John P. Fulkerson

Current Concepts Review The Medial Patellofemoral Ligament

Awareness of the medial patellofemoral ligament has increased markedly over the past decade. Previously, this structure, which was delineated in anatomical studies, had been little recognized and underestimated with regard to its importance in stabilizing the patella. The goal of this review of the medial patellofemoral ligament is to develop a current understanding of how this ligament functions in patellofemoral stability and to review the current treatment options for medial patellofemoral ligament disruption.

Diagnosis and Treatment of Patients with Patellofemoral Pain

The patient-athlete with patellofemoral pain requires precise physical examination based on a thorough history. The nature of injury and specific physical findings, including detailed examination of the retinacular structure around the patella, will most accurately pinpoint the specific source of anterior knee pain or instability. Radiographs should include a standard 30° to 45° axial view of the patellae and a precise lateral radiograph. Nonoperative treatment is effective in most patients. Prone quadriceps muscle stretches, balanced strengthening, proprioceptive training, hip external rotator strengthening, patellar taping, orthotic devices, and effective bracing will help most patients avoid surgery. When surgery becomes necessary, indications must be specific. Lateral release is appropriate for patella tilt (abnormal rotation). Painful scar or retinaculum, neuromas, and pathologic plicae may require resection. Proximal patellar realignment may be accomplished using arthroscopic or a combined arthroscopic/mini-open approach. Symptomatic articular lesions and more profound malalignments may require medial or anteromedial tibial tubercle transfer. Clinicians should be particularly alert for symptoms of medial subluxation in postoperative patients and should use the provocative medial subluxation test followed by lateral displacement patellar bracing to confirm a diagnosis of medial patellar subluxation. This problem may be corrected in most patients using a lateral patellar tenodesis. Current thinking emphasizes precise diagnosis, rehabilitation involving the entire kinetic chain, restoration of patella homeostasis, minimal surgical intervention, and precise indications for more definitive corrective surgery.

Anteromedialization of the tibial tuberosity for patellofemoral malalignment.

Anteromedialization of the tibial tuberosity is a new and highly effective technique for transferring the tibial tuberosity when anteriorization is desired in addition to medial shift of the patellar tendon insertion. Prompt primary bone healing can be achieved, allowing rapid rehabilitation with substantially improved patellofemoral mechanics. No bone grafting is necessary to achieve anteriorization, although only slight to moderate anteriorization is possible in most cases. Realignment of the patellofemoral mechanism and relief of patellofemoral contact stress can be achieved in one procedure.

Anteromedial tibial tubercle transfer without bone graft

We followed 30 patients for more than 2 years after anteromedial tibial tubercle transfer for persistent pa tellofemoral pain associated with patellar articular de generation. Twelve of these patients were followed more than 5 years. We report 93% good and excellent results subjectively and 89% good and excellent results objectively. The quality of improvement was sustained in all 12 of the patients who were evaluated again after more than 5 years from surgery. When examined sep arately, 75% of those patients with advanced patellar arthrosis achieved a good result; none of these patients achieved an excellent result. Postoperative continuous passive motion has markedly reduced the incidence of stiffness. Serious complications such as compartment syndrome, infection, and skin slough were avoided completely in 51 consecutive cases. Patellofemoral contact pressure studies in five cadaver knees have shown that anteromedial tibial tubercle transfer can provide substantial reduction of patellofemoral contact stress while helping to balance medial and lateral facet pressures. This surgical procedure is mechanically and clinically successful for alleviating intractable pain re lated to patellar malalignment and articular degenera tion. This procedure enables the majority of appropri ately selected patients with malalignment and patellar articular degeneration to resume increased levels of activity with substantially diminished pain.

Disorders of patellofemoral alignment.

Disorders of patellofemoral alignment. J Fulkerson;K Shea; The Journal of Bone & Joint Surgery

An alternative cruciate reconstruction graft: The central quadriceps tendon

The central quadriceps tendon, above the patella, is thicker and wider than the patella tendon. Using precise technique, one can obtain a tendon graft for cruciate reconstruction with 50% greater mass than a patellar tendon bone-tendon-bone graft of similar width. The central quadriceps tendon graft may be harvested by a second surgeon while the first surgeon is simultaneously accomplishing notch-plasty and tunnel placement for cruciate ligament reconstruction. Consequently, this cruciate ligament reconstruction graft offers time savings as well as greater tendon volume. The central quadriceps tendon graft is difficult to harvest, with significant risk of entering the suprapatellar pouch and losing knee distension during ACL reconstruction. By careful adherence to the technique described in this article, the surgeon can obtain this reconstruction graft safely. It is important to recognize the anatomic subtleties of the proximal patella, which include a curved proximal surface, dense cortical bone, and closely adherent suprapatellar pouch. Proper technique is of utmost importance in obtaining this tendon graft safely and efficiently.

Mechanical Evaluation of a Soft Tissue Interference Screw in Free Tendon Anterior Cruciate Ligament Graft Fixation

In this study of bioabsorbable screw fixation of free tendon grafts used in anterior cruciate ligament reconstruction, we performed load-to-failure and cyclic loading of tendon fixation in porcine bone. Bone density measurements from dual photon absorptometry scans were obtained to correlate bone density with fixation failure. The average density of porcine bone (1.42 g/cm2) was similar to that of young human bone (1.30 g/cm2) and significantly higher than that of elderly human cadaveric bone specimens (0.30 g/cm2). Cyclic loading was performed on free tendon grafts fixed with a bioabsorbable screw alone and on grafts fixed with a bioabsorbable screw and an anchor (polylactic acid ball or cortical bone disk). Stiffness of fixation increased substantially with the addition of a cortical bone disk anchor or polylactic acid ball compared with the interference screw alone. Tensile fixation strength of central quadriceps free tendon and hamstring tendon grafts were significantly superior in porcine bone of density similar to young human bone than in elderly human cadaveric bone. The bioabsorbable interference screw yielded loads at failure comparable with traditional bone-tendon-bone and hamstring tendon fixation when controlled for bone density. The addition of a cortical bone disk anchor provided the most optimal fixation of free tendon with the bioabsorbable screw and reduced slippage with cyclic loading to a very low level.

The Etiology of Patellofemoral Pain in Young, Active Patients: A Prospective Study

In a prospective clinical examination of 78 knees in 60 young patients with patellofemoral pain, pain occurred frequently in the lateral peripatellar retinaculum, sometimes in association with milder, less well defined medial patellar discomfort. Patellofemoral pain in the young person is frequently a soft tissue problem initially, but aberrant mechanics (particularly lateral tracking) that cause this retinacular overuse and pain may eventually lead to synovial irritation and chondromalacia. Chondromalacia, however, may not be the primary cause of patellofemoral pain in many young people.

Anterior knee pain in females.

There are clear differences between men and women regarding anterior knee pain. Anatomic factors including increased pelvic width and resulting excessive lateral thrust on the patella are primary factors that predispose females to anterior knee pain. Effects of estrogen on connective tissue synthesis have been reported, but there is no clear mechanism by which this would affect anterior knee pain. Postural and sociologic factors such as wearing high heels and sitting with legs adducted can influence the incidence and severity of anterior knee pain in women.

The Effect of Kurosaka Screw Divergence on the Holding Strength of Bone-Tendon-Bone Grafts:

Fresh-frozen porcine knees were used to demonstrate the effects of diverging Kurosaka screw placement on linear load to failure in simulated anterior cruciate liga ment reconstructions. Screws, placed anteromedially (rear-entry or tibial type) or intraarticularly (endoscopic femoral type) into each tibia, were directed at 0°, 15°, or 30° divergence angles relative to a guide wire. Grafts were axially loaded to failure to determine holding strength. Hierarchical analysis of variance was used to analyze differences between tibial side and endoscopic femoral type screw placement and the angles of diver gence. Overall, the difference in pullout strength be tween rear-entry (or tibial side) and endoscopic femoral type fixation was shown to be statistically significant (P < 0.001). Anteromedially placed screws showed a sta tistically significant decrease in holding strength at 15° and 30° compared with 0° of divergence (P < 0.05). Intraarticular screw placement resulted in a statistically significant decrease in holding strength only at 30° of divergence (P < 0.05). This study supports the impor tance of accurate screw placement within the tibia to ensure optimal interference fixation and suggests that endoscopic screw placement may offer significant added security when there are minor degrees of divergence.