Special Considerations for Pediatric Patellar Instability

GALEAZZI TECHNIQUE

One of the first and most famous soft-tissue techniques to address patellar instability was the semitendinosus tenodesis, published by Galeazzi¹⁵⁴ in 1922 (Figure 7). This technique stabilizes the patella without altering the TT. In the original technique, a portion of the semitendinosus tendon is harvested with its tibial insertion left intact. The free end of the tendon is then secured with sutures at the periosteal groove of the medial patella.^154,155 Fiume¹⁵⁶ modified this technique by adding a lateral release and medial retinacular reefing. The most recent addition to this procedure was introduced by Baker and colleagues,¹⁵⁷ in which a tunnel is drilled from the medial to the lateral border of the patella. Tension placed on the grafted tendon is used to reposition the patella medially and draw it downward. Preliminary literature on this modified procedure reported fair clinical results with success rates of approximately 75%.^155,158-160 A recent study evaluating both the clinical and radiographic outcomes of this technique also indicated that while clinical results were excellent in 62.5% of patients, this technique alone was unsuccessful in fully addressing patellar instability in patients with underlying anatomic abnormalities such as patellar alta.¹⁶¹ In light of these less than ideal reports, the authors no longer recommend this technique for patellofemoral instability cases.

ROUX-GOLDTHWAIT PROCEDURE

The Roux-Goldthwait procedure, first described by both Roux¹⁶² and Goldthwait¹⁶³ in 1888 and 1895 respectively, was later modified in 1985 to involve a lateral release, plication of the medial retinaculum, medial transfer of the lateral patellar tendon without advancement, and advancement of the vastus medialis (Figure 8).¹⁶⁴ More recently, Marsh and colleagues¹⁵² introduced an addition to aligning the extensor mechanism with the femoral shaft better. In this technique modification, the patellar tendon is split longitudinally, and its lateral half is detached and transferred distally beneath its medial half. The free end is then sutured to the periosteum on the medial side of the tibia.¹⁵² With a mean long-term follow-up of 6.2 years, Marsh and colleagues¹⁵² reported excellent results in 65%, good in 11%, and fair in 3% of the knees operated on with this modified technique. Of the patients in this cohort whose strength was evaluated, 80% had their strength returned to 90% of preoperative levels in the operated leg.¹⁵² While this study and others report improved outcomes, an increasing body of literature has found high rates of recurrence, patella infera, and other complications following the modified Roux-Goldthwait procedure.^36,165-171 Also, a study comparing MPFL reconstruction using adductus magnus transfer with the Roux-Goldthwait procedure reported that patients in the MPFL cohort reported less pain postoperatively.¹⁵⁰ In addition, whereas the Kujala and Lysholm scores, recurrence rates, patellofemoral angles, and apprehension test results did not demonstrate significant differences between these 2 groups, the MPFL group had significantly fewer abnormal congruence angles, better patellar medialization, and higher peak torque of the hamstring.¹⁵⁰

COMBINED MPFL AND MEDIAL PATELLOTIBIAL LIGAMENT RECONSTRUCTION

While the medial patellotibial ligament (MPTL) has not received much attention with regard to patellar stability, recent studies have indicated its role during higher degrees of both flexion and extension.¹⁷² The MPTL acts as a secondary restrictor ligament which helps release stress on the MPFL by decreasing the Q angle and further normalizing patellar kinematics.¹⁷³ Patients who present with hyperlaxity or knee hyperextension combined with extension subluxation and flexion instability could be indicated for this additional stabilizing procedure. Both Nietosvaara and colleagues⁸⁵ and Brown and Ahmad¹⁷⁴ have described a dual MPTL and MPFL reconstruction technique using a semitendinosus hamstring graft. More recently Hinckel and colleagues¹⁷² described a combined MPFL and MPTL reconstruction, using a graft from the quadriceps tendon to reconstruct the MPFL and one from the patellar tendon to reconstruct the MPTL. In this technique, once the respective grafts have been harvested, a femoral insertion for the graft recreating the MPFL is fluoroscopically established so that an anchor can be inserted distal to the femoral physeal growth plate. For the MPTL insertion, attachment to the tibia below the joint line and 2 cm medial to the patellar tendon is established fluoroscopically just above the physeal growth plate on the proximal epiphysis.^19,175 The MPTL graft is sutured first with the knee at 90° of flexion to establish tension similar to that of the patellar tendon.¹⁷⁶ Then, the knee is placed in 30° of flexion to fix the MPFL graft to the medial patella to prevent excessive lateral translation of the patella.

PATELLAR TENDON TRANSFER

Patellar tendon transfer with proximal realignment is a technique used in particularly young patients to address cases of patellofemoral instability involving concomitant bony or anatomic abnormalities. This procedure is effective for young children with substantial amounts of remaining growth as it better mimics native anatomy than other realignment procedures and does not require bony remodeling.^152-154 It is important to familiarize with surgical techniques to address malalignment issues in young patients as neglected alignment issues can lead to worsening of trochlear dysplasia and instability, which are very difficult to treat later on when patients are older.¹⁵³

The patellar tendon transfer technique (Figure 9), as described by Gordon and Schoenecker,¹⁷⁷ starts with an extensive lateral retinacular release. The patellar tendon is then released from its distal insertion at the TT so that it can be moved medially without moving it inferiorly. After confirming patellar tracking and alignment by flexing the knee from 0° to 90° with the graft in place, the patellar tendon graft is secured with multiple nonabsorbable horizontal sutures.¹⁷⁷ Of note, in skeletally mature patients, a TT osteotomy is used to accomplish the same goal. This osteotomy has been shown to improve both patellar height and TT-TG distance in skeletally mature patients, but is contraindicated in skeletally immature patients.^92,178

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