Complex decision-making in patellofemoral surgery and anteromedial tibial tubercle transfer

Chapter synopsis

In patellofemoral surgery, complex decision-making is common, given the variability of anatomic, structural, psychosocial, and functional factors pertaining to patellofemoral disorders. History and physical examination are always important. Listening closely to the patient is essential regarding the patellofemoral joint, as most patients will lead you directly to logical decisions despite previous misdiagnosis or inaccurate surgery. Only precise radiographs are acceptable in defining patellofemoral structure. One must recognize also that advanced imaging of the patellofemoral joint is typically reviewed in two dimensions such that they do not, in many cases, adequately define structural and functional anomalies that underlie persistent or iatrogenic patellofemoral pain or instability. Three-dimensional imaging and reproductions are increasingly available and invaluable for decision-making regarding complex patellofemoral problems, particularly following complications, failed surgery, or dysplastic anatomy.

Tibial tubercle transfer is often helpful in complex and revision patellofemoral surgery because of the considerable options for altering patellofemoral alignment, balance, and load distribution, often to supplement anatomic retinacular reconstruction. Articular cartilage surgery is appropriate when osteotomy and retinacular reconstruction alone are insufficient.

Important points

• Details of history and physical are very important

• Listen to the patient. He/she will often lead you straight to the problem

• Always watch the patient walk and jump when possible

• All radiographs must be precise

• Always obtain low angle axial radiographs (30 and 45 degrees knee flexion)

• High flexion (sunrise) axial radiographs usually provide little useful information

• Lateral radiographs must have posterior condyles overlapped

• Advanced imaging is helpful but often based on interpretation of two dimensional, non-orthogonal cuts that can be misleading

• Three-dimensional reproductions with hard copy prints of both patella and trochlea are very helpful for complex decision making in patients with dysplasia

• Surgical balancing of patellofemoral tracking by tibial tubercle transfer is often helpful when properly planned in complex situations and will often prevent or delay patellofemoral arthritis

Clinical/surgical pearls

• Optimizing core stability and strength are essential

• Most patients who require surgery will respond favorably to a procedure that optimizes articular contact and balance

• Lateral release or lengthening is appropriate only for documented lateral instability when lateral retinaculum is causing distortion of alignment

• Medial patella instability is almost always iatrogenic—usually found in a patient that had undergone a lateral release procedure. The patient experiences this as very sudden giving way as the patella goes from too far medial, laterally to the central trochlea .

• Anteromedial tibial tubercle transfer is successful for treating most patients with lateral tracking and lateral focal overload. It is a powerful procedure for patellofemoral primary and revision surgery in patients with lateral and distal patella articular lesions

• Patellofemoral joint preservation is the goal in young, active patients. Arthroplasty is rarely needed in young patients, but sometimes is the only remaining option when articular cartilage is severely disrupted

• Prompt rehabilitation and early motion are important hedges against stiffness and pain

• Every complex patellofemoral problem has a logical reason for the pain that you must discover. The patellofemoral joint is not a “black box”

Clinical/surgical pitfalls

• Iatrogenic medial patella subluxation is commonly missed and, as mentioned above, is usually related to excessive lateral release or over-zealous medial tibial tubercle transfer

• A painful result of media patellofemoral ligament (MPFL) reconstruction is often related to medial overload after attempting to alter patella tracking alignment by pulling the patella with a medial tendon graft or repair

• Trochleoplasty may be an appropriate salvage procedure for patients with ligamentous hyperlaxity or a deflecting supratrochlear spur but deprives articular cartilage of nutrition initially and may lead to late patellofemoral arthritis. It is rarely needed

• Excessive distalization of the tibial tubercle can lead to fixation failure in the short term or to patella baja or patellofemoral arthritis in the long term

• Inaccurate imaging can lead to inaccurate diagnosis and inaccurate surgery

• Avoid patellofemoral arthroplasty in younger patients in whom joint preservation is possible

• Considering the patellofemoral joint to be a “black box” is the same as giving up on the patient!