procedure is the absence of risk to the physis, concerns exist regarding the unacceptable rate of continued patellar instability after a repair of native tissue.

Several studies have demonstrated that reconstruction of the MPFL yields lower rates of recurrent dislocation, improved knee function, and an ability to return to prior levels of activity with little to no functional impairment.^1,2,24-26 Studies have also shown that MPFL reconstruction can be performed safely in skeletally immature patients, with little risk of growth impairment, good to excellent results, and low re-rupture rates.^27,28

We propose that MPFL reconstruction for the skeletally immature patient with PFI should be the primary surgical treatment. Any patient with atypical or severe bony dysplasia may warrant additional intervention. Additional correction of valgus, in the form of guided growth, should be considered in conjunction with an MPFL reconstruction if the patient demonstrates a valgus of grade >2 or a lateral distal femoral angle of <84°.

GRAFT OPTIONS

When an MPFL reconstruction is indicated, graft options include autologous hamstring, quadriceps, adductor, or patellar tendon grafts. Allograft tendon may be an acceptable choice, and use of synthetic graft has also been described. A recent systematic review²⁹ concluded that there was no difference in recurrence rates or outcomes based on graft type. However, in this study, the overall complication rates were higher in patients who had autologous graft than in those who had allograft. Although the use of allograft has not been specifically reported in a pediatric cohort, allografts have been successfully used in this age group. Obviating graft harvest eliminates an additional or extended incision, limits postoperative weakness, and may speed early recovery.

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