Patella re-alignment in children with a modified Grammont technique

Abstract

Background and purpose: In skeletally immature patients, surgical options due to recurrent patella dislocation are limited, because bony procedures bear the risk of growth disturbances. In this retrospective study, we report the long-term functional and radiographic outcome in skeletally immature patients using the modified Grammont surgical technique.

Patients: Between 1999 and 2004, 65 skeletally immature knees (49 children) were treated with a modified Grammont procedure: an open lateral release and a shift of the patella tendon insertion below the growth plate on the tuberositas tibia, allowing the tendon to medialize. At mean 8 (5.6-11) years after surgery, 58 knees in 43 patients were evaluated by clinical examination, from functional scores (Lysholm, Tegner), and from radiographs of the knees.

Results: Mean Lysholm score was 82 postoperatively. Tegner score decreased from 6.2 to 5. Eight knees had a single dislocation within 3 months of surgery. 3 knees had repeated late dislocations, all with a high grade of trochlea dysplasia. 6 knees showed mild signs of osteoarthritis. No growth disturbances were observed.

Interpretation: The modified Grammont technique in skeletally immature patients allows restoration of the distal patella tendon alignment by dynamic positioning. Long-term results showed that there were no growth disturbances and that there was good functional outcome. However, patients with a high grade of trochlea dysplasia tended to re-dislocate.

Figure 1.

a. Lateralized left patella tendon shown through incision. * lateral fixed patellar ligament. b. The patella tendon dissected sharply from the tibial tuberosity. Then the periosteum gets detached from the tibial crest by using a rasp (° tibial tuberosity, * patellar ligament). c. New medialized position of the patella tendon through the incision (° tibial tuberosity, * detached patellar ligament).

Figure 2.

Schematic drawing of left knee. a. Following arthroscopy, a lateral incision was made starting at the mid-patellar level and extending distally to include the anterolateral arthroscopy portal to reach 1 cm below the tibial tuberosity. b. and c. In cases with concomitant osteochondral fragments, the incision was extended proximally allowing access to the lateral femoral condyle or the patella facet (red). Starting at the tibial tuberosity, the periosteum was split along the tibial crest for 6–8 cm distally without opening the fascia of the tibialis anterior muscle (red). The periosteum was subsequently detached from the tibial crest with a large rasp (blue). In knee flexion, the patella tendon then slides spontaneously medially to track within the femoral groove. Patella alignment was restored (green).

Figure 3.

a. Sagittal-plane view of the proximal tibia (deep incision) indicating the relation of the patellar tendon insertion and the anterior tongue of the physis. Note that the physis remains untouched. LP: ligamentum patellae; TA: anterior tongue of the physis; Pe; periosteum. b. The patella tendon gets sharply dissected from the tibial tuberosity. The periosteum is then split along the tibial crest and detached distally by rasp. This leads to a spontaneous slide of the patella tendon medially.