This chapter addresses the surgical technique of a tibial tubercle transfer for the treatment of patellar instability and isolated patellofemoral arthritis.

Causes of patellofemoral joint instability and isolated patellofemoral arthritis are multifactorial and can be related to problems with limb alignment, the osseous architecture of the patella and trochlea, and the integrity of the surrounding soft tissues. The incidence of patellar dislocation is 5.8 per 100,000, and this increases to 29 per 100,000 in the 10 to 17-year old age group. The recurrence rate averages 15% to 44% after nonoperative treatment of an acute injury. If there is a subsequent dislocation after the primary injury, the recurrence rate increases to 50%. Many patients continue to have mechanical symptoms and pain after a patellar dislocation. Atkin et al. reported that up to 55% of patients fail to return to sports activity after a primary patellar dislocation. He also showed that 58% of people have limitations with strenuous activity at 6 months after a primary dislocation.

The operative treatment of patellofemoral arthritis is variable depending on the degree and the location of the chondral damage, the age of the patient, and associated chondral injury to the tibialfemoral joint. Arthroscopic débridement can be used for isolated, superficial chondral flaps in the patellofemoral joint. Anteromedialization of the tibial tubercle can be used for the treatment of isolated lateral patellar facet arthritis. Patellofemoral replacement is used in patients with normal limb alignment and osseous anatomy who have diffuse patellofemoral arthritis. Total knee replacement offers the best clinical results in older patients or patients with associated tibiofemoral arthritis.

Patients with patellofemoral arthritis and recurrent patellar instability have similar symptoms. They may present with a sense of instability, pain, mechanical symptoms, and/or recurrent effusions. Most patients have tried a course of physical therapy to work on flexibility, proprioception, and strengthening around the knee and the hip. Bracing occasionally relieves some of the pain and instability. Hyaluronic acid injections can help relieve some of the swelling, pain, and mechanical symptoms.

A thorough examination of the entire lower limb should be performed and should be compared to the contralateral side. The following findings should be documented: limb rotation (femoral anteversion, external tibial torsion), muscle atrophy, core strength, crepitation, effusion, local or diffuse tenderness, patellar glide, patellar tracking throughout range of motion, patellar tilt, tuberosity position in relation to the center of the trochlea, apprehension (medial and lateral), and the Fulkerson medial instability test.

Tibial tubercle transfer can be done for patellofemoral arthritis or instability. Indications for medialization of the tubercle include symptoms of patellofemoral instability along with an increased TT-TG distance (>20 mm). Indications for anteromedialization of the tibial tubercle include symptoms of patellofemoral instability and pain along with an increased TT-TG distance and/or distal/lateral patellar facet chondrosis or lateral trochlear chondrosis.

Contraindications of tibial tubercle transfer include medial and/or proximal patellofemoral chondrosis that would be subjected to increased loading with a transfer of the tubercle. Standard contraindications to any osteotomy around the knee include osteoporosis, nicotine use, nonspecific pain, complex regional pain syndrome, inflammatory arthropathy, infection, patella baja, or arthrofibrosis.

The type of anesthesia used for the case is decided by the surgeon, patient, and anesthesiologist. Options include general anesthesia, sedation along with local anesthesia, regional nerve blocks, or spinal anesthesia. Nerve blocks, including femoral and sciatic, are very popular at our institution. These can be “one-shot” blocks that provide anesthesia for about 18 hours or an indwelling catheter can be left in place. These catheters are routinely removed 3 days postoperatively and are done to provide sensory but not motor block. A narcotic prescription is sent home with all patients, and prophylactic antibiotics are given before the skin incision but not postoperatively.

The patient is place supine on the operating room table. All bony prominences are well padded. An egg-crate cushion is placed under the nonoperative leg. A tourniquet is applied and is insufflated to 250 mm Hg during the osteotomy portion of the case only.