This study assessed medial patellofemoral ligament reconstruction using a partial-thickness quadriceps tendon graft in 14 knees in 13 patients. Nine patients were available for follow-up after a minimum of 24 months. Final patient evaluation was performed an average of 42 months postoperatively (range, 28-65 months). Primary outcome measure was occurrence of patellar dislocation postoperatively, and outcomes were quantified using the Kujala questionnaire and Crosby and Insall criteria. Postoperatively, no patient reported patellar dislocation. Using Crosby and Insall criteria, good or excellent results were achieved in 100% of patients. Mean Kujala score was 91.9. Postoperatively, all patients reported their knee was improved. These findings indicate medial patellofemoral ligament reconstruction with a quadriceps tendon graft is effective in preventing patellar dislocation and improving quality of life. However, patients should be counseled this procedure is indicated primarily for the treatment of recurrent instability, and postoperative relief of anterior knee pain is inconsistent. Level of Evidence: Level IV, Case Series.
Numerous surgical procedures have been described for the treatment of recurrent patellar dislocation. These procedures include various techniques of proximal realignment, distal realignment, combined realignment, and lateral retinacular release.
Proximal realignment tightens the structures of the medial aspect of the knee. However, it does not specifically address the injury to the medial patellofemoral ligament, which is the primary pathoanatomy associated with lateral patellar dislocation.1-3 Distal realignment is appropriate for the treatment of symptomatic patients with an abnormal quadriceps angle, but isolated distal realignment is not indicated in patients with recurrent instability and a normal quadriceps angle. Lateral retinacular release is appropriate for the treatment of pathologic lateral patellar tilt when associated with anterior knee pain. However, isolated lateral retinacular release for the treatment of recurrent patellar dislocation may lead to persistent instability in up to 40% of patients.4,5
In recent years, increasing emphasis has been placed on the importance of the medial patellofemoral ligament as the primary static soft-tissue restraint to lateral patellar translation.6-9 Several authors4,10-16 have developed techniques of medial patellofemoral ligament reconstruction for patients with recurrent patellar dislocation and have reported good preliminary results. These techniques have used various grafts for reconstruction, including hamstring tendons, adductor magnus tendon, quadriceps tendon-bone, iliotibial band, and medial patellar retinacular tissue as well as synthetic grafts.
This case series examined whether medial patellofemoral ligament reconstruction with a partial-thickness quadriceps tendon graft for recurrent patellar dislocation would prevent further episodes of dislocation and improve patients activity levels and quality of life.
Materials and Methods
The senior author (R.S.) performed medial patellofemoral ligament reconstruction in 14 knees (13 patients) for recurrent patellar instability. Nine patients were available for follow-up after a minimum of 24 months; attempts to contact the remaining 4 patients by phone and mail were unsuccessful. The medical records of these 4 patients were reviewed and their postoperative recovery was noted to be unremarkable, with no postoperative episodes of instability or complications at last follow-up.
Medial patellofemoral ligament reconstruction was performed using an autogenous partial-thickness quadriceps tendon graft in all cases. Reconstruction was performed in conjunction with other procedures when indicated, based on physical examination and intraoperative findings (Table 1).
All patients underwent a detailed history, physical examination, and radiographic examination preoperatively. Five patients were women and 4 patients were men. Five left knees and 4 right knees were included in the study.
Mean age at first patellar dislocation was 16.7 years (range, 3-30 years). In all 9 patients, the initial dislocation was associated with a traumatic event (Table 2). Mean age at surgery was 26.1 years (range, 15-46 years). Mean follow-up was 42 months (range, 28-65 months).
Mean number of preoperative dislocations was 28.6 (range, 1-100). Five patients had undergone surgery on the operative knee prior to medial patellofemoral ligament reconstruction (Table 3).
Three of the nine patients (33%) reported frequent pain associated with the recurrent instability. Two of these patients reported pain on a daily basis, and the third patient reported pain at least once per week. Pain was infrequent for the remaining 67% of patients.
Preoperatively, 8 of the 9 patients (89%) experienced persistent disability with athletics. The remaining patient had never been involved with athletics, either before or after the initial injury. Seventy-eight percent of patients reported disability with ascending or descending stairs. Sixty-seven percent of patients reported disability with activities of daily living and in the workplace.
The chief complaint that led to seeking surgical intervention was recurrent dislocation or subluxation in 8 patients (89%). Of these 8 patients, 4 patients had additional complaints, including pain (2), swelling (1), and weakness (1). One patient had a solitary chief complaint of recurrent effusion (11%).
Intraoperatively, some degree of chondromalacia involving the patellofemoral articulation was noted in 89% of patients. In addition to the medial patellofemoral ligament reconstruction, 78% of patients underwent additional procedures (Table 1). In 4 patients, the reconstruction was augmented by a medial capsular imbrication, as described by Steensen et al.17 Additional procedures included patellofemoral chondroplasty (4 patients), lateral release (3 patients), tibial tubercle osteotomy (1 patient), partial lateral meniscectomy (1 patient), and synovial debridement (1 patient). There were no intraoperative complications.
The surgical technique has been described previously by Steensen et al.18 A thorough examination under anesthesia was performed first to confirm the ability to dislocate the patella laterally and assess whether the lateral retinaculum required release.
A tourniquet was applied to the thigh, and routine arthroscopy was performed, with specific attention to the articular surfaces of the patellofemoral joint. Chondral injuries were documented, and unstable flaps were debrided. Any loose bodies were removed, and if indicated, a lateral release was performed.
Next, a longitudinal incision was made from the superior pole of the patella extending approximately 5 cm proximally (Figure 1). The quadriceps tendon was identified, using knee flexion to enhance proximal visualization.
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Figure 1: The graft is harvested through a longitudinal midline incision starting at the superior pole of the patella and extending 5 cm proximally. Femoral fixation is achieved through a 2-cm incision placed over the medial epicondyle. Figure 2: A partial-thickness graft is harvested from the central third of the quadriceps tendon, leaving its attachment to the patella intact. Dissection is extended further distally on the lateral aspect of the graft.
A partial-thickness graft was harvested from the quadriceps tendon, leaving its attachment to the patella intact. The graft was approximately 10 to 12 mm in width and typically involved the central one-third of the tendon, although this was shifted slightly medially if necessary. The graft was taken from the most superficial layer of the quadriceps tendon, which is a trilaminar structure.
Using sharp dissection, harvesting of the graft began approximately 2 to 3 cm above the patella, and dissection was extended both proximally and distally. Care was taken not to amputate the graft distally at its patellar attachment where the trilaminar nature of the tendon is less discernible.
The length of graft necessary for reconstruction of the ligament was estimated by measuring the distance from the superior pole of the patella to the medial epicondyle of the femur. The dissection was extended proximally as needed to assure the graft was of sufficient length to reach the medial epicondyle, and the graft then was cut proximally. If the proximal end of the graft was beyond the superior extent of the exposure, it was transected through a small stab incision placed proximally.
Sharp dissection was continued distally to the patella, with care taken to maintain adequate thickness of the graft in this location. The dissection was extended further distally on the lateral aspect of the graft (Figure 2).
A 2-cm incision was made over the palpable prominence of the medial femoral epicondyle (Figure 1). The epicondyle was exposed, and a subcutaneous tunnel was created between the 2 incisions using blunt dissection. A K-wire was drilled into the most prominent portion of the epicondyle.
The quadriceps graft then was turned 90° medially and twisted 180° (Figure 3). Because additional distal dissection was performed on the lateral side of the graft at its patellar attachment, the graft was able to lie flush at this location after this maneuver. This created a 45° angle at the site where the graft was folded, although the graft itself was positioned 90° from its original site of harvest. In addition, the deep surface of the graft became oriented as the superficial surface. The free proximal end of the graft then was delivered to the medial incision through the subcutaneous tunnel (Figure 4).
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Figure 3: The quadriceps graft is turned medially 90° and twisted 180°. Figure 4: The free proximal end of the graft is passed through the subcutaneous tunnel to the medial incision, forming a 45° angle at the site where the graft was folded. The graft is positioned 90° from its original harvest site, and the deep surface of the graft is oriented as the superficial surface. Femoral fi xation is attained with sutures through bone tunnels at the medial epicondyle. Two passes are made through the bone, resulting in 4 holes outlining a 1 cm2 area that is roughly square in configuration.
The free end of the graft was grasped with a clamp or sutures. The graft was tensioned over the K-wire with the knee in mid-flexion while the patella was manually compressed into the trochlea. A surgical marker was used to draw a line on the graft at the point where it crossed the K-wire.
The knee then was taken through a range of motion while the relationship between the line on the graft and the K-wire was observed. If there was <2 to 3 mm of movement of the line relative to the K-wire, graft placement was considered relatively isometric, and the location of the K-wire served as the femoral attachment site for the graft. If there was considerable movement of the line on the graft relative to the K-wire, another femoral attachment site was trialed.
After the femoral attachment site was determined, sutures through bone tunnels typically were used for fixation. In most cases, 2 passes were made through the bone using a CurvTek drill (Arthrotek, Warsaw, Indiana). This resulted in 4 holes outlining a 1 cm2 area that was roughly square in configuration (Figure 4). Two zero-nonabsorbable sutures then were threaded through the holes, resulting in 4 strands of suture at the desired attachment site on the medial epicondyle.
The knee then was placed in mid-flexion, and the patella was manually compressed into the trochlea. Gentle tension was applied to the quadriceps graft while the sutures were passed through the graft and tied, firmly securing the graft to the bone.
Patellar tracking was assessed through a range of motion. The amount of lateral patellar excursion allowed by the reconstruction also was assessed at this time. Lateral patellar dislocation was no longer possible if adequate medial restraint was restored. It was equally important that the patella not be overly constrained, as this could lead to medial patellar subluxation or graft failure.
Any extra length of graft at the medial epicondyle was folded back on itself and sutured (Figure 5). At the site of patellar attachment, the superior and inferior margins of the graft were sutured to the anterior patellar retinaculum. The defect in the quadriceps was partial thickness and was not closed. After completion of the reconstruction, routine wound closure was performed.
Figure 5: After the graft has been sutured to the medial epicondyle, any extra length of graft is folded back on itself and sutured.
Postoperatively, patients were placed in a knee immobilizer and were encouraged to bear weight as tolerated. The knee immobilizer was removed several times daily to work on knee range of motion with patients seated and nonweight bearing. Quadriceps sets and straight-leg raises were begun as soon as possible. The knee immobilizer was discontinued after patients demonstrated good quadriceps control.
This technique for medial patellofemoral ligament reconstruction was combined with lateral retinacular release, medial capsular imbrication, and distal realignment when clinically indicated. Medial patellofemoral ligament reconstruction was performed after completion of any other procedures, which allowed for the reconstructed ligament to be optimally tensioned.
Follow-up assessment consisting of a detailed history and physical examination was performed in all patients an average of 42 months (range, 28-65 months) postoperatively. The primary outcome measure was whether patients experienced patellar dislocation postoperatively. Additionally, patients were asked if they experienced subjective improvement in athletic participation and activities of daily living as a result of the procedure. Patient satisfaction also was directly assessed.
Two different knee rating systems were used to assess outcomes. Patients were evaluated using both Crosby and Insall criteria19 and the Kujala questionnaire.20 Any postoperative complications or further surgical procedures were noted.
No patient experienced postoperative patellar dislocation. One patient experienced a single episode of painful patellar subluxation that occurred as he was climbing onto a dock while swimming.
Seven patients (78%) reported pain was infrequent postoperatively. Three patients had reported pain preoperatively, and 2 of these patients reported persistent pain postoperatively. Both patients with complaints of postoperative anterior knee pain reported at least 50 episodes of patellar dislocation preoperatively.
Patients were asked whether their chief complaint was corrected by surgery and were given the following potential responses: not at all corrected, partially corrected, mostly corrected, or completely corrected. Four patients stated their problem was completely corrected by surgery, 4 patients responded mostly corrected, and 1 patient responded partially corrected. No patient responded not at all corrected.
Patients also were asked to rate their satisfaction with the surgery as: not at all satisfied, moderately satisfied, very satisfied, or completely satisfied. Six patients responded they were completely satisfied, 2 patients responded very satisfied, and 1 patient responded moderately satisfied. No patient responded not at all satisfied.
Seven patients (78%) reported their ability to participate in athletic activity had improved postoperatively. Two patients (22%) reported their ability to participate in athletics had not improved postoperatively; however, this was not due to persistent instability: 1 patient reported persistent anterior knee pain and the second patient reported persistent swelling. All of the patients stated the overall condition of their knee was improved as a result of the surgery.
Outcomes were measured according to the criteria of Insall and Crosby19 (Table 4). Good outcomes were achieved in 56% of patients, and excellent outcomes were achieved in 44% of patients. No outcomes were classified as fair to poor or worse. Mean postoperative Kujala score20 was 91.9 (range, 77-100).
On physical examination, 100% of patients had full range of motion compared to the contralateral knee. No patient had excessive lateral patellar translation or patellar apprehension, and no patient had excessively tight lateral retinacular structures. Five patients (56%) had slight or moderate patellofemoral crepitation that was painless, and 1 patient (11%) had moderate to severe crepitation that was painful.
In 89% of patients, there was no evidence of quadriceps atrophy. Mild quadriceps atrophy was present in 1 patient. In 44% of patients, a J sign was present in terminal extension; this was asymptomatic in all instances.
One patient experienced a postoperative wound infection that required incision and drainage in the operating room. The infection ultimately resolved without further complication. Another patient developed a small superficial wound hematoma postoperatively. This was debrided in the office and resolved uneventfully. There were no other complications or additional surgical procedures postoperatively.
The medial patellofemoral ligament is a structure located in the second layer of the medial aspect of the knee. The ligament originates from the medial epicondyle of the femur and the adductor tubercle. Its fibers run in a transverse direction to insert primarily on the superomedial aspect of the patella (Figure 6).6,7,21-25 The length of the medial patellofemoral ligament is approximately 53 to 58 mm,23,24 and the width is approximately 13 to 19 mm, with the ligament being consistently thicker at its patellar insertion than at its femoral origin.6,23-25 The medial patellofemoral ligament is the primary static soft-tissue restraint to lateral patellar translation, providing between 53% and 60% of the total medial restraining force.6,7
Sectioning of the ligament in cadaveric knees has significantly altered patellar tracking, with subsequent repair or reconstruction of the ligament restoring patellar tracking toward normal.8,9 Studies entailing surgical exploration in patients after acute patellar dislocation have established the medial patellofemoral ligament is disrupted during acute patellar dislocation in the majority of patients.1-3
Because the medial patellofemoral ligament is functionally incompetent in the majority of patients with recurrent patellar dislocation, we believe formal reconstruction of the ligament is preferable to isolated medial reefing or other techniques of proximal realignment. Many techniques of medial patellofemoral ligament reconstruction have been described,4,10-16 and preliminary results have been encouraging. However, there has been no comparison between different techniques; therefore, the ideal graft and technique for reconstruction are as yet undetermined.
Our technique offers several theoretical advantages over other techniques. Both Ellera Gomes10 and Nomura et al15 have advocated medial patellofemoral ligament reconstruction with artificial ligaments. Although an artificial ligament may provide adequate initial stability, it does not possess the ability to undergo biological remodeling, as does an autogenous graft. Therefore, its long-term efficacy is unknown.
Use of a quadriceps tendon graft for medial patellofemoral ligament reconstruction has been described by Burks and Luker.13 Their technique entails harvest of a free graft that includes a portion of the quadriceps tendon, as well as an attached patellar bone block. One of the advantages of our technique is that it makes use of a graft that is purely tendinous and does not include a patellar bone block. This eliminates the risks of patellar fracture and violation of the patellar articular surface.
Figure 6: Anatomy of the medial aspect of the knee. (Reprinted with permission from Steensen RN, Dopirak RM, McDonald WG III. The anatomy and isometry of the medial patellofemoral ligament: implications for reconstruction. Am J Sports Med. 2004; 32(6):1509-1513. Copyright © 2005. The American Orthopaedic Society for Sports Medicine.)
With our harvesting technique, the graft is detached proximally but remains attached distally. This serves to simplify the procedure as the surgeon is required to free and then secure only one side of a graft. Furthermore, the preserved insertion of the graft on the patella is near the normal patellar attachment of the medial patellofemoral ligament. Reproducing the anatomy of the native medial patellofemoral ligament enables the reconstructed ligament to function isometrically, thus maximizing its efficacy through the full range of motion. This allows for early range of motion postoperatively.
Several anatomic factors should be considered during harvesting of the quadriceps tendon graft with our technique. The quadriceps tendon is a trilaminar structure. The anterior layer is formed by the rectus femoris, the middle layer is formed by the vastus medialis and lateralis, and the deep layer is formed by the vastus intermedius. The quadriceps tendon inserts distally into the patella via an expansion that passes over the anterior aspect of the patella. Most commonly, this distal expansion is comprised solely of fibers from the rectus femoris portion of the tendon.26-29
In our technique, the graft is harvested solely from the anterior lamina of the quadriceps tendon, which is the rectus femoris tendon. The average thickness of the rectus femoris tendon is 3.4 mm29; this should be kept in mind during graft harvest. We have found the interval between the anterior and middle laminae of the quadriceps tendon is most easily identified proximal to the patella. Thus, graft harvest should begin a few centimeters proximal to the patella.
More distally, where the rectus tendon inserts into the anterior aspect of the patella, the surgical plane may be more difficult to follow. The insertion of the quadriceps tendon into the patella typically consists of the rectus femoris alone.26-29 Subperiosteal dissection should be used in this area to maintain a graft of adequate thickness. The average length of the rectus femoris tendon is 79 mm,29 whereas the average length of the native medial patellofemoral ligament is approximately 53 to 58 mm.23,24 Thus, this graft source typically should be of adequate length to reconstruct the medial patellofemoral ligament.
The outcomes criteria of Crosby and Insall19 were used because this rating system was designed specifically to assess patients with recurrent patellar dislocation. Furthermore, it is focused on patellar stability and the patients subjective assessment of outcomes. Use of this rating system enabled us to assess our 2 primary goals, which were to restore stability to the patellofemoral articulation and improve patients activity level and quality of life.
The Crosby and Insall criteria have been used to assess outcomes in many other studies as well. In their original study,19 only 65% of patients reported good or excellent results after nonoperative treatment of patellar dislocation.
Ellera Gomes10 reconstructed the medial patellofemoral ligament with an artificial ligament in 30 patients with recurrent dislocation. Good or excellent results were obtained in 83% of their patients. In a more recent study, Ellera Gomes et al11 used a semitendinosus graft to reconstruct the medial patellofemoral ligament in 16 knees with chronic patellar instability. Good or excellent results were obtained in 94% of knees.
Nomura et al15 performed medial patellofemoral ligament reconstruction in 27 knees with recurrent patellar dislocation with a mesh-type artificial ligament and medial retinacular slip. Ninety-six percent of knees were classified as good or excellent. Our results compare favorably with these other series, with 100% of our patients reporting good or excellent outcomes.
We also used the Kujala questionnaire20 to assess patient outcomes. This questionnaire is a detailed subjective assessment that is specific for patellofemoral disorders. Additionally, use of this questionnaire enabled us to compare our outcomes to other studies evaluating cohorts of patients with patellofemoral disorders. In their study of 100 patients treated nonoperatively after primary patellar dislocation, Maenpaa and Lehto30 reported the mean Kujala score for these patients was 80.
Ahmad et al31 performed immediate surgical repair of the medial stabilizers after acute patellar dislocation in 8 patients; mean Kujala score at a minimum follow-up of 1.5 years was 91.9. Drez et al4 performed medial patellofemoral ligament repair or reconstruction in 15 patients; mean Kujala score was 88 at 31.5 months of follow-up. Our results compare favorably with these series; the mean Kujala score for our patients was 91.9.
Medial patellofemoral ligament reconstruction with a partial-thickness quadriceps tendon graft is a simple procedure with little associated morbidity. In patients with recurrent patellar instability, medial patellofemoral ligament reconstruction with a quadriceps tendon graft is effective in preventing further episodes of patellar dislocation and improving quality of life. However, patients should be counseled this procedure is indicated primarily for the treatment of recurrent instability, and postoperative relief of anterior knee pain is inconsistent.
- Sallay PI, Poggi J, Speer KP, Garrett WE. Acute dislocation of the patella: a correlative pathoanatomic study. Am J Sports Med. 1996; 24(1):52-60.
- Sanders TG, Morrison WB, Singleton BA, Miller MD, Cornum KG. Medial patellofemoral ligament injury following acute transient dislocation of the patella: MR findings with surgical correlation in 14 patients. J Comput Assist Tomogr. 2001; 25(6):957-962.
- Nomura E, Horiuchi Y, Inoue M. Correlation of MR imaging findings and open exploration of medial patellofemoral ligament injuries in acute patellar dislocations. Knee. 2002; 9(2):139-143.
- Drez D Jr, Edwards TB, Williams CS. Results of medial patellofemoral ligament reconstruction in the treatment of patellar dislocation. Arthroscopy. 2001; 17(3):298-306.
- Aglietti P, Buzzi R, De Biase P, Giron F. Surgical treatment of recurrent dislocation of the patella. Clin Orthop Relat Res. 1994; (308):8-17.
- Conlan T, Garth WP Jr, Lemons JE. Evaluation of the medial soft-tissue restraints of the extensor mechanism of the knee. J Bone Joint Surg Am. 1993; 75(5):682-693.
- Desio SM, Burks RT, Bachus KN. Soft tissue restraints to lateral patellar translation in the human knee. Am J Sports Med. 1998; 26(1):59-65.
- Hautamaa PV, Fithian DC, Kaufman KR, Daniel DM, Pohlmeyer AM. Medial soft tissue restraints in lateral patellar instability and repair. Clin Orthop Relat Res. 1998; (349):174-182.
- Sandmeier RH, Burks RT, Bachus KN, Billings A. The effect of reconstruction of the medial patellofemoral ligament on patellar tracking. Am J Sports Med. 2000; 28(3):345-349.
- Ellera Gomes JL. Medial patellofemoral ligament reconstruction for recurrent dislocation of the patella: a preliminary report. Arthroscopy. 1992; 8(3):335-340.
- Ellera Gomes JL, Stigler Marczyk LR, Cesar de Cesar PC, Jungblut CF. Medial patellofemoral ligament reconstruction with semitendinosus autograft for chronic patellar instability: a follow-up study. Arthroscopy. 2004; 20(2):147-151.
- Avikainen VJ, Nikku RK, Seppanen-Lehmonen TK. Adductor magnus tenodesis for patellar dislocation: technique and preliminary results. Clin Orthop Relat Res. 1993; (297):12-16.
- Burks RT, Luker MG. Medial patellofemoral ligament reconstruction. Techniques in Orthopaedics. 1997; 12(3):185-191.
- Muneta T, Sekiya I, Tsuchiya M, Shinomiya K. A technique for reconstruction of the medial patellofemoral ligament. Clin Orthop Relat Res. 1999; (359):151-155.
- Nomura E, Horiuchi Y, Kihara M. A mid-term follow-up of medial patellofemoral ligament reconstruction using an artificial ligament for recurrent patellar dislocation. Knee. 2000; 7(4):211-215.
- Fithian DC, Meier SW. The case for advancement and repair of the medial patellofemoral ligament in patients with recurrent patellar instability. Operative Techniques in Sports Medicine. 1999; 7(2):81-89.
- Steensen RN, Dopirak RM, Maurus PB. Minimally invasive crescentic imbrication of the medial patellofemoral ligament for chronic patellar subluxation. Arthroscopy. 2005; 21(3):371-375.
- Steensen RN, Dopirak RM, Maurus PB. A simple technique for reconstruction of the medial patellofemoral ligament using a quadriceps tendon graft. Arthroscopy. 2005; 21(3):365-370.
- Crosby EB, Insall J. Recurrent dislocation of the patella: relation of treatment to osteoarthritis. J Bone Joint Surg Am. 1976; 58(1):9-13.
- Kujala UM, Jaakkola LH, Koskinen SK, Taimela S, Hurme M, Nelimarkka O. Scoring of patellofemoral disorders. Arthroscopy. 1993; 9(2):159-163.
- Warren LF, Marshall JL. The supporting structures and layers on the medial side of the knee: an anatomical analysis. J Bone Joint Surg Am. 1979; 61(1):56-62.
- Feller JA, Feagin JA Jr, Garrett WE Jr. The medial patellofemoral ligament revisited: an anatomical study. Knee Surg Sports Traumatol Arthrosc. 1993; 1(3-4):184-186.
- Tuxoe JI, Teir M, Winge S, Nielsen PL. The medial patellofemoral ligament: a dissection study. Knee Surg Sports Traumatol Arthrosc. 2002; 10(3):138-140.
- Smirk C, Morris H. The anatomy and reconstruction of the medial patellofemoral ligament. Knee. 2003; 10(3):221-227.
- Steensen RN, Dopirak RM, McDonald WG III. The anatomy and isometry of the medial patellofemoral ligament: implications for reconstruction. Am J Sports Med. 2004; 32(6):1509-1513.
- Last RJ. Some anatomic details of the knee joint. J Bone Joint Surg. 1948; 30:683-688.
- Reider B, Marshall JL, Koslin B, Ring B, Girgis FG. The anterior aspect of the knee joint. J Bone Joint Surg Am. 1981; 63(3):351-356.
- Clarke HD, Scott WN, Insall JH, et al. Anatomy of the knee. In: Insall JN, Scott WN, eds. Surgery of the Knee. 3rd ed. Philadelphia, PA: Churchill Livingstone; 2001:13-76.
- Harris NL, Smith DA, Lamoreaux L, Purnell M. Central quadriceps tendon for anterior cruciate ligament reconstruction, I: morphometric and biomechanical evaluation. Am J Sports Med. 1997; 25(1):23-28.
- Maenpaa H, Lehto MU. Patellar dislocation: the long-term results of nonoperative management in 100 patients. Am J Sports Med. 1997; 25(2):213-217.
- Ahmad CS, Stein BE, Matuz D, Henry JH. Immediate surgical repair of the medial patellar stabilizers for acute patellar dislocation: a review of eight cases. Am J Sports Med. 2000; 28(6):804-810.
Dr Dopirak is from Lakeshore Orthopedics, Manitowoc, Wisconsin; and Drs Adamany, Bickel, and Steensen are from the Mount Carmel Health System, Columbus, Ohio.
Drs Dopirak, Adamany, Bickel, and Steensen have no relevant financial relationships to disclose.
Correspondence should be addressed to: Ryan Dopirak, MD, Lakeshore Orthopedics, 1650 S 41st St, Manitowoc, WI 54220.