"Coronal Split/Overlap Repair" Patellar Tendon Shortening in Skeletally Immature Patients.

Abstract

Background: "Coronal split/overlap repair" patellar tendon shortening (PTS) is a technique that is utilized to treat patella alta and can be combined with distal femoral extension osteotomy (DFEO) for the treatment of crouch gait in skeletally immature patients with cerebral palsy.

Description: The patellar tendon is split in the coronal plane. The ventral patellar tendon flap is released from its patellar attachment and is reflected distally over its tibial attachment, exposing a dorsal flap. Two patellar/tibial no. 5 Ethibond (Ethicon) sutures are passed through 2 crossing patellar tunnels and 2 parallel tibial tunnels. The patella is then pushed distally until its distal pole lies at the level of the tibiofemoral joint. The Ethibond sutures are tied and tensioned to the desired level. The knee should be able to be passively flexed to 90°. The intact redundant dorsal flap of the patellar tendon is imbricated. Lastly, the ventral flap is advanced proximally and sutured to the anterior surface of the patella and to the edges of the dorsal flap without shortening. A hinged knee brace is utilized postoperatively with a range of motion of 0° to 30°, progressing to 90° by 6 weeks. No resistive quadriceps contractions are permitted for the first 3 weeks.

Alternatives: Patellar tendon advancement in skeletally immature patients can be performed by releasing the tibial attachment and the free end is advanced deep to the T-shaped tibial periosteal flap^1-3. Other PTS techniques can be grouped into the categories of (1) patellar tendon imbrication⁴, (2) patellar tendon detaching techniques in which the tendon is detached from the patellar attachment or cut in its midsubstance and shortened^2,5-7, and (3) patellar tendon semi-detaching techniques in which patellar tendon flaps are created and shortened^8,9.

Rationale: The presently described technique is a semi-detaching technique, preserving a good part of the patellar tendon while avoiding complete dehiscence of the extensor mechanism. Moreover, the 2 patellar/tibial sutures would protect the patellar tendon repair and allow early rehabilitation and knee range-of-motion exercises.

Expected outcomes: Satisfactory correction of the patella alta was reported with PTS techniques with or without DFEO to correct concomitant fixed flexion deformity in patients with cerebral palsy. Furthermore, there was reported improvement of total knee range of motion with restoration of adequate knee extension during the stance phase^1,3,8. Reported complications with this technique were mainly superficial infection.

Important tips: Any substantial fixed flexion deformity of the knee (>10°) should be corrected with hamstring lengthening or DFEO prior to PTS.A mid-patellar coronal split is made with use of a no.-15 blade and extended proximally and distally with use of 2 mosquito clips.To avoid difficulties with crossing of the patellar sutures, always keep the straight needle inside the 1st tunnel until the 2nd tunnel is created and its respective suture is passed.To distalize the patella, the patellar/tibial sutures are tied in a simple knot and held by a mosquito clip in order to allow retensioning until the desired patellar height is reached.The 2 patellar/tibial suture knots are slid to the proximal and distal ends of the surgical field.

Acronyms and abbreviations: 3DGA = 3-dimensional gait analysisADL = activities of daily livingCP = cerebral palsyCPM = continuous passive motionDFEO = distal femoral extension osteotomyFAQ = Functional Assessment QuestionnaireFMS = Functional Mobility ScaleGMFCS = Gross Motor Function Classification SystemGMFM = Gross Motor Function MeasureGPS = Gait Profile ScoreGVS = Gait Variable ScoreK-wires = Kirschner wiresPTA = patellar tendon advancementPTS = patellar tendon shorteningSEMLS = single event multi-level surgery.