Anterior Advancement of the Tibial Tuberosity: The Maquet Procedure

INTRODUCTION TO TIBIAL TUBEROSITY ADVANCEMENT

The management of isolated, severe patellofemoral osteoarthritis and recalcitrant patellofemoral pain syndromes in the young, active patient remains a formidable challenge in orthopaedic surgery. Historically, Maquet and Murray recommended the anterior advancement of the patellar tendon at the tibial tuberosity to mechanically relieve the compressive effect of the patella on the underlying femoral condyles.

By anteriorly displacing the tibial tuberosity, the procedure fundamentally alters the extensor mechanism's biomechanics. While the advent of modern patellofemoral arthroplasty has narrowed the indications for isolated anterior tuberosity advancement, the "Maquet Procedure" and its contemporary modifications remain critical joint-preserving tools in the armamentarium of the reconstructive knee surgeon. This is particularly true for patients who are too young or physically demanding for arthroplasty, yet suffer from debilitating anterior knee pain driven by mechanical overload.

BIOMECHANICAL RATIONALE AND KINEMATIC EFFECTS

The patellofemoral joint is subjected to some of the highest biomechanical loads in the human body, with joint reaction forces reaching up to seven times body weight during deep flexion activities such as squatting or stair climbing. The primary objective of the Maquet procedure is to increase the lever arm of the extensor mechanism.

The Lever Arm and Contact Forces

By advancing the tibial tuberosity anteriorly, the distance between the center of rotation of the knee and the line of action of the patellar tendon is increased. According to the principles of static equilibrium, an increased lever arm dictates that less quadriceps force is required to generate an equivalent extension moment. Consequently, the patellofemoral joint reaction force (PFJRF) is significantly diminished.

🔬 Clinical Pearl: Finite Element Analysis

A comprehensive finite element study confirmed the effectiveness of anterior tuberosity advancement in reducing patellofemoral contact forces, especially at smaller flexion angles. Maximal contact stress is substantially decreased at full extension. However, surgeons must be aware of the kinematic trade-off: contact stresses can actually increase at 90 degrees of flexion due to the altered vector of the patellar tendon.

Global Knee Kinematics

The anterior elevation of the tibial crest does not occur in a biomechanical vacuum. Substantial secondary effects of tuberosity elevation have been documented, including alterations in:
* Tibial Kinematics: Changes in the resting position of the tibia relative to the femur.
* Cruciate Ligament Forces: Anterior advancement can increase strain on the anterior cruciate ligament (ACL) while unloading the posterior cruciate ligament (PCL).
* Tibiofemoral Contact Forces: Altered extensor vectors can shift load distributions within the medial and lateral tibiofemoral compartments.
* Extensor Lever Arm: The primary intended effect, optimizing the mechanical advantage of the quadriceps.

Surgeons are cautioned that the effect of the procedure on the entire knee joint, not just the isolated patellofemoral compartment, must be meticulously considered during preoperative planning.

INDICATIONS AND PATIENT SELECTION

Patient selection is the most critical determinant of success for tibial tuberosity advancement. The procedure is highly specific and unforgiving of poorly chosen candidates.

Primary Indications

• Isolated Patellofemoral Osteoarthritis: Symptomatic, radiographically confirmed Outerbridge Grade III or IV chondral wear isolated to the patellofemoral joint.
• Failed Conservative Management: Exhaustion of physical therapy, NSAIDs, bracing, and intra-articular injections.
• Age and Activity Level: Typically reserved for younger, active patients (under 50 years of age) who wish to delay arthroplasty.

Contraindications

• Tibiofemoral Arthritis: Any significant degenerative change in the medial or lateral compartments is an absolute contraindication.
• Inflammatory Arthropathy: Rheumatoid arthritis or other systemic inflammatory conditions.
• Severe Patella Alta or Baja: Unless the procedure is combined with a distalization or proximalization vector (e.g., Fulkerson osteotomy).
• Compromised Soft Tissue Envelope: Poor anterior tibial skin quality, previous extensive scarring, or active infection.

PREOPERATIVE PLANNING

Meticulous preoperative imaging is required to map the osteotomy and determine the exact degree of advancement needed.

1. Standard Radiographs: Weight-bearing anteroposterior (AP), lateral in 30 degrees of flexion, and Merchant/skyline views. The lateral view is critical for assessing patellar height (Caton-Deschamps or Insall-Salvati ratios) and baseline tuberosity morphology.
2. Advanced Imaging (CT/MRI): MRI is invaluable for confirming the absence of tibiofemoral chondral damage and assessing the exact location of patellofemoral lesions. CT scans are utilized to measure the Tibial Tuberosity-Trochlear Groove (TT-TG) distance. If the TT-TG distance exceeds 20 mm, a medialization vector should be incorporated into the advancement.

SURGICAL TECHNIQUE: THE MAQUET PROCEDURE

The classic Maquet technique involves the elevation of a massive tongue of bone to prevent fracture and ensure adequate healing. The following steps detail the optimized, textbook approach to this complex osteotomy.

1. Positioning and Anesthesia

• The patient is placed supine on a radiolucent operating table.
• A well-padded high thigh tourniquet is applied.
• The operative leg is prepped and draped free to allow full, unhindered range of motion during the procedure.
• A bump may be placed under the ipsilateral hip to control external rotation.

2. Surgical Approach and Exposure

• Incision: Make a longitudinal medial parapatellar incision. The incision must be carried distal to the tibial tuberosity, extending along the anteromedial aspect of the tibia to accommodate the long osteotomy.
• Soft Tissue Dissection: Create full-thickness fasciocutaneous flaps. Avoid undermining the skin edges to preserve the tenuous vascular supply of the anterior tibial skin.
• Tendon Mobilization: Dissect the patellar tendon along its posterior surface. Carefully loosen and excise a portion of the infrapatellar fat pad. This step is critical to permit the patella to ride free without tethering during the advancement.

3. Intra-articular Inspection and Preparation

• Open the joint medially through the parapatellar arthrotomy.
• Thoroughly inspect the patellofemoral and tibiofemoral compartments.
• Correct any intra-articular abnormalities as indicated (e.g., removal of loose bodies, debridement of unstable chondral flaps, or treatment of meniscal pathology).

4. The Tibial Crest Osteotomy

The dimensions of the osteotomy are paramount to prevent catastrophic fracture of the tibial crest.

• Marking the Osteotomy: Outline the tuberosity on the anteromedial aspect of the tibia.
• Dimensions: Carefully elevate a tongue of bone, composed of the tibial tuberosity and the attachment of the patellar tendon. The standard dimensions for a classic Maquet elevation are:
  • Thickness: 2.0 cm
  • Width: 2.5 cm
  • Length: 11.5 cm
• Execution:
  • Drill a transverse hole at the planned distal extent of the osteotomy (11.5 cm distal to the tuberosity) to act as a stress-reliever and prevent distal propagation of the fracture into the tibial shaft.
  • Use an oscillating saw to make the longitudinal cut from proximal to distal, tapering smoothly into the distal drill hole.
  • Use broad, flexible osteotomes to gently pry the bone tongue anteriorly, hinging on the intact distal periosteum and bone bridge.

⚠️ Surgical Warning: The Distal Hinge

The distal cortical hinge is the most vulnerable point of the osteotomy. Aggressive or rapid elevation will cause the hinge to snap, converting a controlled greenstick fracture into a free-floating bone block, which drastically increases the risk of nonunion and requires complex rigid fixation. Elevate the crest millimeter by millimeter.

5. Anterior Advancement and Grafting

• Once the tibial crest is elevated, advance the tuberosity anteriorly. The standard advancement is typically between 1.0 cm and 2.0 cm, depending on preoperative calculations.
• Bone Grafting: Insert a pre-shaped tricortical iliac crest autograft or a structural allograft block into the gap behind the elevated tuberosity to maintain the anterior displacement.
• Cosmetic Considerations: In a modification of the classic technique, the proximal part of the tibia is regularly widened and contoured. This is done to prevent the creation of a cosmetically significant and highly prominent bulge at the level of the tibial tuberosity, which can cause severe discomfort when kneeling.

6. Fixation

• While the distal hinge provides some stability, rigid internal fixation is mandatory to allow early rehabilitation.
• Secure the advanced bone tongue and the intercalary graft using two or three 4.5 mm fully threaded cortical screws or 6.5 mm partially threaded cancellous screws, directed from anterior to posterior.
• Ensure the screw heads are countersunk to prevent hardware irritation beneath the anterior skin.

7. Closure

• Deflate the tourniquet and achieve meticulous hemostasis. Hematoma formation under the compromised anterior skin flap is a primary cause of wound necrosis.
• Close the arthrotomy and the deep fascial layers securely.
• Close the skin with tension-free, interrupted non-absorbable sutures. If skin tension is excessive due to the advancement, prophylactic relaxing incisions or delayed closure techniques may be required.

POSTOPERATIVE REHABILITATION PROTOCOL

The rehabilitation following a Maquet procedure must balance the need for early range of motion (to prevent arthrofibrosis) with the protection of the healing osteotomy.

Phase I: Maximum Protection (Weeks 0-2)

• Weight Bearing: Touch-down weight bearing (TDWB) with crutches.
• Immobilization: Knee locked in full extension in a hinged knee brace.
• Range of Motion (ROM): Passive ROM from 0 to 30 degrees. Avoid active knee extension to prevent avulsion of the osteotomy.
• Therapy: Isometric quadriceps sets, straight leg raises (in the brace), and ankle pumps to prevent deep vein thrombosis.

Phase II: Moderate Protection (Weeks 2-6)

• Weight Bearing: Progress to partial weight bearing (PWB), reaching 50% by week 6.
• Immobilization: Brace unlocked for ambulation as quad control improves.
• ROM: Gradually progress passive and active-assisted ROM. Goal is 90 degrees of flexion by week 6.
• Therapy: Initiate closed kinetic chain exercises (e.g., mini-squats, leg press) within the pain-free and restricted ROM arc.

Phase III: Minimum Protection (Weeks 6-12)

• Weight Bearing: Progress to full weight bearing (FWB) as tolerated, pending radiographic evidence of osteotomy consolidation.
• Immobilization: Discontinue brace once FWB is achieved without a limp and straight leg raise is performed without an extensor lag.
• ROM: Progress to full, unrestricted ROM.
• Therapy: Advanced strengthening, stationary cycling, and proprioceptive training.

Phase IV: Return to Activity (Months 3-6)

• Initiate sport-specific training, plyometrics, and agility drills.
• Full return to high-impact activities is typically permitted at 6 months, provided there is complete radiographic union and symmetric quadriceps strength (at least 85% of the contralateral limb).

COMPLICATIONS AND AVOIDANCE STRATEGIES

The Maquet procedure is historically associated with a high complication rate, which led to the development of modern modifications (such as the Fulkerson anteromedialization). Surgeons must be vigilant regarding the following pitfalls:

1. Skin Necrosis

The most feared complication of the classic Maquet procedure is necrosis of the anterior tibial skin flap. The anterior advancement stretches the skin, compromising its subdermal plexus.
* Avoidance: Utilize full-thickness flaps. Avoid advancements greater than 2.0 cm. Ensure meticulous hemostasis. If the skin is blanched upon closure, the advancement must be reduced, or a plastic surgery consultation for a rotational flap should be considered.

2. Tibial Crest Fracture

Fracture of the distal hinge or the bone tongue itself can occur during elevation or postoperatively.
* Avoidance: Adhere strictly to the recommended dimensions (11.5 cm length, 2.0 cm thickness). Always drill a distal stress-relief hole before making the longitudinal saw cut.

3. Nonunion or Delayed Union

Failure of the osteotomy to heal is typically secondary to inadequate fixation, thermal necrosis during the saw cut, or poor graft incorporation.
* Avoidance: Use copious irrigation during all saw cuts. Ensure rigid compression across the osteotomy site with lag screws. Utilize high-quality autograft or structural allograft.

4. Altered Knee Kinematics and Pain

As noted in finite element studies, over-advancement can lead to increased contact stresses at 90 degrees of flexion, resulting in persistent deep knee pain during squatting.
* Avoidance: Tailor the amount of advancement to the patient's specific anatomy and preoperative imaging. Do not universally apply a 2.0 cm advancement if a 1.0 cm advancement achieves the necessary mechanical offloading.

CONCLUSION

The anterior advancement of the tibial tuberosity remains a powerful biomechanical intervention for the treatment of isolated patellofemoral disease. By meticulously elevating a precisely measured tongue of bone and advancing it anteriorly, the surgeon can dramatically increase the extensor mechanism's lever arm, thereby reducing debilitating patellofemoral contact forces. While technically demanding and fraught with potential soft-tissue complications, strict adherence to the indications, precise surgical execution, and a phased rehabilitation protocol can yield excellent, joint-preserving outcomes for the appropriately selected patient.