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© 1997 The Journal of Bone and Joint Surgery, Inc. Open Lateral Retinacular Lengthening Compared with Arthroscopic Release. A Prospective, Randomized Outcome Study* , NASSAU BAY, TEXASInvestigation performed at St. John Sports Medicine Center, Nassau Bay
A prospective, randomized study was performed to compare the results of arthroscopic lateral retinacular release (Group I) with those of open lateral retinacular lengthening (Group II). The study included eighty-six patients (eighty-six knees) who had had pain in the anterior peripatellar aspect of the knee and lateral patellar tilting (rotational malalignment), as seen on Merchant tangential patellofemoral radiographs, that had not improved after participation in a structured rehabilitation program for the quadriceps and the hamstrings for a minimum of six months. The mean duration of follow-up after the operative procedures was forty-six months (range, two to six years). At the time of the latest follow-up evaluation, forty (93 per cent) of the forty-three patients in Group I and all forty-three (100 per cent) of the patients in Group II had resumed the level of athletic activity that they had engaged in before the onset of symptoms (p = 0.08, analysis of variance). With the numbers available for study, no significant difference could be detected between the groups with regard to deficits in the range of motion, atrophy (the circumference) of the thigh, operative or postoperative complications, or the need for subsequent operative procedures. Additionally, no significant difference could be detected between the groups with regard to the results of open or closed-chain testing with an isokinetic dynamometer. According to the knee-rating system of Lysholm and Gillquist as modified by Tegner and Lysholm, thirty-three knees (77 per cent) in Group I had a score of 80 points or more compared with thirty-eight knees (88 per cent) in Group II. Six knees (14 per cent) in Group I had a score of less than 70 points compared with no knees in Group II. The difference in the knee ratings between the two groups was significant (p = 0.028, analysis of variance). Although there seemed to be a definite trend toward improved function of the knee in association with a longer duration of follow-up, no significant association could be detected between the duration of follow-up and improvement in the outcome measures in either group.
Pain in the anterior peripatellar aspect of the knee is a frequent symptom in active adolescents and young adults2-6,8-13,16,21,23,25-28,33,37,40,44. It has been reported to affect as many as one in four individuals in the general population27,33. Trauma and anatomical malalignment are frequent causes of patellar pain2,3,5,6,8,12,24,28; however, in a distinct subset of patients, no predisposing anatomical or traumatic factor can be identified. Fulkerson et al. radiographically identified a population of patients who had lateral patellar tilting without subluxation and with chronic peripatellar pain8-11,13. Ficat and Hungerford used the term "excessive lateral pressure syndrome"5; Larson et al., "patellar compression syndrome"28; and others, "patellofemoral stress syndrome"27,40 to describe patellar symptoms that did not seem to be related to instability or malalignment. It has been shown that, when rehabilitation of the quadriceps and stretching of the hamstrings fail to relieve symptoms, as is the case in 15 to 20 per cent of patients (in studies ranging from as few as thirty to as many as 700 patients), operative treatment can be successful4-6,9-11,13,16,18,19,21,26,27,30,33,37,40,43. Ceder and Larson3 as well as Larson et al.28 reported rates of success of 81 per cent (fifty-two of sixty-four patients) and 82 per cent (forty-six of fifty-six patients) after a lateral retinacular z-lengthening procedure. McGinty and McCarthy reported a similar rate of success (82 per cent; thirty-two of thirty-nine patients) after arthroscopic lateral retinacular release34. Theoretically, the weakness caused by the complete division of the vastus lateralis obliquus and the egress of synovial fluid into the subcutaneous tissues can be avoided with use of open lateral retinacular lengthening, which also affords the surgeon an optimum field for hemostasis and the potential to avoid postoperative hemarthroses3,28. A long-term advantage was believed to be faster rehabilitation of the quadriceps secondary to an intact yet lengthened retinaculum. The advantages of arthroscopic release include less discomfort related to the incision and a better cosmetic result34; the disadvantages include a release that is too extensive and hemarthroses7,9,11,15,16,27,37. The purpose of the current prospective, randomized study was to determine the outcome of open lateral retinacular lengthening compared with that of arthroscopic lateral retinacular release in a subset of patients who had lateral patellar tilting (rotational malalignment as described by Fulkerson et al.13) without patellar subluxation or dislocation and who did not have resolution of the symptoms after a six-month rehabilitation program.
Five hundred and seventy-one patients who had pain in the anterior aspect of the knee that was believed to be secondary to lateral patellar tilting were entered into a rehabilitation protocol between July 1989 and January 1994. If physical examination revealed no associated abnormalities or internal derangements of the knee and if there was less lateral than medial patellofemoral cartilage space on the Merchant radiograph38, the patient was started on a home program of progressive strengthening of the quadriceps and adductor muscles and stretching of the hamstrings and the iliotibial band27,40. If there had been no improvement by six weeks, the limb was placed in a patellar stabilizing knee-sleeve and oral administration of anti-inflammatory agents was begun. If an additional six-week period of rest from the inciting activity and additional formal outpatient physical therapy, including patellar taping33, failed to relieve the symptoms, the patient became a candidate for operative treatment. Approximately one-third of the patients (thirty of ninety-one) who became candidates for operative intervention had had transient relief of the pain for two to three weeks after the patellar taping; the taping did not exacerbate the symptoms in any patient. Patients who had had no improvement after six months of non-operative treatment, did not have a work-related injury or pending litigation, had unilateral pain in the anterior aspect of the knee, and had not had a previous patellar realignment or retinacular procedure were entered into the study. Eligible patients were told that both procedures had been found to relieve symptoms effectively in four of five patients and that there were advantages and disadvantages to both. Specifically, open lateral retinacular lengthening has the disadvantage of a less cosmetically appealing incision. Although arthroscopic lateral retinacular release has very little cosmetic effect on the tissues of the knee, postoperative hematoma, infection, weakness of the muscles about the knee, and continued pain (perhaps even more than the patient had had preoperatively) have been reported5,7,9,11,15,37. Patients who were randomized to treatment with open lateral retinacular lengthening were told that reported complications3,28 have included deep venous thrombosis, stitch abscess, and even neuroma caused by the cutting of nerves in the tissues around the knee. They also were informed that if they did not choose to participate in the study, they would be followed for six months postoperatively at six-week intervals and then on an annual basis, at no cost to them, for the duration of the study or for a minimum of two years. The patient then chose whether or not to be included in the study. After approval from the institutional review board had been obtained, patients were randomized to treatment with arthroscopic lateral retinacular release (Group I) if they had been born in an even-numbered year or to treatment with open lateral retinacular lengthening (Group II) if they had been born in an odd-numbered year. One hundred and eight patients were eligible for the study, but seventeen refused to have the operation, leaving ninety-one patients (forty-four in Group I and forty-seven in Group II). One patient in each group was lost to follow-up, and three patients in Group II were later determined to have had previous lateral retinacular procedures and were excluded from this prospective analysis. Thus, the final study group consisted of eighty-six patients (eighty-six knees), with forty-three patients in each group. No comparison was made between these patients and the seventeen patients who had refused operative management. Group I consisted of seventeen male patients (mean age, eighteen years; range, thirteen to fifty-six years) and twenty-six female patients (mean age, thirty-three years; range, fifteen to forty-seven years). Group II consisted of eighteen male patients (mean age, twenty-two years; range, thirteen to thirty-three years) and twenty-five female patients (mean age, thirty-four years; range, fourteen to fifty-nine years). Group I comprised sixteen left knees and twenty-seven right knees, and Group II comprised twenty-three left knees and twenty right knees. The patients in Group I had had the symptoms for a mean of 29.8 months (range, six to 220 months), and the patients in Group II had had the symptoms for a mean of 26.4 months (range, six to ninety-six months). All of the patients were followed for two to six years. The mean duration of follow-up was 46.6 months (range, twenty-four to seventy-three months) for Group I and 43.1 months (range, twenty-four to seventy-two months) for Group II. With use of analysis of variance, no significant difference was found between the groups in terms of age (p = 0.57), gender (p = 0.83), or the preoperative duration of symptoms (p = 0.62).
Operative Technique
Arthroscopic Lateral Retinacular Release
Open Lateral Retinacular Lengthening The dissection is then carried out laterally for two centimeters. A flap of lateral retinaculum superficial to the lateral aspect of the knee capsule and the deep retinaculum is raised from the fibers of the vastus lateralis superiorly to just beyond the tibial joint line. The deep fibers of the retinaculum and the superficial capsule then are incised two centimeters lateral to, and along the length of, the overlying retinacular incision (Fig. 2-A). This dissection can be difficult; any areas of penetration of the capsule or the synovial tissue are sutured with 2-0 absorbable sutures. The medial free edge of the capsule and the deep retinacular fibers then are sutured to the lateral free edge of the superficial lateral retinaculum with 2-0 absorbable sutures, thus effecting the lateral retinacular lengthening (Fig. 2-B).
Previous Operations Five patients (three male and two female) in Group II had had a total of six previous operations. The three male patients and one of the female patients had had one operation, and the other female patient had had two operations. The operations included two partial medial meniscectomies, two excisions of a medial synovial plica, one diagnostic arthroscopy, and one repair of the medial collateral ligament.
Concomitant Procedures Twenty-one patients (49 per cent) in Group II had a total of twenty-seven additional procedures concomitant with the open lateral retinacular lengthening. All but one of these procedures was done arthroscopically. The one open procedure was a reconstruction of the medial collateral ligament, performed with use of a semitendinosus autogenous graft for the treatment of symptomatic, chronic laxity of the medial collateral ligament after a previous repair of the ligament had failed. The twenty-six arthroscopic procedures included eight chondroplasties of the medial femoral condyle, seven excisions of a medial synovial plica, five procedures for the removal of a loose body, and six partial meniscectomies (three medial and three lateral). With use of analysis of variance, no significant difference could be detected between the groups with regard to the percentage of patients who had had a previous operative proceedure (p = 0.37) or a concomitant operative procedure (p = 0.83).
Postoperative Regimen The patients were seen in my office two weeks postoperatively. At that time, progressive-resistance quadriceps-strengthening exercises were reemphasized and a running-and-cycling exercise regimen was begun. The patients were allowed to return to competitive athletic activity after the sixth postoperative week. Orthopaedic evaluation was performed two, six, and twelve weeks postoperatively and annually thereafter. Merchant radiographs were made preoperatively and on an annual basis postoperatively. A frame was constructed so that the knee could be flexed reproducibly to 45 degrees and a tangential patellofemoral (Merchant) radiograph38 could be made 30 degrees distal to the horizontal plane. The congruence angle was measured on the Merchant radiograph. This angle is formed by the bisector of the femoral trochlear sulcus, which serves as the zero reference line, and the line between the most distal point of the femoral sulcus and the most distal point on the articular ridge of the patella. Values that are medial to a zero reference line are designated as negative and those that are lateral, as positive38. Function was evaluated at yearly intervals, according to the system of Lysholm and Gillquist32 as modified by Tegner and Lysholm45. I (the treating physician) was not involved in the most recent follow-up evaluation in order to avoid biasing the patient's interpretation of the result. It has been shown that there are discrepancies between patients' and physicians' evaluations of the outcomes of orthopaedic procedures31. This discrepancy can increase when the patient is not satisfied with the outcome. Open-chain testing of the extensors of the knee was performed with an isokinetic dynamometer (Lido, West Sacramento, California) at yearly intervals postoperatively. Peak torque and total work were measured in foot-pounds (one foot-pound equals 1.356 newton-meters). Concentric extension of the knee was tested between 90 and 0 degrees of flexion, at isokinetic velocities of 60, 180, and 240 degrees per second, with the patient seated and the waist and the distal aspect of the thigh strapped for stabilization. Deficits were recorded at all of the levels that were tested. Closed-chain testing of the extensors was performed with a closed-chain isokinetic dynamometer (Lido Linea, West Sacramento, California), also at yearly intervals. Peak torque and total work were measured in foot-pounds. Bilateral reciprocal concentric leg-press was tested between 90 and 0 degrees of flexion of the knee, at isokinetic velocities of ten, twenty, and thirty inches (25.4, 50.8, and 76.2 centimeters) per second, with the patient seated and the waist strapped for stabilization. Deficits were recorded at all of the levels that were tested. The range of motion of the knee and the circumference of the thigh were measured at annual intervals postoperatively, and these measurements were compared with those for the uninvolved limb. Any deficit in the range of motion compared with that on the contralateral side was recorded. The circumference was measured with a tape at the joint line and three and seven inches (7.6 and 17.8 centimeters) proximal to the joint line, and any deficit compared with the circumference on the contralateral side was recorded. The greatest recorded deficit was used for statistical analysis.
Statistical Analysis
Duration of Preoperative Symptoms No significant association could be detected between the duration of symptoms and any of the outcome measures for the patients in Group II.
Chondromalacia Patellae Thirty-five patients (81 per cent) in Group II had no arthroscopically evident chondromalacia patellae. Of the remaining eight patients (19 per cent), two (5 per cent)—both female patients who were thirty-six and forty-two years old—had grade-II chondromalacia of the lateral patellar facet; five (12 per cent)—female patients whose ages ranged from forty-six to fifty-nine years old—had grade-III chondromalacia of either the medial or the lateral facet or the midline raphe; and one (2 per cent)—a boy who was thirteen years old—had grade-IV chondromalacia of the medial facet. The rate of arthroscopically demonstrable chondromalacia patellae was significantly greater in Group I (p = 0.005, analysis of variance) (Table I).
Return to Pre-Injury Level of Activity All three patients who had given up athletic activity had done so because of pain in the anterior aspect of the knee. One of these patients, a thirty-year-old woman who had given up league softball, had had grade-III chondromalacia of the midline raphe at the time of the operation. Postoperatively, she had a score of 84 points on functional testing32,45 and a 0-degree congruence angle as seen on the Merchant radiograph. At the latest follow-up evaluation, sixty-two months postoperatively, she had a 30 per cent quadriceps deficit on isokinetic testing and an eighteen-millimeter decrease in the circumference of the thigh. The second patient was a thirty-three-year-old woman who had given up jogging. She had had no demonstrable chondromalacia at the time of the operation. Postoperatively, she had a score of 89 points on functional testing, a -10-degree congruence angle, and no deficits on isokinetic testing despite a ten-millimeter decrease in the circumference of the thigh. At the latest follow-up evaluation, forty-six months postoperatively, she had lost 10 degrees of terminal flexion. The third patient was a forty-one-year-old man who had given up jogging. He had had grade-II chondromalacia of the midline raphe at the time of the operation. Postoperatively, he had a score of only 48 points on functional testing, a -3-degree congruence angle, and a 16 per cent quadriceps deficit on isokinetic testing, with no atrophy or loss of range of motion. The seventeen-year-old girl in Group I who had had grade-IV chondromalacia resumed playing collegiate-level volleyball postoperatively, and the forty-seven-year-old woman who had had grade-IV chondromalacia, also in Group I, resumed jogging. The thirteen-year-old boy in Group II who had had grade-IV chondromalacia of the medial facet resumed playing junior-high-school basketball, but he was subsequently not selected for the high-school team.
Testing with the Dynamometer Sixteen patients (37 per cent) in Group I had a quadriceps deficit, ranging from 1 to 25 per cent, on closed-chain testing. These deficits reflect the greatest side-to-side differences in total work at ten, twenty, and thirty inches (25.4, 50.8, and 76.2 centimeters) per second. The deficit was 10 per cent or less in nine patients, 11 to 20 per cent in four, and 21 to 30 per cent in three. Thirteen patients (30 per cent) in Group II had a quadriceps deficit, ranging from 2 to 11 per cent, on closed-chain testing. Sixteen patients (37 per cent) in Group I and nine patients (21 per cent) in Group II had a quadriceps deficit on open-chain testing of peak torque. In Group I, the deficit was 10 per cent or less in nine patients, 11 to 20 per cent in three, and 21 to 30 per cent in four. Seven patients (16 per cent) in Group II had a deficit of 10 per cent or less on open-chain testing, and two (5 per cent) had a deficit of 15 per cent. There was a trend for the patients in Group II to perform better than those in Group I on open-chain testing at 60 and 180 degrees per second and on testing at peak torque (but not at the 95 per cent confidence level). At 60 degrees per second, the p value for the difference between the groups was 0.09, according to analysis of variance, and at 180 degrees per second, the p value was 0.10. The p value for the difference between the groups on testing of peak force was 0.10, according to analysis of variance (Table I). No significant differences could be detected on closed-chain testing at ten, twenty, or thirty inches (25.4, 50.8, or 76.2 centimeters) per second.
Range of Motion In Group II, five patients (12 per cent)—a fourteen-year-old boy and four female patients ranging in age from fourteen to forty-three years old—had a loss of flexion ranging from 2 to 23 degrees. No patient in Group II had a loss of extension. Only one patient in each group had a loss of more than 10 degrees of flexion. No significant difference could be detected between the two groups with regard to loss of motion (p = 0.75, analysis of variance) (Table I). The precision of the measurement was ±5 degrees.
Circumference of the Thigh In Group II, seven patients (four male and three female; 16 per cent) had a decrease in the circumference ranging from five to eighteen millimeters. No significant difference could be detected, with regard to the change in circumference, between the two groups (p = 0.31, analysis of variance) (Table I). The precision of the measurement was ±5 millimeters.
Complications and Subsequent Operative Procedures Three patients (7 per cent) in Group II had postoperative complications, including a stitch abscess in a sixteen-year-old girl, a keloid of the skin incision in a fourteen-year-old girl, and an inability to flex the knee more than 90 degrees four weeks postoperatively in a twenty-three-year-old man. Two patients (5 per cent) in Group I had an additional operation. The patient who had the contracture of the iliotibial band had a release of the band thirty-two months postoperatively, and the patient who had the joint infection had arthroscopic irrigation and débridement three weeks postoperatively. Both of these patients were able to return to their previous level of activity after the additional procedure. In Group II, only one patient (2 per cent), the man who had early loss of flexion, had an additional procedure. The knee was manipulated to full flexion with the patient under anesthesia, and the limb was placed in a splint with the knee in 125 degrees of flexion. The patient subsequently returned to his previous level of activity. The difference in the numbers of patients in each group who had complications (p = 0.70) and additional procedures (p = 0.31) could not be shown to be significant with analysis of variance (Table I).
Findings on Merchant Radiographs
The patients in Group II had a mean congruence angle of -2 degrees (range, +30 to -40 degrees) preoperatively compared with -7 degrees (range, +25 to -32 degrees) postoperatively (Figs. 4-A, 4-B, 5-A and 5-B). The average correction was 3.6 degrees (mean, 1 degree; range, 23 degrees of lateralization to 56 degrees of medialization).
There was a significant difference in the preoperative and postoperative congruence angles between the groups. The patients in Group I had less medialization (p = 0.02, analysis of variance) than did those in Group II; however, no significant difference could be detected with regard to the amount of correction (medialization) achieved with either procedure. No significant association could be detected between the amount of correction and the functional outcome (p = 0.1, Wilcoxon rank-sum test).
Functional Testing The mean knee score in Group I was 89 points (average, 85 points; range, 40 to 100 points), and the mean score in Group II was 91 points (average, 91 points; range, 70 to 100 points). Thirty-three patients (77 per cent) in Group I had a good or excellent result (a score of 80 points or more) compared with thirty-eight patients (88 per cent) in Group II. The results for the knee scores are inconclusive. According to analysis of variance, this self-reported score was significantly different between the two groups at the 97 per cent confidence level (p = 0.028) (Table I).
Duration of Follow-up
The results of arthroscopic lateral retinacular release (Group I) and open lateral retinacular lengthening (Group II) in this prospective, randomized series of patients are consistent with those that have been reported previously3-5,7,9-11,16,18,26,28,34. However, in the current study, the open lateral retinacular lengthening procedure was associated with significantly better knee scores32,45 at the 95 per cent confidence level (p = 0.028, analysis of variance). Although the ability to return to the previous level of athletic activity, the results of isokinetic testing with a dynamometer at 60 and 180 degrees per second, and the isokinetic peak-force measurements appeared to be better after open lateral retinacular lengthening, these values were not found to be significant at the 95 per cent confidence level. The treatment of patellofemoral pain is controversial. Most patients have relief after non-operative management3-12,14,16-19,21-23,25-28,33,35-37,39-42,44,47. However, Fulkerson et al. reported that patients with lateral patellar tilt (rotational malalignment) who had pain in the anterior aspect of the knee that did not respond to an exercise regimen had relief after a lateral retinacular procedure9,11,13. Good results have been reported after both arthroscopic and open lateral retinacular procedures3-5,10,16,18,21,23,28,37,44, but I know of no previous attempt to randomize similar patients prospectively to the different operative groups. In particular, I am aware of no study in which objective muscle-testing was performed and the range of motion, circumference of the thigh, radiographic patellofemoral congruence, and functional status were measured in prospectively randomized operative subgroups. Tangential radiographic patellofemoral evaluation was an important objective measurement in this study. Merchant radiographs were made for all patients preoperatively and at the latest follow-up evaluation. Many objective radiographic methods and tools are available for evaluation of the patellofemoral articulation1,2,13,20,29,38,44,46, but the Merchant radiograph is popular worldwide because of its reproducibility and cost-effectiveness. However, the Merchant radiograph has drawbacks. One patient in the current series had improvement in the functional status as well as a decrease in lateral patellar rotation, but, with the decreased lateral patellar tilt, the congruence angle on the Merchant radiograph actually lateralized from +23 to +36 degrees (Figs. 3-A and 3-B). Additionally, all three patients in Group I who gave up athletic activity had medialization of the patella on the latest Merchant radiograph. Thus, the validity of the association between the findings on Merchant radiographs and the functional outcome was not borne out in this study. No attempt was made to associate the results with patellar configuration according to the classifications of Wiberg47 or Baumgartl1, as the clinical importance of patellar configuration remains in doubt9,10,17,21,26. While the current trend is to perform lateral retinacular procedures arthroscopically for the treatment of lateral patellar tilt, this practice should be considered critically. There was a significantly greater degree of chondromalacia41,42 in the patients in Group I (p = 0.005, analysis of variance); however, I am aware of no previous study documenting an association between the grade of chondromalacia and patellofemoral pain or the results of treatment5,6,9,10,21,26. The patients in Groups I and II were similar in all respects other than the grade of patellar chondromalacia. Of these similarly aged, athletic patients in whom pain in the anterior aspect of the knee had not resolved after six months of structured exercise, those who had had open lateral retinacular lengthening had significantly better knee scores over-all (p = 0.028, analysis of variance)32,45. In addition, although significance could not be detected at the 95 per cent confidence level, more patients who had had open lateral retinacular lengthening were able to return to their previous level of athletic activity and, on the average, these patients did better on open-chain testing of the knee extensor mechanism with the isokinetic dynamometer than did those who had had arthroscopic lateral retinacular release.
NOTE: The author thanks Peggy Scott, Sisters of Charity Hospitals, and Michael Woytik, Decision Supports Systems Research, for statistical analysis.
*Although the author has not received and will not receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article, benefits have been or will be received but are directed solely to a research fund, foundation, educational institution, or other non-profit organization with which the author is associated. Funds were received in total or partial support of the research or clinical study presented in this article. The funding source was Lido, West Sacramento, California.
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Abstract
Introduction
0.05. Analysis of variance and the Student t test assume that the measures are normally distributed; however, with small sample sizes, this assumption can be easily violated. The Wilcoxon rank-sum test is non-parametric, meaning that it makes no assumptions about the underlying distribution of the measures being tested. This test produces more conservative estimates of significance and therefore is relied on whenever there is a lack of agreement between its result and that obtained with analysis of variance. 
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