Techniques of medial retinacular repair and reconstruction

The anatomy of the medial patellofemoral ligament

BACKGROUND

Fibrous connections and fibrofatty tissue between the layers of the medial retinaculum have prevented accurate definition of the true anatomy of the medial patellofemoral ligament. This has led to confusion about the origin, form, course, and insertion of this structure.

HYPOTHESIS

The medial patellofemoral ligament is a discrete structure that can be approached, isolated, and definitively described.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Fifty fresh or fresh-frozen human knee specimens were carefully dissected to determine the precise anatomy of the medial patellofemoral ligament.

RESULTS

Present in all specimens, the medial patellofemoral ligament was found to have 2 origins: (1) a transverse 10.6-mm origin from the bony groove between the medial epicondyle and the adductor tubercle, and (2) an oblique decussation originating from the proximal 30 mm of the leading edge of the superficial medial collateral ligament. The 2 origins combined and inseparably joined the vastus medialis obliquus tendon and inserted securely into the ventral edge of the bony patella over a span of 28.2 + or - 5.6 mm adjacent to the articular surface of the patella. The length from the femoral origin to the patella was 59.8 + or - 4.8 mm. The key to the dissection was finding the fine capsular vessels from the descending genicular artery that is between layers I and II of the medial retinacular structures.

CONCLUSION

The medial patellofemoral ligament is a constant structure in ladouble daggeryer II, with a complex anatomy that can be defined by careful dissection using the capsular branches of the descending genicular artery as a guide.

CLINICAL RELEVANCE

This study provides essential new information that could help surgeons safely locate the medial patellofemoral ligament and repair or reconstruct it anatomically.

Length change patterns of the extensor retinaculum and the effect of total knee replacement

Patellofemoral dysfunction following total knee replacement (TKR) is a significant clinical problem, but little information exists on the mechanics of the patellofemoral retinacula or the effects of TKR on these structures. We hypothesized that TKR would cause significant elongation of the retinacula. Retinacular length changes were measured by threading sutures along the retinacula, fixing the sutures to the patella and the iliotibial band (ITB), and attaching the femoral ends to displacement transducers. The intact knee was flexed-extended while the quadriceps and ITB were tensed and the retinacular length change patterns were recorded. The measurements were repeated post-TKR. The medial patellofemoral ligament (MPFL) was close to isometric, stretching 2 mm in terminal knee extension, whereas the lateral retinaculum slackened 8 mm from 110 degrees to 0 degrees flexion. TKR did not cause significant elongation of either of the retinacula, the largest change being 3 mm elongation of the MPFL around 40 degrees , which stretched the MPFL by 1.4 mm above its maximum natural length. Thus, this work did not support the hypothesis that TKR causes significant elongation of the retinacula sufficient to affect knee function.

Management of overtight medial patellofemoral ligament reconstruction

The clinical presentation of an overtight medial patellofemoral ligament (MPFL) reconstruction can differ depending on whether it is too tight in extension (extensor lag) or too tight in flexion (anterior knee pain and loss of flexion). We report one clinical case of each presentation. Both cases were treated with a percutaneous release of the graft. After the release, both patients regained a full active range of motion without residual symptoms. These complications demonstrate that the adjustment of the graft tensioning as well as its femoral position are critical steps in MPFL reconstruction. This procedure requires training and experience in order to avoid early complications related to malposition or inappropriate tensioning of the graft. A surgical management for these overtight reconstructions is recommended, as it will restore function and range of motion, and prevent late patellofemoral degeneration.

Using an iliotibial tract for patellar dislocation in children

OBJECTIVE

To evaluate the clinical and functional results of surgical treatment of patellar dislocation in children.

MATERIAL AND METHODS

A prospective study was undertaken from January 1995 to December 2004. Patients who suffered from patellar dislocation after receiving intramuscular antibiotic injections to quadriceps were recruited. A complete history of each patient was recorded, and both a clinical and a roentgenographic examination were performed preoperatively. Patellar dislocation was classified according to Bensahel's criteria. The iliotibial tract and lateral retinacula was released to restore the tension of the medial retinaculum. Quadricepsplasty was used in all patients for full flexion of knee.

RESULTS

There were nine males and 65 females in this study. All 74 patients (76 knees) developed dislocation of the patella after repeated intramuscular injections of antibiotic(s) into the quadriceps muscle. Fifty-six knees (73.7%) were type 1, and 20 knees (26.3%) were type 2 (Bensahel's classification). In all, we attained excellent results in 56 knees (73.7%), good results in 17 knees (22.4%), and fair results in three knees (3.9%). There have been no poor results or recurrences so far.

CONCLUSION

Use of the iliotibial tract, adequate lateral retinacular release, restoration of the tension of the medial retinaculum and associated quadricepsplasty achieved a high success rate. The technique is simple, safe and effective in skeletally immature children.

Comparison between a static and a dynamic technique for medial patellofemoral ligament reconstruction

PURPOSE

The purpose of our study was to compare the technical difficulties and the results of the use of two different types of femoral graft fixation for medial patellofemoral ligament reconstruction in patients with patellar luxation.

METHODS

Twenty-four matched pair patients, assigned to two groups of 12 patients each, underwent medial patellofemoral ligament reconstruction using one of two techniques: the adductor magnus rigid and the semitendinosus tendon dynamic femoral fixation. Results were assessed using a scale for activities of daily living before and after surgery.

RESULTS

No statistical difference was detected between the groups despite one case of reluxation in the adductor magnus group. No major complication was observed in either group. Patients in the semitendinosus group felt subjectively better, and a larger number of patients in this group resumed the practice of sports.

CONCLUSIONS

Even in the absence of significant differences, the present results suggest that a more dynamic femoral fixation is more advantageous than a rigid alternative.

LEVEL OF EVIDENCE

Level III, therapeutic comparative study.

Reconstruction of the medial patellofemoral ligament with gracilis tendon autograft in transverse patellar drill holes

PURPOSE

We present clinical results in a case series of 44 patients with medial patellofemoral ligament (MPFL) reconstruction with 12 to 32 months' follow-up.

METHODS

Reconstruction was performed via gracilis tendon autograft looped through 2 transverse 4.5-mm drill holes in the patella and fixed at the natural MPFL insertion site on the medial femoral condyle with an interference screw. At follow-up, Kujala scores, Knee Injury and Osteoarthritis Outcome Scores, objective knee function, complications, and reoperations were assessed.

RESULTS

Only 1 patella redislocation was observed. Subluxation occurred in 3 patients, whereas 4 patients had chronic pain at follow-up, all of whom had cartilage injury at surgery. The Kujala knee function score improved overall from 46 points (range, 12 to 67 points) to 84 points (range, 62 to 100 points) at follow-up.

CONCLUSIONS

MPFL reconstruction with double transverse patella drill holes and a gracilis tendon graft provides good postoperative patellar stability. Postoperative pain seems to be related to the degree of patellofemoral injury found at surgery.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Recurrent patellar dislocation after medial patellofemoral ligament reconstruction

We report on three cases of recurrent lateral patellar dislocation following a medial patellofemoral ligament (MPFL) reconstruction for patellar instability. In all three cases, an isolated MPFL reconstruction was performed with a double autogenous gracilis graft. The patellar fixation was done through bone tunnels. All three patients presented with a definite moderate to severe traumatic episode resulting in a recurrent patella dislocation and a transverse avulsion fracture at the medial rim of the patella. All three were treated by an open reduction and internal fixation with good results. No complication or recurrent dislocations occurred. We suggest that this complication is caused by the original underlying pathology such as dysplastic trochlea, abnormal TT-TG, patella alta and hyperlaxity, resulting a greater reliance upon the reconstructed MPFL for patellar stability. When subjected to a severe stress, the graft, which is stronger and stiffer than the original MPFL, will cause a fracture through the medial edge of the patella. This weak area results from the previous drill holes, which act as stress risers.

Patellar tendon shortening after treatment of patellar instability with a patellar tendon medialization procedure

Patellar instability is a multifactorial disorder. Patella alta is strongly associated with patellar instability. We hypothesize that procedures of the patellar tendon such as medialization may shorten the patellar tendon. In this retrospective study, 41 patients with patellar instability were treated operatively with a patellar tendon medialization procedure. Twenty-eight knees were treated using a modified Roux-Goldthwait method and 16 using a modified Elmslie-Trillat method. The patients were followed 2-7 years after the operation. Pre- and post-operative x-rays were analyzed with particular emphasis on patellar tendon length, patellofemoral congruence angle and osteoarthritis. The final clinical outcome was assessed using the Lysholm score and clinical examination. In both groups patients were generally satisfied with the result of the operation and there was no significant difference in Lysholm scores at follow-up. However, patellofemoral osteoarthritic changes increased in both groups compared with the pre-operative status. The patellar tendon length was reduced in both groups, but significantly, by 7%, in the Roux-Goldthwait group. We conclude that patellar tendon shortens after a Roux-Goldthwait procedure.

The favourable anisometry: an original concept for medial patellofemoral ligament reconstruction

Medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar dislocation has recently become more popular. We describe a technique that involves tensioning of the graft with the knee in full extension while simultaneously pulling with a bone hook on the patella in the direction of the quadriceps tendon, thus facilitating placement of the femoral attachment and accurate graft tensioning. We investigated the clinical outcome of this reconstructive procedure in 20 patients (23 knees), with a mean follow-up of 2 years. There was no recurrence of dislocation after surgery. At the 3 months follow up visit, nine knees had an extensor lag. At the last follow up visit, only one patient had an extensor lag. The mean Kujala score at the last follow-up was 93 (+/- 6) points. Severe primary chondral lesion had a negative influence on the final functional result. It is suggested that patella alta could increase the risk of post-operative extensor lag and quadriceps weakness as the tension tends to be more in the reconstructed MPFL than in the patellar tendon when the knee extends. In cases of severe patella alta we would suggest including distalisation of the tibial tubercle, with an MPFL reconstruction.

Combined proximal and distal realignment procedures to treat the habitual dislocation of the patella in adults

BACKGROUND

Habitual dislocation of the patella (HDP) is a rare condition. Many surgical procedures using proximal realignment have been reported to treat HDP in children, with around 80% satisfactory results. However, few articles have addressed the treatment of HDP associated with high-grade patellofemoral chondromalacia in adults.

HYPOTHESIS

A combination of proximal and distal realignment procedures of the patella will reduce pain and increase function in adult patients with HDP.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twelve patients with 13 symptomatic cases of HDP of the knee underwent surgical treatment that included lateral release, medial retinaculum advancement, and the anteromedial tibial tubercle transfer procedure. The average period between dislocation and surgery was 10.8 years. One patient had an additional procedure, an open-wedge varus corrective osteotomy of the distal femur, because of a 20 degrees valgus deformity of the knee. The patellofemoral morphology study included routine and Merchant views of the knee and a computed tomography scan at full extension and at 30 degrees flexion of the knee, before the operation and at follow-up. Any associated intra-articular pathologic findings during the surgical procedure were addressed. Patellofemoral function was evaluated with the Kujala functional score before surgery and at the time of the final follow-up.

RESULTS

Chondromalacia of the patella over the medial facet and central ridge was grade III in 8 knees and grade IV in 5 knees. Corresponding chondral erosion of the lateral femoral condyle was noted in every knee. All patients were followed for an average period of 67.3 months (range, 25-103 months). The average preoperative Kujala functional score was 43.9 and the average postoperative score was 88.9 (P< .05). Radiographically, there was a statistically significant improvement in the congruence angle from 62.1 degrees +/- 15.0 degrees preoperatively to -2.7 degrees +/- 9.8 degrees postoperatively (P< .01) and in the lateral patellofemoral angle from -40.2 degrees +/- 9.3 degrees preoperatively to 1.4 degrees +/- 7.0 degrees postoperatively (P< .01). No patient has reported an episode of patellar dislocation after the surgical procedures.

CONCLUSION

Combined proximal and distal realignments of the patella effectively treat HDP in adults with associated high-grade patellofemoral chondromalacia.

Patellofemoral contact pressures and lateral patellar translation after medial patellofemoral ligament reconstruction

BACKGROUND

Overtensioning of medial patellofemoral ligament reconstructions may lead to adverse surgical outcomes.

HYPOTHESIS

Increasing tension on a medial patellofemoral ligament graft will increase patellofemoral contact forces and decrease lateral patellar translation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Patellofemoral contact pressures were measured in 8 fresh-frozen cadaveric knees before and after transection of the medial patellofemoral ligament and after a standardized reconstruction surgery. Contact pressures were measured at 3 knee angles (30 degrees , 60 degrees , and 90 degrees ) and under 3 levels of tension applied to the graft (2, 10, and 40 N). For each condition, patellar translation was measured at 30 degrees of knee flexion as a 22-N lateral force was applied.

RESULTS

Graft tension of 2 N restored normal translation, but 10 N and 40 N significantly restricted motion (5.2 mm and 1.9 mm, respectively). Compared with the intact knee, medial patellofemoral contact pressures significantly increased (P < .05) when 40 N of tension was applied to the reconstruction. Medial contact pressures were restored to normal with 2 N of graft tension. Lateral patellar translation was significantly greater (P < .05) after the medial patellofemoral ligament was cut (16.3 mm) compared with intact (7.7 mm).

CONCLUSION

Low (2-N) tension applied to a medial patellofemoral ligament reconstruction stabilized the patella and did not increase medial patellofemoral contact pressures. Higher loads (10 N and 40 N) progressively restricted lateral patellar translation and inappropriately redistributed patellofemoral contact pressures.

CLINICAL RELEVANCE

Overtensioning can be avoided by applying low loads to medial patellofemoral ligament reconstructions, which reestablished normal translation and patellofemoral contact pressures.

MPFL Reconstruction

The medial patellofemoral ligament has been recognized as the most important medial structure preventing lateral dislocation or subluxation of the patella. Numerous surgical techniques have been described to reconstruct this important structure in patients with patellofemoral instability. This paper reviews the relevant anatomy and biomechanics, published reconstruction options, and describes the surgical technique used at our institution using semitendinosus autograft to reconstruct the medial patellofemoral ligament.

Current Concepts on Anatomy and Biomechanics of Patellar Stability

This review describes anatomic features of the patellofemoral joint that relate to the stability and function of the joint. The role of the geometry of the articular surfaces, particularly the trochlear groove, it's depth and orientation, are described. The stabilizing actions of the medial and lateral retinaculae, that tether the patella from either side to guide it into the trochlear groove in the early phase of knee flexion, are related to the specific structures, the medial patellofemoral ligament, and the fibers originating from the ilio-tibial tract laterally. The quadriceps muscles have different orientations, and converge onto the patella not only from either side but also from posteriorly, thus pulling the patella onto the anterior aspect of the trochlea. Finally, these local factors are discussed in relation to overall limb alignment, which leads to the mechanical logic of more extensive surgical procedures such as femoral rotational osteotomy or tibial tuberosity medialization.

Radiographic landmarks for femoral tunnel placement in medial patellofemoral ligament reconstruction

BACKGROUND

Reconstruction of the medial patellofemoral ligament has recently become popular for restoring patellofemoral stability. Femoral insertion site anatomy of the medial patellofemoral ligament has been described. This anatomical insertion has been inferred to be the isometric point in medial patellofemoral ligament reconstruction, but data about radiographic landmarks for a postoperative or intraoperative control are missing.

PURPOSE

To determine the radiographic landmarks for control of postoperative and intraoperative femoral medial patellofemoral ligament insertion.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Eight fresh-frozen human knees were dissected, and the medial patellofemoral ligament was exposed. After identification of the femoral medial patellofemoral ligament insertion site, the insertion center was marked with a lead ball of 2-mm diameter. Straight lateral radiographs were taken, and posterior-anterior as well as proximal-distal position were evaluated.

RESULTS

Six of 8 insertion points were anterior to a line representing an extension of the posterior cortex, 1 point was touching this line, and 1 point was posterior to it. All points were situated distal to the posterior origin of the medial femoral condyle and proximal to the most posterior point of the Blumensaat line.

CONCLUSION

A reproducible anatomical and radiographic point, 1 mm anterior to the posterior cortex extension line, 2.5 mm distal to the posterior origin of the medial femoral condyle, and proximal to the level of the posterior point of the Blumensaat line on a lateral radiograph with both posterior condyles projected in the same plane, shows the mean femoral medial patellofemoral ligament center.

CLINICAL RELEVANCE

This radiographic point may be useful both intraoperatively and postoperatively.

In vitro measurement of patellar kinematics following reconstruction of the medial patellofemoral ligament

This study compares the effects of two different techniques of medial patellofemoral ligament (MPFL) reconstruction, and proximal soft tissue realignment on patellar stabilization against lateral dislocation. Eight human cadaver knee specimens with no radiological pathomorpholgy on a straight lateral view, contributing to patellofemoral instability, were mounted in a kinematic knee simulator and isokinetic extension was simulated. Patellar kinematics were measured with an ultrasound positioning system (zebris) while a 100 N laterally directed force was applied to the patella. The kinematics were compared with intact knee conditions under MPFL deficient conditions, as well as following dynamic reconstruction of the MPFL using a distal transfer of the semitendinosus tendon, following static reconstruction by a semitendinosus autograft, and following proximal soft tissue realignment of the patella (Insall procedure). Dynamic reconstruction of the MPFL resulted in no significant alteration (P = 0.16) of patellar kinematics. Static reconstruction of the MPFL significantly medialized (P < 0.01) the patellar movement without, but restored intact knee kinematics under the laterally directed force. In contrast, following proximal soft tissue realignment, the patellar movement was constantly medialized and internally tilted (P = 0.04). Dynamic and static reconstruction of the MPFL create sufficient stabilization of the patella. Following proximal soft tissue realignment, the patellar position was over-medialized relative to intact knee conditions, which could lead to an overuse of the medial retropatellar cartilage.

Dynamic measurement of patellofemoral contact pressure following reconstruction of the medial patellofemoral ligament: an in vitro study

BACKGROUND

Surgical reconstruction of the medial patellofemoral ligament used to stabilize the patella against lateral dislocation may concomitantly produce alteration of the patellofemoral contact pressure distribution. Two different tendon transfer techniques of reconstructing the medial patellofemoral ligament, one dynamic and one static, as well as a proximal soft tissue realignment of the patella were investigated.

METHODS

Eight human knee specimens were mounted in a kinematic knee simulator and isokinetic extension motion was simulated. Patellofemoral pressure was measured using a pressure sensitive film while a 100 N laterally directed dislocation load was applied to the patella. The specimens were evaluated in a physiologic state, as well as after dynamic reconstruction of the medial patellofemoral ligament using a distal transfer of the semitendinosus tendon, following static reconstruction using a semitendinosus autograft, and following proximal soft tissue realignment of the patella.

FINDINGS

Following both reconstruction techniques of the medial patellofemoral ligament patellofemoral contact pressure was not significantly (P=0.49) altered. In contrast, after proximal realignment a trend (P=0.07) towards higher contact pressure near knee extension was observed. In the absence of a lateral dislocation load dynamic and static reconstruction resulted in a medialization (P=0.04) of the center of pressure, whereas under the application of a 100 N dislocation load the center of pressure showed no significant alteration. Following proximal realignment the center of pressure was significantly medialized without (P<0.01) and with a dislocation load (P=0.01) throughout the entire range of knee motion.

INTERPRETATION

Static and dynamic ligament reconstruction of the medial patellofemoral ligament did not alter patellofemoral pressure. Proximal realignment, on the other hand, resulted in a constant medialization of the patellofemoral pressure. The data suggest that the reconstruction techniques would be associated with a low risk of causing premature cartilage degeneration due to excessive patellofemoral contact pressure, whereas proximal realignment could cause medial overload of the patellofemoral joint.

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.

Medial patellofemoral ligament reconstruction: a novel technique using the patellar ligament

In patients with chronic patellofemoral instability, more than 2 episodes of dislocation, and an anterior tuberosity trochlear groove of less than 20 mm as measured on computed tomography or nuclear magnetic resonance imaging, we have developed a technique for medial patellofemoral ligament reconstruction that uses a medial strip of the patellar ligament (PL). The incision started proximally at the level of the superior margin of the patella, centrally between the patellar medial margin and the medial epicondyle. A descending incision was then made, directed toward the superomedial margin of the tibial tubercle. We performed a plane-by-plane dissection up to the peritenon of the PL. With an osteotome, we could remove a 2-cm bone fragment concerning the medial third of the distal insertion of the PL or keep the distal end free. Using a No. 11 scalpel blade, we carefully detached the PL from the patella up to the transition between the proximal third and medial third of the patella. We placed the stitches between the periosteum and the ligament using FiberWire absorbable threads (Arthrex, Naples, FL) to safely rotate the graft. After that, we dissected the medial capsule and approached the femoral medial epicondyle. Then we placed a Krackow suture in the free tendon end using absorbable threads or anchored the threads into 2 holes that were previously drilled, and we secured the end with an absorbable interference screw or anchors. The fixation should be performed with the knee at 15 degrees to 30 degrees of flexion. Then we sutured the distal edge of the vastus medialis muscle to the graft, which bestows a dynamic component upon the reconstruction, and we immobilized the knee with a removable brace.

Technical errors during medial patellofemoral ligament reconstruction could overload medial patellofemoral cartilage: a computational analysis

BACKGROUND

The influence of reconstruction of the medial patellofemoral ligament on the patellofemoral force and pressure distributions has not yet been investigated.

HYPOTHESIS

Technical errors can cause tension to develop within a reconstructed medial patellofemoral ligament, which will adversely alter the normal patellofemoral force distribution by increasing the load applied to the medial cartilage.

STUDY DESIGN

Controlled laboratory study.

METHODS

Four computational knee models were used to simulate knee function from 30 degrees to 90 degrees of flexion with (1) an intact medial patellofemoral ligament, (2) an anatomically correct reconstruction using a double hamstring tendon autograft, (3) a 5-mm proximally malpositioned femoral attachment site, (4) a graft that is 3 mm shorter than the intact medial patellofemoral ligament, and (5) combined proximal malpositioning and a short graft.

RESULTS

The results were similar for the intact and anatomically reconstructed medial patellofemoral ligament. Proximal malpositioning of the femoral attachment and using a short graft increased the graft tension during flexion, which decreased the lateral force and the lateral tilt moment acting on the patella. When a short graft was combined with proximal malpositioning, the compressive force applied to the medial cartilage at least doubled at low flexion angles, which increased the peak medial pressure by more than 50% at low flexion angles.

CONCLUSION

When the medial patellofemoral ligament is reconstructed, small errors in graft length and position can dramatically increase the force and pressure applied to medial patellofemoral cartilage.

CLINICAL RELEVANCE

Overloading the medial cartilage after medial patellofemoral ligament reconstruction could lead to degradation, pain, and arthrosis.

Reconstruction of the medial patellofemoral ligament with autologous quadriceps tendon

In knees with insufficient or previously disrupted medial retinacular and patellofemoral ligaments caused by subluxation or dislocation, anatomic reconstruction of the medial patellofemoral ligament may be performed. This procedure involves harvesting of an 8 x 70-mm medial quadriceps tendon graft, which leaves the quadriceps tendon retinacular attachment intact and avoids patellar and femoral drill holes. This graft is passed beneath the retinaculum adjacent to the femoral epicondyle and is sutured to the medial intermuscular septum-a procedure that reproduces the medial patellofemoral ligament and is supported by imbrication of the remaining medial retinaculum. The tension of the graft and of the medial retinaculum is set at closure with the knee in 30 degrees to 45 degrees of flexion; this allows the patella to be moved a distance equal to 25% of its width. Avoidance of drill holes allows the procedure to be used regardless of skeletal maturity and reduces fracture complications, inadequate graft placement, and failure of fixation. Postoperative rehabilitation includes immediate knee motion from 0 degrees to 90 degrees and partial weight bearing.

Medial patellofemoral ligament reconstruction in patients with lateral patellar instability and trochlear dysplasia

BACKGROUND

Reconstruction of the medial patellofemoral ligament has been proven to restore stability in patients with lateral patellar instability. No study to date has examined the results in a patient population with the predisposing factor of femoral trochlear dysplasia.

HYPOTHESIS

Reconstruction of the medial patellofemoral ligament restores stability and provides pain relief in patients who have lateral patellar instability in association with trochlear dysplasia.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Thirty-four patients with chronic patellar instability and trochlear dysplasia were treated with medial patellofemoral ligament reconstruction using an adductor tendon autograft, bone-quadriceps tendon autograft, or bone-patellar tendon allograft. All patients were evaluated preoperatively and postoperatively with Kujala, Lysholm, and Tegner scores at a minimum of 24 months.

RESULTS

Thirty-four patients were followed for a mean of 66.5 months (range, 24-130 months) after surgery. Kujala scores improved from 53.3 to 90.7, Lysholm scores improved from 52.4 to 92.1, and Tegner activity scores improved from 3.1 to 5.1. All improvements were highly statistically significant (P < .001). No statistical difference was found between the postoperative Lysholm, Kujala, and Tegner scores and the degree of dysplasia, graft type, or degree of symptoms. There were 85.3% and 91.1% good and excellent results based on Kujala and Lysholm scores, respectively. No recurrent dislocations have occurred.

CONCLUSION

Medial patellofemoral ligament reconstruction provides excellent long-term pain relief and functional return in patients with patellar instability and femoral trochlear dysplasia. In addition, reconstruction prevents recurrent dislocation, despite the diminished bony constraint of a dysplastic trochlea.

Hybrid medial patellofemoral ligament reconstruction using the semitendinous tendon for recurrent patellar dislocation: minimum 3 years' follow-up

PURPOSE

The purpose of this study was to evaluate the results of a new hybrid medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar dislocation.

METHODS

Hybrid MPFL reconstruction by use of the semitendinous tendon was performed in 12 knees with recurrent patellar dislocation. The results were evaluated at a minimum follow-up of 3 years (mean, 4.2 years).

RESULTS

According to the grading system of Insall et al., the results were classified as excellent in 8 knees (66%), good in 2 (17%), and fair in 2 (17%), with none being classified as poor. The mean Kujala score was 56.3 points (range, 29 to 82) preoperatively and 96.0 points (range, 84 to 100) at follow-up. There were no patients with recurrent dislocation and subluxation. No knees had a positive apprehension sign, and there were no postoperative complications.

CONCLUSIONS

At a midterm follow-up, hybrid MPFL reconstruction by use of the semitendinous tendon for recurrent patellar dislocation should be considered as an effective operation for cases without severe predisposing factors.

LEVEL OF EVIDENCE

Level IV, therapeutic case series, no or historical control group.

Arthroscopic release of the vastus lateralis tendon for recurrent patellar dislocation

BACKGROUND

Arthroscopic release of the vastus lateralis tendon for treatment of recurrent patellar dislocation has been criticized on the grounds that it may weaken the quadriceps.

HYPOTHESIS

Quadriceps strength and outcome measures improve after arthroscopic release of the vastus lateralis tendon in patients with documented patellar dislocation.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty patients who had recurrent patellar dislocation underwent arthroscopic lateral retinacular release that included a complete release of the vastus lateralis tendon from the superior pole of the patella and were observed prospectively. Bilateral quadriceps strength was tested preoperatively and at follow-up with an isokinetic dynamometer. Patients also completed the International Knee Documentation Committee Subjective Knee Form and the Short Form-36 preoperatively and postoperatively.

RESULTS

Follow-up averaged 27 months (range, 24-43 months). There were no redislocations. Mean quadriceps strength improved by a mean of 28% (from 32.3 to 41.4 N x m). The mean quadriceps torque ratio (involved/uninvolved) improved significantly from a preoperative value of 63% (31/51 N x m) to 80% (42/52 N x m) at follow-up (P = .017). Fourteen patients (70%) increased quadriceps torque, and 6 patients (30%) decreased quadriceps torque. Only 1 patient failed to improve on International Knee Documentation Committee and Short Form-36 scores. The International Knee Documentation Committee scores improved from 45 points preoperatively to 76 points at follow-up (P = .001). The Short Form-36 physical component summary scores improved from 38 points preoperatively to 50 points at follow-up (P = .007), and the Short Form-36 physical functioning subscale scores improved from 53 points to 86 points (P = .015).

CONCLUSION

Arthroscopic release of the vastus lateralis tendon and lateral patellar retinaculum in patients with recurrent patellar dislocation can improve quadriceps strength and knee function.

In vitro investigation of the effect of medial patellofemoral ligament reconstruction and medial tibial tuberosity transfer on lateral patellar stability

PURPOSE

Two different operative techniques for stabilizing the patella against lateral displacement movement were investigated.

TYPE OF STUDY

In vitro experimental study.

METHODS

Five human cadaver knee specimens with a normal Q-angle were mounted in a kinematic knee simulator and investigated under simulated isokinetic extension motions. Patellar movement was measured while a 100-N laterally directed subluxation load was applied to the patella. Ligament loading of the medial patellofemoral ligament was measured using a strain gauge based buckle transducer inserted in the fibers of the ligament. The knee was evaluated in an intact physiologic state, as well as after medial transfer of the tibial tuberosity, and after the medial patellofemoral ligament was transected and reconstructed using a hamstring autograft.

RESULTS

A significant reduction in lateral displacement and ligament load was observed with the use of the hamstring autograft reconstruction compared with the medial transfer of the tibial tuberosity.

CONCLUSIONS

Medial transfer of the tibial tuberosity showed no significant relief of ligament loading and stabilizing effect on patellar movement, whereas reconstruction of the medial patellofemoral ligament showed a significant stabilizing effect on patellar movement.

CLINICAL RELEVANCE

In cadaver specimens, we evaluated the effect of tibial tubercle transfer and the patellofemoral ligament and found that reconstruction of the patellofemoral ligament alone was sufficient to restore stability in a cadaveric model. Additionally, we found that the flexion angle had little effect on the loading of the medial patellofemoral ligament autograft, which would support early mobilization of patients after surgery. We found that the graft was not unduly loaded.

Anatomical analysis of the medial patellofemoral ligament of the knee, especially the femoral attachment

The purpose of this study was to investigate the anatomical morphology and measurement of the medial patellofemoral ligament (MPFL), especially the femoral attachment. A total of 20 knee specimens were dissected and the total length, width, thickness, inclination, as well as the attachment points of the MPFL were measured. The MPFL was well-developed in seven knees, moderate in ten knees and wispy in three knees. Total length of the MPFL was 58.8 +/- 4.7 mm. The width and thickness was 12.0 +/- 3.1 mm and 0.44 +/- 0.19 mm at the middle point. The long axis of the MPFL inclined at 15.9 +/- 5.6 degrees proximally. The center of the patellar attachment was located at 27 +/- 10% from the upper end of the patella in the longitudinal patellar height. The femoral attachment was superoposterior to the medial femoral epicondyle and just distal to the adductor tubercle. The center of the anterior edge of the femoral attachment was 9.5 +/- 1.8 mm proximally and 5.0 +/- 1.7 mm posteriorly from the center of the medial femoral epicondyle. The femoral attachment was located at 61 +/- 4% of anteroposterior length of the medial femoral condyle from the anterior edge.

Clinical and radiological outcome of medial patellofemoral ligament reconstruction with a semitendinosus autograft for patella instability

BACKGROUND

Recurrent patellar instability is a common problem after dislocation. The medial patellofemoral ligament (MPFL) contributes 40-80% of the total medial restraining forces. This study assessed the clinical and radiological outcome after a follow-up of 4 years after linear MPFL reconstruction using an ipsilateral Semitendinosus tendon autograft.

STUDY DESIGN AND METHODS

15 knees in 12 patients were examined with a mean of 47 months after linear reconstruction of the MPFL at a mean age of 30 years. 3 knees underwent previous surgery. 3 patients had mild trochlear dysplasia grade I or II, according to the classification of Dejour. If preoperative tibial tuberosity-trochlear groove distance (TTTG) was more than 15 mm, patients underwent additional medialisation of the tibial tuberosity (n=8) creating a similar postoperative situation for all patients. All patients were available for a postoperative evaluation, which consisted of a subjective questionnaire, the Kujala score, and the recording of potential patellar redislocation and apprehension. Patellar height and tilt was measured on plain radiographs. Postoperative CT scans were performed in patients with an additional tibial tuberosity-transfer.

RESULTS

Postoperatively, one patient reported on recurrent bilateral redislocation. Physical examination however revealed no findings. Three knees presented with persistent patellar apprehension. Thirteen knees had improved subjectively after surgery. The mean Kujala score improved significantly from 55.0 to 85.7 points. The patellar tilt decreased significantly from 11.3 degrees to 9.2 degrees. Four knees had patella alta preoperatively, but only two at the latest follow-up visit. Previous surgery or additional trochlear dysplasia had no influence on the clinical outcome.

CONCLUSION

MPFL reconstruction improves clinical symptoms, reduces the patellar tilt substantially, and may correct patella alta. Additional mild trochlear dysplasia did not compromise the outcome; however, this fact needs further attention in a larger study group.

Plastie du ligament fémoro-patellaire médial avec le tendon du gracile pour stabilisation de la patella

We describe a technique for patellar stabilization by reconstruction of the medial patellofemoral ligament with the gracilis tendon. The tendon is anchored posteriorly on the soft tissue of the medial femoral epicondyle and anteriorly on the medial border of the patella. The plasty is completed by suture of the medial patellar wing. Inferior or medial transposition of the tibial tubercle may be associated. We have used this technique since 1995 for 145 knees with patellar instability. The small incisions have the advantages of minimally invasive surgery, particularly for the postoperative period and the cosmetic effect.

Mini-open medial reefing and arthroscopic lateral release for the treatment of recurrent patellar dislocation: a medium-term follow-up

BACKGROUND

Although recurrent patellar dislocations are not uncommon, their pathophysiology and treatment are controversial.

HYPOTHESIS

Stabilization of recurrent patellar dislocations can be successfully managed with a mini-open approach.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-two patients (23 knees) underwent a mini-open medial reefing and arthroscopic lateral release for the treatment of recurrent patellar dislocations with an average follow-up of 4.4 years (range, 1.4-14 years). The average age at the first dislocation was 15 years (range, 5-26 years), and the average age at surgery was 23 years (range, 12-65 years).

RESULTS

There was 1 postoperative dislocation (4%) and 1 recurrent subluxation (4%). The average Kujala knee score was 88.2 +/- 13.5, with overall good scores in each category. The lowest scores involved squatting (5.7), abnormal painful kneecap movements (subluxations) (7.1), and jumping (7.9). Overall, there was a statistically significant improvement in the Tegner score from 3.7 +/- 1.8 before surgery to 6.9 +/- 2.0 after surgery (P < .001). Six knees (26%) were rated subjectively as excellent, 15 (65%) as good, 2 (9%) as fair, and 0 (0%) as poor. All 22 patients (100%) stated that the procedure was worthwhile. Radiographically, there was a statistically significant improvement in the congruence angle (normal, -8.0 degrees +/- 6.0 degrees) from 15.7 degrees +/- 12.6 degrees (range, 0.0 degrees to +44.0 degrees) before surgery to -11.5 degrees +/- 8.7 degrees (range, -20.0 degrees to +10.0 degrees) after surgery (P < .001) and in the lateral patellofemoral angle (normal, >0 degrees) from -0.2 degrees +/- 6.4 degrees (range, -10 degrees to +8 degrees) before surgery to 7.9 degrees +/- 2.6 degrees (range, 0.0 degrees to +11.0 degrees) after surgery (P < .001).

CONCLUSION

Our mini-open technique provides anatomical restoration with limited morbidity and cosmetically appealing results. Furthermore, our redislocation rates compare favorably with traditional, more extensile open approaches.

Acute and recurrent patellar instability in the young athlete

Many reports of patellofemoral instability treatment suffer the same flaws of inappropriate patient selection, poor injury definition, insufficient activity assessment, and, especially in skeletally immature patients, limited followup found in other orthopedic literature. A significant number of dogmatic statements concerning risk factors and treatment interventions continue to be recycled through the literature without adequate clinical or laboratory substantiation, even in the face of contradictory data. Traditionally, patellar instability has been treated with variable periods of immobilization, sporadic rehabilitation, and an expected full return to sports activity. The reality is that many young athletes have long-term retropatella pain and sport-limiting extensor mechanism impairment following patellar dislocations. Most athletes benefit from an initial nonoperative program that is aggressive, multidimensional, and responsive to early treatment outcomes. Concurrent osteochondral injuries are common and a major contributor to adverse outcomes. Diagnostically, MRI is improving in its ability to detail osteochondral injury and it plays an important role in determining the location and extent of MPFL injury. The primary stabilizing role of the MPFL in the normal knee and its injury as an essential lesion of patella instability has been appreciated only recently. There is growing interest in exchanging the myriad of nonanatomic extensor mechanism reconstructions for more anatomic procedures based on restitution of the MPFL.