February issue.indd

K.L. Luscombe and N. Maffulli
Keele University School of Medicine, Department of Trauma and Orthopaedic Surgery, Hartshill, Thornburrow Drive, Stoke-on-Trent, Staffordshire, ST4 7QB

Correspondence to: N Maffulli, Department of Trauma and Orthopaedic Surgery, Hartshill, Thornburrow Drive, Stoke-on-Trent, Staffordshire, ST4 7QB Email: n.maffulli@keele.ac.uk

Introduction

Surgical procedure

Discussion

References

Keywords: Patella dislocation, lateral release, vastus medialis advancement, patellar tendon stabilisation
Surg J R Coll Surg Edinb Irel., 2 February 2004, 32-36

Recurrent patella dislocation is common, and selection of an appropriate stabilisation procedure is important for a successful outcome. We describe a combined proximal and distal realignment procedure to adjust soft tissue tension around the patella. This procedure, the ‘Three in One’ involves a combination of a lateral release, vastus medialis obliquus muscle advancement, and transfer of the medial third of the patellar tendon to the medial collateral ligament. This is a safe, reliable procedure for patients with recurrent dislocation of the patella resulting from an imbalance of soft tissue tension around the patella, but with a normally sited patella and normal trochlea

INTRODUCTION
Recurrent patella dislocation is a common orthopaedic problem. An understanding of the biomechanics of this joint and the factors contributing to its stability are important for selecting an effective operative procedure.

The patellofemoral joint consists of the patella, the medial and lateral femoral condyles and the surrounding soft tissue structures, including the medial and lateral retinacula and periarticular muscles. The function of the patella is to increase the lever arm of the quadriceps, allowing it to work more effectively to extend the knee. Patella motion during knee flexion includes some tilt and rotation so that the whole of its articular surface articulates with the femoral condyle. Patellofemoral compression forces increase during flexion up to 90o, reaching up to eight times body weight.

Passive stabilisers of the patella include the morphology of the patella and trochlea and the patellar retinaculum. In extension, the patella lies just proximal to the trochlea. As the knee flexes, it engages in the trochlea groove. Failure of the patella to engage correctly at the beginning of flexion as a result of patella alta, patella dysplasia or trochlea dysplasia may predispose to subluxation or dislocation of the patella as flexion proceeds.^1-3

Dynamic stabilisers of the patella include the periarticular muscles of the patella, especially the vastus medialis obliquus which pulls the patella medially at 65^o of knee flexion. The force vector of the quadriceps muscle is lateral to the long axis of the knee joint, forming the Q angle. This is increased in females because of a wider pelvis, increased femoral anteversion and excessive tibial torsion. The laterally directed force on the patella may be increased by an imbalance of the soft tissue tension around the patella, with deficient medial structures and tight lateral structures, leading to subluxation or dislocation of the patella. The medial retinaculum may become damaged from repeated dislocations of the patella, and wasting of vastus medialis may also be present.^1-3

Patella dislocation may be managed conservatively, with physiotherapy and strapping of the knee. However, operative management may be required for patients who experience recurrent episodes of dislocation. Surgery should be directed to correct the underlying pathology rather than a single operation being suitable for all and includes proximal and distal soft tissue procedures or tibial tubercle realignment.¹ Proximal soft tissue procedures usually involve a lateral release, which may be combined with reefing of the medial structures.^4-7 A lateral release alone may be sufficient for patients whose radiographs confirm patellar tilt alone, and following surgery the patella should be able to be passively tilted 80^o. However, in patients who present with tilt and lateralisation of the patella, additional medial tightening surgery is required, such as the Roux-Goldthwait procedure.^6,7 In this procedure, the lateral half of the patella tendon is passed under the intact medial half of the tendon before being secured to the medial aspect of the tibia.

We describe a procedure, named ‘The Three in One’ procedure by Myers et al.(1993), including both proximal and distal realignment to adjust soft tissue tension around the patella.^8,9 These procedures may be utilised in the skeletally immature patient with no risk of damage to the proximal tibial epiphysis.^8,9 It involves a combination of a lateral release, vastus medialis muscle advancement, and transfer of the medial third of the patellar tendon to the medial collateral ligament. Medial transfer of the medial third of the patellar tendon rather than the lateral half, as in the Roux-Goldthwait procedure, avoids inducing lateral patellar tilt.

Figure 1b: Completed lateral release, extending to the superolateral margin of the patella with the synovium remaining intact

PRE-OPERATIVE PREPARATION
The assessment of a patient with recurrent patella dislocation is undertaken using a combination of clinical history and examination, together with radiographic investigations. Patients describe an initial injury resulting in patella dislocation followed by repeated dislocations involving sequentially less force. Clinical examination may reveal generalised ligamentous laxity, patella dysplasia, abnormal patella position or abnormal patella glide. Gentle lateral pressure applied to the patella during flexion may produce a positive apprehension test. A lateral radiograph enables assessment of patella height.^{10, 11} An axial view may reveal patella tilt or subluxation. Computerised tomography can be used to assess the tibial tubercle trochlear groove distance, which should be less than 20 mm.¹²

We offer the three in one procedure to patients who have recurrent patella dislocation due to unbalanced soft tissue tension around the patella and no evidence of patella or trochlea dysplasia.

SURGICAL PROCEDURE
The procedure is carried out under a general anaesthetic with the patient supine on the operating table. A tourniquet is applied to the thigh, the leg exanguinated and the cuff inflated to 250 mmHg.

An initial arthroscopic examination of the knee joint is undertaken using standard lateral and medial portals. This enables assessment and debridement of the articular surface of the patella.

A 10 cm incision is made from the midpoint of the patella inferiorly to the medial aspect of the tibial tuberosity. The incision is deepened through the subcutaneous fat to the fascia, allowing visualisation of the lateral and medial retinacula, the patellar tendon, and the superomedial aspect of the patella where the vastus medialis obliquus tendon inserts.

Figure 2a: The vastus medialis is detached from the medial aspect of the patella and the site for its reattachment scarified with a burr

Figure 2b: The vastus medialis is reattached 5 to 10 mm distally with interrupted 1 vicryl sutures

A lateral release is performed, taking care to leave the synovium intact and not to extend the divisionof the lateral retinaculum proximal to the superior pole of the patella or into the muscle fibers of the vastus lateralis muscle (Figure 1a and b).

The medial retinaculum is divided to release the vastus medialis obliquus insertion and to expose the medial patellar tendon, from the superomedial corner of the patella distally, about 5mm from the edge of the medial patella and patellar tendon to the tibial tuberosity. The area on the patella for the new insertion of the vastus medialis is scarified with a burr. The vastus medialis tendon insertion is advanced 5 to 10 mm distally and laterally and secured with interrupted 1 vicryl (Ethicon, Edinburgh, UK, EH11 4HE) sutures (Figure 2a and b). The medial third of the patellar tendon is detached from its tibial insertion by sharp dissection and split from the remaining tendon, leaving it attached proximally to the patella (Figure 3). With the knee flexed to 30°, the patellar tendon is then transferred medially and sutured to the medial collateral ligament so that the transferred portion subtends an angle of 40° to 45° with the intact patellar tendon (Figure 4a and b).

The wound is closed in layers with 1 vicryl, 2/0 vicryl and 3/ 0 vicryl subcuticular sutures. A non-adherent dressing, velband and crepe bandage and a cricket pad splint are applied.

Figure 3: The medial third of the patellar tendon is detached from the tibial tuberosity

Figure 4b: The medial third of the patellar tendon is sutured in position using 1 vicryl sutures

POST-OPERATIVE MANAGEMENT
Post-operatively, patients initially mobilise nonweightbearing and are discharged home when comfortable. At two weeks, patients are allowed to progress from partial to full weight bearing. At six weeks after surgery, a programme of strengthening and restoration of range of movement is commenced. At 12 weeks after surgery, a period of sportspecific rehabilitation is started.

DISCUSSION
The selection of an appropriate operative procedure for patients who present with recurrent dislocation is important for a successful outcome. A lateral release alone may be sufficient for patients whose radiographs confirm patellar tilt alone. However, in patients who present with tilt and lateralisation of the patella additional medial tightening surgery is required. This may include transfer of the medial third or lateral half of the patellar tendon to the medial aspect of the knee. The advantage of the three in one procedure, which utilises the medial third of the patellar tendon, is that it avoids the problem of inducing lateral patellar tilt seen following the Roux-Goldthwaite procedure.^8,9

We advocate the three-in-one procedure as a safe, effective treatment for patellofemoral instability in those patients who have not responded to conservative measures.

REFERENCES
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3. Tumia N, Maffulli N: Patellofemoral pain in Female Athletes. Sports medicine and Arthroscopy Review 2002; 10: 69-75.
4. Dandy DJ, Desai SS: The results of arthroscopic lateral release of the extensor mechanism for recurrent dislocation of the patella after 8 years. Arthroscopy 1994; 10: 540 -545.
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6. Fondren FB, Goldner JL, Bassett FH III: Recurrent dislocation of the patella treated by the modified Roux-Goldthwait procedure. A prospective study of fortyseven knees. J Bone Joint Surg 1985; 67A: 993 -1005.
7. Chrisman OD, Snook GA, Wilson TC: A long-term prospective study of the Hauser and Roux-Goldthwait procedures for recurrent patellar dislocation. Clin Orthop 1979; 144: 27 -30.
8. Myers PT, Bourne R, Bulow J: The “threeinone” procedure for the unstable patella. J Bone Joint Surg 1993; 75B (Suppl I): 62.
9. Myers P, Williams A, Dodds R, Bulow J.The three-in-one proximal and distal soft tissue patellar realignment procedure. Results and its place in the management of patellofemoral instability. Am J Sports Med 1999; 27(5): 575-9.
10. Insall J, Salvati E. Patella position in the normal knee joint. Radiology 1971; 101: 101-4.
11. Blackburne JS, Peel TE. A new method for measuring patellar height. J Bone Joint Surg 1977; 59B: 241-2.
12. Goutallier D, Bernageau J, Lecudonnec B. Measurement of the tibial tuberosity, patella groove distance: technique and results. Rev Chir Orthop 1978; 64: 423-8.

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