Surgical injury to the lateral aspect of the

Transcription

1 Surgical injury to the lateral aspect of the knee A comparison of transverse and vertical knee incisions* J. S. KEENE, M.D., J. N. AMALFITANO, M.D., W. G. CLANCY, JR., M.D., A. A. MCBEATH, M.D., AND R. G. NARECHANIA, M.S., Madison, Wisconsin From the Division of Orthopedic Surgery, Section of Sports Medicine, University of Wisconsin, Clinical Science Center, Madison, Wisconsin ABSTRACT We retrospectively evaluated postoperative straight lateral and anterolateral rotatory knee stability in patients having a lateral meniscectomy through vertical and horizontal capsular incisions. The knees of 20 patients with transverse (Bruser) and 20 patients with vertical (parapatellar) incisions were clinically and mechanically evaluated. Varus-vagus and anterior drawer measurements were obtained from our knee stress machine and clinical examinations. We found that (1) horizontal and vertical lateral capsular incisions do not produce straight lateral or anterolateral rotatory instability in patients with intact anterior cruciate ligaments, (2) a transverse lateral capsular incision may contribute to anterolateral rotatory instability, and (3) a vertical lateral capsular incision provides better visualization of the knee joint than a transverse incision. Lateral knee instability after athletic injury has been the subject of many recent reports. Some of these investigations focus on the importance of the lateral capsule to the structural integrity of the lateral aspect of the knee. On the basis of clinical and experimental observations, Johnsonl has concluded that the lateral capsular ligaments play a key role in anterolateral rotatory stability. Losse et a1.2 reported on 50 subjects operated on for anterolateral rotatory instability. They * Presented at the mtenm meetmg of the Amencan Orthopaedic Society for Sports Medicme, San Francisco, California, February 2 1 and 22, 1979 t Address correspondence to: J. S Keene, M.D., University of Wisconsm Hospitals, Clinical Science Center, Section of Sports Medicme, 600 Highland Avenue, Madison, Wisconsin concluded that the lateral capsule must be repaired to eliminate this lateral instability, and that reconstruction of the anterior cruciate, by itself, may not produce this result. In their extensive discussion of knee ligament instabilities, Hughston et al.3 emphasize that the middle third of the lateral capsule is not merely areolar tissue, but is a strong, major, static lateral knee support at 30 of flexion. However, there has been little discussion concerning straight lateral and anterolateral instability of the knee after lateral A number of incisions have been advocated for meniscectomy. lateral meniscectomy. Abbott, in his monograph on surgical approaches to the knee joint, discusses 15 different lateral incisions. Smillie,5 Pogrund,6 Aufranc,1 and Kaplan8 comment on the fact that the fat pad and the configuration of the lateral meniscus make exposure and resection more difficult than on the medial side of the knee. The majority of authors advocate a particular incision because it allows direct access to the lesion. The ideal incision allows optimal exposure and maintains maximal stability after surgery. Hughston et a1.3 reported one patient in which a transverse lateral meniscectomy incision was felt to have caused chronic anterolateral rotatory instability; therefore, they do not recommend the horizontal incision. In our study, knees of patients who had transverse (Bruser) capsular incisions were compared to those who had vertical (parapatellar) lateral capsular incisions. The lateral parapatellar approach requires vertical sectioning of the anterior third of the lateral capsule and the lateral patellar retinaculum. The Bruser approach requires an incision that parallels the fibers of the iliotibial band with the knee in acute flexion, but transversely cuts the anterior and middle thirds of the lateral capsule.9 This report documents the effect that the Bruser and the 93

2 lateral parapatellar incisions has on postoperative stability. MATERIALS AND METHODS lateral knee The knees of 40 patients with lateral incisions for lateral meniscectomies were retrospectively evaluated. There were 20 patients with transverse (Bruser) incisions and 20 patients with vertical (parapatellar) incisions. All of the patients were at least 1 year postoperation and were reported to have &dquo;normal stability&dquo; at the time of their memscectomy. None of the patients evaluated gave a history of subsequent injury to their operated knee. The average age for the Bruser patients was 43 years (range, 25 to 69 years). The average age for the parapatellar patients was 24 years (range, 17 to 43 years). Average follow-up time was 5 years, (range, 2 to 11 years) for patients with Bruser incisions and 1.5 years (range, 1 to 3 years) for patients with parapatellar incisions. Thirty-nine of the 40 patients evaluated were men. None of these patients had preoperative mechanical measurements. For each patient studied, a detailed history and physical examination, information from operative records, and values from testing on a knee-stress device were obtained and evaluated. The subjective and objective clinical data were recorded Fig. 1. Anterior drawer testing on the knee stress machine. Fig. 2. Valgus laxity being measured at 300 of flexion on the knee stress machine. Pelvic rotation is in the opposite direction of the applied force. on a standardized knee evaluation form. Clinical stability was graded 1 to 3+, based on millimeters of displacement. A grade of 1, 2, or 3+ corresponded to 5, 10, or 15 mm of joint displacement, respectively. The subjects had both knees mechanically tested on our knee stress machine. We (R. G. N., W. G. C., and G. C. R.) have described the design previously (in presentation, Annual Conference of Engineers in Medicine and Biology, Los Angeles, November 1977). R. G. N. documented that our knee stress machine eliminated potential measurement errors due to (1) femoral rotation in the frontal plane in varus-valgus testing, (2) forward femoral motion in the sagittal plane in anterior drawer testing, (3) constraint m the ligaments when the tibia moves on a transverse path, (4) nonalignment of the knee axis with the stress apparatus, and (5) unrecognized muscular activity during knee stress loading. Each subject s anterior drawer was measured in neutral, 15 of external and 30 of internal rotation as recommended by Slocum and Larson.1O The subject sat on the knee stress table with the leg under examination flexed at 90 The forward sagittal motion of the femur was prevented by placing a wooden beam directly in front of the patella. The subject s foot rested on an aluminum supporting plate that could be rotated from neutral to 15 external or 30 internal rotation. The foot support eliminated the problem of gravitational tension on the ligaments. A nylon nonextensible strap was placed around the was used proximal tibia. A Dacron rope attached to that strap to apply a force of 122 newtons. The tibial displacement was measured by strain gauges (Fig. 1). Each patient underwent varus-valgus testing at 0 and 30 of flexion. Femoral rotation was eliminated by rotation of the patient s pelvis and the upper body until the hip capsule was taut and the trochanter started to rotate. The pelvic rotation 94

3 was in the opposite direction of the applied force and was performed after the tibia and the knee were positioned in the measuring device. The distal end of the tibia was held by a clamp attached to two aluminum plates in which the upper one traveled in a sagittal direction while the lower plate traveled in a transverse direction. As a result, the tibia traveled a circular path when the weights were applied to this device. After the subject s pelvis was appropriately rotated, varus and valgus laxity were measured (Fig. 2). Each patient s uninjured, nonoperated, opposite knee was measured m a similar fashion. If the opposite knee was abnormal, average values obtained from a previously reported normal population served as the control. All varus-valgus and anterior drawer testing was done by a technician who had no knowledge of the results of each patient s clinical examination. Because we had patients with anterior cruciate ligament insufficiency, we could not evaluate postoperative stability solely on the basis of type of incision. Therefore, we assigned each patient, regardless of the type of incision, to one of two groups according to the condition of their anterior cruciate ligament. All patients with clinically intact anterior cruciate ligaments were put in Group 1. Group 1, thus included, 16 patients with Bruser incisions and 16 patients with lateral parapatellar incisions. The status of the anterior cruciate ligament was not documented in the operative note for eight patients with Bruser incisions. However, we found no significant difference on clmical or mechanical stress testing between the measurements of these eight patients with those that had cruciate ligaments documented to be intact. Therefore, all intact anterior patients with Bruser mcisions and clinically cruciate ligaments were put in Group 1. All patients with documented third-degree anterior cruciate insufficiency were put m Group 2. There were four patients with Bruser mcisions and four patients with lateral parapatellar incisions. RESULTS In Group 1 (anterior cruciate intact), there was less than 1- degree difference m the average varus or valgus measurements when normal and operated knees were compared. Average mechamcal values were slightly greater for the normal and operated knees in the patients with Bruser incisions. There was less than 1-mm difference in the anterior drawer measurement in Group 1 when normal and operated knees were compared. Average values for anterior drawer testing differed by less than 1 mm when the two incisions were compared. In Group I, none of the clinical estimates of varus-valgus, anterior, or anterolateral rotatory laxity were greater than 1+. Clinical estimation of knee laxity did correlate with the measured differences between knees m the same patient. Group 2 (anterior cruciate ligament deficient) also had less than 1-degree difference in varus or valgus measurements when the normal and operated knees were compared. However, the operated knee had greater than a 1-mm increase m the anterior drawer for both incisions. This abnormal anterior displacement was 50% greater in the patients with Bruser incisions as compared to the patients with parapatellar incisions. This greater mechanical laxity corresponded to increased clinical laxity in all of the patients in Group 2 with Bruser incisions, including the presence of a positive Lachman s and pivot patient with a vertical incision had a positive pivot The stress-testmg results for Groups in Tables 1 and 2. shift test. No shift test. 1 and 2 are summarized Group I TABLE 1 antenor cruciate mtact TABLE 2 Group 2 complete tear antenor cruciate ligament 95

4 DISCUSSION. Transverse and vertical lateral capsular knee incisions did not produce postsurgical varus or anterolateral rotatory instability in patients with intact anterior cruciate ligaments. At our institution, the transverse capsular incision was more often used in the earlier part of this decade. This explains the higher average age and longer length of follow-up time for the patients with Bruser incisions. The patients with Bruser incisions had slightly greater mechanical laxity in both their operated and unoperated knees. This difference may be explained by the higher average age of these patients, although we could not find a study that documents increased ligamentous laxity with age. There were eight patients with documented anterior cruciate insufficiency. Four of these persons had Bruser incisions and four had lateral parapatellar incisions. Varus laxity was minimally increased in both groups of patients. Hughston et a1.3 noted that significant anterolateral instability can be present without marked varus laxity. We (W. G. C. and R. G. N.) reported similar results. We mechanically measured patients with symptomatic anterolateral instability with documented Grade III anterior cruciate ligament injuries and found anterior instability markedly increased, but varus laxity only minimally increased in this group of patients. Mechanical stress-testing revealed abnormal anterior laxity in all eight patients with documented anterior cruciate ligament insufficiency. The patients with Bruser incisions had 50% greater anterior mechanical laxity in all positions than patients with parapatellar incisions. Only patients with Bruser incisions had clinical evidence (a positive pivot shift and jerk test) of anterolateral rotatory instability. Although the number of patients with Bruser incisions and absent anterior cruciate ligaments is small, our results suggest that a transverse lateral capsular incision may play a role in the development of the rotatory instability we observed. The results in anterior cruciate-deficient patients do not acquit the vertical capsular incision as a possible cause of anterolateral rotatory instability. Time may be the essential ingredient in the development of instability. The average follow-up time was only 1.5 years for the vertical incision patients as compared to 5 years for the patients with Bruser incisions. Eight of the 20 patients with Bruser incisions lacked operative documentation of the integrity of the anterior cruciate ligament. This may reflect the fact that a transverse (Bruser) incision permits only limited visualization of the knee joint. We prefer the lateral parapatellar mcision for lateral meniscectomy because it is easily extensible and offers better visualization of the (1) anterior cruciate ligament, (2) undersurface of the patella, and (3) anterior third of the medial meniscus. If one places the leg &dquo;tailor-fashion,&dquo; as described by Brown et al.&dquo; the intercondylar notch and posterior cruciate ligament can be inspected. This study suggests that (1) in patients with intact antenor cruciate ligaments, a transverse or vertical lateral capsular incision does not lead to measurable straight lateral or anterior lateral rotatory instability; (2) in patients with absent anterior cruciate ligaments, a lateral transverse capsular incision may contribute to subsequent anterolateral rotatory instability; and (3) a vertical lateral capsular incision enhances the exammation of the knee joints. ACKNOWLEDGMENT We wish to acknowledge the editorial assistance of Cynthia L. Orenberg in the preparation of this manuscript. REFERENCES 1. Johnson LL: The lateral capsular ligament complex: Anatomical and surgical considerations. Am J Sports Med , Losse RE, Johnson TR, Southwick WO. Anterior subluxation of the lateral tibial plateau A diagnostic test and operative repair. J Bone Joint Surg 60A: , Hughston JC, Andrews JR, Cross MF, et al: Classification of knee ligament instabilities. Part II. The lateral compartment. J Bone Joint Surg 58A: , Abbott LC, Carpenter WF: Surgical approaches to the knee joint. J Bone Joint Surg 27: , Smillie IS: Injuries to the Knee Joint. Fourth edition. Edmbough, Churchill Livingstone, 1971, p Pogrund H. Practical approach for lateral meniscectomy J Trauma 16: , Aufranc OE: Approach to the knee joint by release of the collateral ligaments Clin Orthop 55: , Kaplan EB Surgical approach to the lateral (peroneal) side of the knee joint. Surg Gynecol Obstet 104 : , Bruser DM. Direct approach to the lateral compartment of the knee joint J Bone Joint Surg 42B , Slocum DB, Larsen RL: Rotatory instability of the knee. Its pathogenesis and a clinical test to demonstrate it. J Bone Joint Surg 50A: , Brown CW, Odom JA, Messner DG, et al. A simplified operative approach for the lateral meniscus. Am J Sports Med 3: , 1975 COMMENTARY Dr. Arthur E. Ellison, Williamstown, Massachusetts: This is a simple paper with a limited objective. Dr. Keene and his coworkers ask a single question: Is there evidence of instability laterally as the result of lateral meniscectomy in the otherwise normal knee? To produce an answer, 20 patients meeting those criteria and operated on using Bruser s approach are compared retrospectively with 20 others whose menisci were removed from a lateral parapatellar approach. The knees are evaluated by a stress machine. The results show that there is no difference in varus instability between the two groups and as chance would have it there are four knees in each group that rate as anterior cruciate deficient. It would appear to be a standoff. However, Dr. Keene and his coworkers tell us there is somewhat more drawer and positive anterolateral rotatory instability tests for the Bruser than the lateral parapatellar route. I have precious little quarrel with any of that, especially when it is pointed out that the period of follow-up time for the Bruser procedure is 5 years as compared to 11/z years for the lateral parapatella group. Indeed, this is what we would anticipate. As we keep saymg, instability is dynamic and m the antenor cruciate-deficient knee we would certainly expect more impressive findings m 5 years than in 11/2. I also agree with their conclusions, although when they say 96

5 &dquo;in patients with absent anterior cruciate ligaments a lateral transverse capsular incision may contribute to subsequent anterolateral rotatory instability,&dquo; I must add &dquo;yes, and then again it may not.&dquo; I do not believe we really know from this study. History is always of value even in orthopaedics. Bruser published in O Donoghue was trying to convince us to repair acutely torn ligaments. The concept of rotatory instability had not been conceived. The lateral meniscectomy, especially for the meniscus with cystic degeneration, was, and is, a surgical challenge. Bruser wrote that with cystic lesions &dquo;complete closure is not necessary or possible.&dquo; How was Bruser to know that a major cause of lateral meniscal lesions was anterolateral rotatory instability. The Bruser approach is now passe. There are better ways, as Dr. Keene and his coworkers suggest to remove the lateral meniscus, permitting good visualization of the joint cavity and a harmless or even reparative approach to coincidental pathology. The paper by Dr. Keene et al. is helpful in calling attention to this. I have but one question. Many of us consider the iliotibial band and tract to be critical to normal function. Your paper barely mentions the iliotibial band. Is it not likely, or possible, in spite of parallellism of fibers that this is the structure that suffers the most with the Bruser mcision? I thank Dr. Allman and the program committee for the opportunity to discuss this paper. Authors Reply: Dr. Ellison s comments and thorough review of our paper are greatly appreciated. We do not dwell on the state of the iliotibial band after a Bruser incision because with the insertional fibers of the iliotibial band are this approach not sectioned. Theoretically, this incision does not cause postoperative instability because it does not mcrease the distance between the femoral and tibial attachments of the band. Al- we do not recommend the Bruser incision for the though reasons previously stated, we do not feel that the iliotibial band suffers functional damage from an incision that parallels its fibers. 97