Abstract
Background:
Fixed and habitual (obligatory) dislocation of the patella is caused by externally rotated and shortened quadriceps mechanisms. Many surgical techniques have been described to treat this condition, yet there is insufficient evidence favoring one over another. A combination of procedures is recommended to restore proper patellar tracking.
Indications:
The quadricepsplasty with medial plication and Baguette Molle is indicated in skeletally immature patients with a misaligned extensor mechanism causing habitual patellar dislocation.
Technique Description:
A lateral approach to the femur is performed, followed by dissection down to the iliotibial band fascia. The fascia is opened, and the vastus lateralis is dissected from the posterior iliotibial band fascia, exposing the femur. Distal-to-proximal release of the vastus lateralis is performed until fully released. The incision extends distally toward the tibial tuberosity, opening the lateral retinaculum and capsule. Full-thickness flaps are developed on each side of the tibial tuberosity. The apophysis of the tuberosity is sharply dissected and transposed medially within a trough in the tibial periosteum (“Baguette Molle”) and then secured with interrupted nonabsorbable sutures. Medial plication is performed through a longitudinal incision parallel to the patella's long axis. Nonabsorbable sutures are used to plicate the flap, ensuring appropriate tension. On-table assessment of patellar tracking is carried out throughout the procedure.
Results:
The patient undergoes a standard postoperative admission lasting 2 to 3 days, primarily focusing on pain management and facilitating early range of motion. A perioperative epidural catheter is inserted to ensure effective pain control and aid in early mobilization. Additionally, patients are introduced to a continuous passive motion device, dedicating 3 to 5 hours per day to mobilize the affected limb at a 45° angle on postoperative day 1, gradually progressing to full range by postoperative day 3. Subsequently, a protective weightbearing status is recommended for 4 to 6 weeks with unrestricted range of motion. Follow-up appointments are scheduled at 6 weeks, 12 weeks, 6 months, and annually thereafter until growth cessation to monitor for any potential growth disturbances.
Discussion/Conclusion:
Quadricepsplasty with medial plication and the Baguette Molle technique is a reproducible and effective procedure for treating habitual patellar dislocation in skeletally immature patients, with satisfactory short-term outcomes.
Patient Consent Disclosure Statement:
The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.
This is a visual representation of the abstract.
Video Transcript
We are discussing our institution's chosen surgical management of habitual patellar dislocation at the Shriners Children's Hospital in Montreal, Canada.
Authors’ disclosures are shown here.
Background
Habitual patellar dislocation results from dysfunction of the extensor mechanism, and this is thought to originate with lateral tethering. There are a number of surgical interventions described, but there is poor consensus in the literature regarding the best practice. Habitual dislocation may be part of a spectrum of disease, and our technique is designed to provide appropriate steps to deal with increasing severity. Our technique describes quadricepsplasty, medial plication, and Baguette Molle for medialization of the patellar tendon insertion. All our short-term outcomes are satisfactory, and likewise in the literature, long-term data are lacking.
The cause of both fixed and habitual dislocation of the patella is an externally rotated and/or shortened quadriceps mechanism. 3 Quadricepsplasty is a surgical procedure originally described by Judet, which has been commonly used to treat pediatric patients with congenital or obligatory patellar dislocation. 5 The goal of the procedure is to allow correction of the externally rotated or laterally tethered quadriceps by releasing from its lateral tether along its entire length.
The mechanism is composed of the quadriceps muscle, which becomes the quadriceps tendon, inserting into the patella of the patellar tendon, attaching distally to the tibial tubercle.1,2,4
There are a number of classification systems in place, but obligatory and habitual dislocation are often used interchangeably in these. We tend to use the Green classification from an academic point of view. 7
Indications
We present the case of a 7-year-old boy whose parents noticed his patella dislocating laterally over the course of 6 months. There was no history of trauma, but the patient did have difficulty running due to pain and associated his symptoms with recurrent falls. Medical history was normal. The physical examination of the symptomatic right knee revealed normal lower limb alignment. The patella had 2 quadrants of lateral displacement with the knee in extension. There was clear obligatory dislocation of the patella out of the trochlea at 40° of knee flexion. The patella was noted to relocate when bringing the knee back into extension.
These are the patient's preoperative radiographs, which, on the skyline view, show lateral position of the patella over the distal femur with evidence of trochlear dysplasia.
Treatment options and decision-making: Unlike congenital or fixed patellar dislocation, there are reasonable options for nonoperative treatment. These include patellar stabilizing sleeves or J-braces. From an operative view, first is the lateral tether, which is addressed via lateral retinacular release from the abnormal iliotibial (IT) band and vastus attachments. This is followed by a quadricepsplasty, which is an extraperiosteal release of the vastus from the femur as well as from the fascia of the IT band. This is done in a progressive manner from distal to proximal. Intraoperatively, we check to see at what point the quadriceps mechanism centralizes or allows the patella to centralize. This may involve release all the way up to the vastus ridge as needed. Patellar tendon realignment or the need for this can be assessed intraoperatively as needed. Once the patella has centralized, the line of pull of the patellar tendon can be assessed and the need for correction identified. Our chosen technique for this is a Baguette Molle in the skeletally immature or a tibial tubercle transfer in the skeletally mature patient. The median soft tissues are attenuated and elongated and require plication to maintain the reduction of the patella. Again, intraoperative assessment is important in deciding whether more significant intervention in the form of medial patellofemoral ligament (MPFL) reconstruction or vastus medialis oblique (VMO) advancement may be required, although these are typically not employed in our institution.
Preoperatively, knee radiographs with skyline views and full-length lower extremity radiographs are obtained. Consent for surgery should include possible complications such as infection or vascular injuries, extensor leg, avascular necrosis of the patella, and failure to ameliorate the dislocation. The patient is positioned supine on the operating table, and examination under general anesthesia of the knee is performed to confirm the operative plan.
Technique Description
The knee is examined under general anesthesia. Obligatory dislocation of the patella laterally is demonstrated here at approximately 45° of knee flexion. The extensile incision is marked out on the skin as for a standard lateral approach to the femur. Following dissection down to fascia of the IT band, the fascia is opened from distal to proximal. The vastus lateralis is dissected from the fascia of the IT band and the posterior compartment. The dissection is carried proximally, exposing the femur extraperiosteally with care taken to identify and cauterize the perforating vessels. We perform a full release of the vastus lateralis from the anterolateral part of the femur in a sequential manner from distal to proximal. Last, the vastus lateralis is released from the vastus ridge. At this point, the vastus lateralis muscle has been completely elevated from the femur and is mobile. This release alone may allow the patella to track normally in the trochlea, eliminating the obligatory lateral dislocation. We then extend our incision distally toward the midline, centering over the tibial tuberosity, releasing the lateral retinaculum, and incising the lateral capsule. This process removes the lateral tethering attachment distally. Full-thickness flaps are developed on each side of the tibial tuberosity. At this point, assessment of the patellar tendon and its line of pull is made. Extra-periosteal dissection is performed to mobilize the tendon from the medial and lateral tissues. The goal now is to elevate the apophysis of the tuberosity from the proximal tibia. The apophysis can now be sharply dissected from its bed. The blade is parallel to the bone, and care is taken not to amputate the apophysis of the tendon, leaving the distal-most soft tissue insertion intact. This is the Baguette Molle. Avoiding damage to the underlying physis is key, and so judicious use of the knife in the corridor between the apophysis and the physis is paramount. Here, that dissection is clearly demonstrated with the distal attachment seen. The Baguette is now ready to be transposed, moving it about its distal fixed point from lateral to medial. Here, the planned transposition is seen. With the patellar tendon retracted laterally, the periosteum of the tibia is opened medially, and a trough is created to house the transposed apophysis. This allows the periosteum to be raised in a flap over the apophysis. Nonabsorbable sutures are now used in an interrupted fashion to relocate the tendon within its medial subperiosteal bed. This is done distal-most initially, at which point the change in line of pull of the tendon can be assessed by flexing the knee. Once the changed line of pull is found to be satisfactory, further sutures are then placed to complete the repair. Satisfactory patellar tracking intention is demonstrated here after transposition. Medial plication is then performed through a 3-cm longitudinal incision parallel to the long axis of the patella. A full-thickness flap through the capsule is created. The plication is simulated here. Nonabsorbable sutures are used to plicate the flap. The knee is then ranged to ensure appropriate medial and lateral tension. The subcutaneous tissue should be closed laterally before this to avoid underestimating the lateral tension. Final on-table assessment is performed demonstrating satisfactory outcome.
Complications for the procedure include lengthening of the extensor mechanism with residual extension leg, injury to the quadriceps tendon, tibial physis injury via the Baguette Molle, infection including deep sepsis, skin necrosis or wound dehiscence secondary to centralization of the extensor mechanism, or delayed wound healing. Skin complications are more typically encountered with chronic dislocations where the patella has never been centralized.
Results
Postoperatively, the patient is admitted to the hospital with a focus on pain management and early range of motion with physical therapy. Continuous passive-motion therapy is employed 3 times per day, starting with 0° to 45° on postoperative day 1 with gradual progression to full range of motion on postoperative day 3. The patient is allowed weightbearing with crutches in a Zimmer splint over the first 6 weeks and has unrestricted range of motion instructions with physical therapy. The patient is followed at sequential intervals and all the way up to skeletal maturity with progressive return to noncontact activity initially and sport when physical milestones are met in terms of quad strength. Follow-up also includes monitoring for any potential growth disturbances, and we typically use a patella centering brace once the Zimmer splint is discontinued.
This slide outlines typical return to sport guidelines that we utilize. 6
Discussion/Conclusion
As mentioned previously, the literature is scant and limited to case series and case studies. This slide shows 1 such case series of 12 knees with habitual or fixed patellar dislocation. 8 These studies are typically short term, which show satisfactory outcomes in up to 90% with a 10% to 20% redislocation rate.
Pearls and pitfalls of the procedure: Adequate surgical exposure is key. The incision needs to be planned to provide appropriate access to both the lateral compartment of the thigh and the tibial tubercle as well as the lateral structures. At the level of the patella, intraoperative reassessment is important after each individual corrective step. The vastus lateralis should be fully released extraperiosteally from the femur as far proximally as needed. Sharp elevation of the tibial tubercle apophysis should be done while respecting the underlying physis. Transposition of the Baguette Molle should be done temporarily to allow the new line of pull of the tendon to be assessed before final placement in its new subperiosteal bed. The lateral subcutaneous tissue should be closed before medial plication to avoid underestimating the lateral tension. The deep lateral tissues following release are left open. Perioperatively, an epidural catheter is used for pain control, which aids in early mobilization. Continuous passive motion should be used while the patient is an inpatient and the decision on discharge made whether they would benefit from the same in the outpatient setting.
Footnotes
One or more of the authors has declared the following potential conflict of interest or source of funding: J.D. is a paid consultant for DePuy Synthes. T.P. is a paid consultant for Smith & Nephew and Pandopharm. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
