Lateral ligament injuries of the knee

Transcription

1 Knee Surg, Sports Traumatol, Arthrosc (1998) 6:21 25 KNEE Springer-Verlag 1998 Y. Krukhaug A. Mølster A. Rodt T. Strand Lateral ligament injuries of the knee Received: 22 January 1997 Accepted: 20 June 1997 Y. Krukhaug A. Mølster ( ) A. Rodt T. Strand Department of Orthopedic Surgery, Surgical Institute, Haukeland University Hospital, N-5021 Bergen, Norway Tel.: (47) Fax: (47) Abstract Between 1982 and patients were treated for acute lateral knee ligament injuries; 25 patients, with a median age of 25.5 (range 16 75) years at injury, appeared for follow-up. Seven patients had isolated injury of the lateral collateral ligament/capsular structures, the remaining 19 patients had concomitant ligament injuries in the knee. Eight patients were treated conservatively, 1 with plaster immobilization and 7 with early mobilization. Eighteen patients underwent surgery, 17 of these within 3 weeks of injury. Repair/reconstruction of the cruciate ligaments was done at the same time as the lateral collateral ligament repair in 10 patients. At follow-up after a median of 7.5 years (range 6 months to 13 years), 11 had no varus instability, 7 had 1+, 5 had 2+, and 2 patients had 3+ varus instability. All patients with a final result of 2+ or 3+ had combined ligament injuries. The surgically treated lateral collateral ligament injuries all had a primary instability of 2+ or more. These patients showed an improvement in varus instability from a mean of preoperatively to a mean of postoperatively. Twothirds of the surgically treated patients were stable or had a 1+ instability at follow-up. One conservatively treated patient with a 2+varus instability and 1 with 1+ showed no improvement. Five conservatively treated patients with initial varus instability of 1+ were stable at followup. One patient with a 1+ varus instability had anterior cruciate ligament (ACL) rupture. He had a primary ACL reconstruction without lateral repair. He had no varus instability at follow-up. Our study supports the notion that operation performed at an early stage in fresh injuries with a varus instability of 2+ or more gives improved stability as a final result. Conservative treatment may not be expected to give an improved stability, but is sufficient in mild varus instability (1+) without additional cruciate ligament injuries. Key words Knee ligaments Varus instability Introduction Injuries of the lateral ligaments of the knee are rare lesions, and the literature concerning these is sparse [3, 4]. Often the lateral injuries are part of more serious combined ruptures than medial ligament injuries, with concomitant lesions of anterior cruciate ligament (ACL) and/or posterior cruciate ligament (PCL). The main concept is that early operative treatment gives the best results [5, 8, 9, 11]. Hence, the main treatment in our department has been early operative repair of lateral knee ligament injuries with a varus instability of 2+ or more, while the lesser instabilities have been treated conservatively. To

2 22 evaluate the results we have performed a retrospective study of patients treated at our department from 1982 through Material and methods Twenty-eight patients were treated; 25, 14 males and 11 females, appeared at follow-up after a median of 7.5 years (range 6 months to 13.5 years). Median age at injury was 25.5 years (range years). Activity at time of injury is shown in Fig. 1. Degree of instability and concomitant injuries Fig. 1 Activity at time of injury Primary stability testing without anesthesia was performed in all patients. A 2+ or more varus instability, or difficulties in interpretation, was considered indication for testing under anesthesia or arthroscopy. One patient with a 1+ varus instability and ACL injury had this confirmed at testing under anesthesia. All other patients with varus instability given anesthetic were surgically treated. In the remaining patients with 1+ instability, further examination was found unnecessary. The patients were classified for instability according to Hughston et al. [7]. Seven patients had a varus instability of 1+, 3 had 2+, and 15 patients had 3+. Seven patients had isolated lateral ligament injuries. Nine had ACL rupture, 1 had ACL plus medial cruciate ligament (MCL) injury, 2 had PCL injury, and 5 patients had rupture of both cruciate ligaments in addition to their lateral ligament injury. Thus we had a total of 15 ACL injuries, 7 PCL injuries, and 1 MCL injury (Fig. 2). One patient had rupture of the medial meniscus, 4 of the lateral meniscus, and 2 of both menisci in the injured knee. There were 10 avulsion fractures in 7 patients. Four patients had Segond fractures. Three had avulsion of the proximal fibula, 2 had avulsion from Gerdy s tubercle, and 1 had a femoral epicondylar avulsion. Four had a lesion of the common fibular nerve, 1 of which was a total rupture. Five patients had skin lesions, but only 1 was classified as an open lesion with communication to the ligament injury and knee joint. Treatment Seventeen patients had an early operation for their lateral ligament injury, including the 15 patients with a 3+ varus instability and 2 out of 3 with 2+ varus instability. Fifteen patients were operated on within the 1st week of injury and 1 in the 2nd. One patient with a 1+ varus instability was treated with a cylinder cast for 6 weeks. Seven patients had primary mobilization, 1 of them had 2+ varus instability, and 6 had 1+. The patient with a 1+ varus instability and ACL rupture had primary operative repair of the ACL, while the lateral ligament rupture was left unrepaired. The operative technique on the lateral side of the knee was anatomical repair (suture) or refixation of each avulsed or ruptured structure (ileotibial tract, biceps tendon, lateral collateral ligament, popliteus tendon, arcuate ligament, capsule/meniscus attachment). Ligament reconstruction with transfer of tissue from other sites was not performed in the acute repairs. Eight patients with concomitant total ACL rupture were treated with primary repair, 5 with patellar tendon reconstruction, and 2 had no surgery of their ACL rupture. Of 7 with PCL rupture, 5 underwent surgery, 4 with direct repair and 1 with patellar tendon reconstruction. Repair by sutures of the cruciate ligaments was made by a modified Palmer technique [10, 11]: five to seven single U- sutures were placed through the avulsed or ruptured ligament end at somewhat different levels. Each limb of the U-suture was taken through one of two separately drilled bone channels, and tied over the bone bridge between them. Different tactics were applied for timing of surgery of the different lesions in combined injuries. Eleven patients had a concomitant (primary) repair of both the lateral ligament injury and the cruciate ligament injury: 8 with ACL, 2 with both ACL and PCL, and 1 with PCL rupture. In 4 cases the cruciate ligament repair/reconstruction was postponed several weeks after the primary lateral ligament repair: 2 with ACL and 2 with PCL injury. Follow-up Fig. 2 Concomitant ligament injuries (ACL anterior cruciate liament, MCL medial cruciate liament, PCL posterior cruciate liament) Patient records were used for primary registration of data. At follow-up, history and clinical findings were recorded on a knee sheet. Clinical knee examination was performed with emphasis on stability testing, which was performed by at least two examiners. Testing for varus instability was performed in full (hyper)extension, 10, and 30 of flexion, and the maximal joint opening registered. The difference compared with the contralateral normal knee was taken as the instability value, with 0 5 mm indicating 1+, 6 10 mm 2+, and more than 10 mm 3+ varus instability [7]. Posterior instability was tested in 70 of flexion. In addition to manual testing, the anterior instability in 20 of flexion was tested with KT The activity level pre injury and at follow-up was graded according to the Tegnér activity score. Lysholm s functional score was recorded at follow-up.

3 23 Statistics Comparison between groups was made by Fisher s exact test and the sign test. P values of 0.05 or lower were considered statistically significant. Results Two patients had complications. One patient had a deep wound infection after simultaneous lateral repair and ACL reconstruction. This was treated nonoperatively by antibiotics and regressed without further intervention. The other patient had a muscle necrosis of the calf muscles (anterior compartment) caused by a primarily overlooked vascular injury. Lateral instability In the 15 patients operated on for primary lateral (varus) instability of 3+, 4 were completely stable in varus testing at follow-up. Six patients had a 1+ and 3 a 2+ varus instability. These last 2 patients had unrepaired ruptures of one ACL and two PCL injures. Two further patients had a 3+ varus instability at follow-up, these were the 2 patients with complications. Two patients were operated on for a primary lateral instability of 2+; 1 was stable and 1 had a persistent 2+ varus instability. The unrepaired patient with a primary lateral instability of 2+ remained unstable 2+ at follow-up. Of 7 patients with an unoperated primary lateral instability of 1+, 6 were found to be completely stable on varus testing at follow-up, while 1 had a persistent 1+ varus instability. This was the patient treated with a plaster cast. The mean lateral stability for the surgically treated group before treatment was and at follow-up The difference is statistically significant (P < 0.05). In the group of conservatively treated patients mean lateral stability was on admission and at follow-up (P < 0.05). Sagittal instability at follow-up Fig. 3 Lysholm score Table 1 IKDC evaluation (A normal, B nearly normal, C abnormal, and D severely abnormal) 1. Patients subjective assessment A 7 B 7 C Symptoms A 17 B 3 C 4 3. Range of motion A 19 B 5 C 2 D 0 4. Ligament evaluation A 9 B 8 C 7 5. Final evaluation A 7 B 6 C 10 D 3 At follow-up, 4 patients had an anterior instability of 2+. One of these had a 3+ varus instability, 3 had 2+ varus instability, and 1 was stable on varus testing. Six patients had an anterior instability of 1+ at followup; 1 of them had a 3+ varus instability, 3 a 2+, 1 a 1+ and 1 was stable on varus testing. Fifteen patients had no anterior instability at follow-up; 7 of them had 1+ varus instability and 8 were stable. The patients with anterior instability had significantly higher values for varus instability than patients with no anterior instability (P < 0.001). Four patients had a posterior instability of 2+ at follow-up; 1 of them had a 3+ varus instability and 3 had a 2+ varus instability. The difference in varus instability between these patients and patients with no posterior instability was statistically significant (P < 0.05). The median Tegnér score before injury was 5 (range 2 8), and after injury 4 (range 1 7). The median Lysholm knee score was 90 (range ). For the patients with no varus instability the median score was 95 (range ). In the group with a remaining lateral instability of 1+, the median score was 91 (range ) and in the group with 2+ varus instability 87.5 (range ). The 2 patients with an end result of 3+ varus instability had 42

4 24 and 67 points, respectively. The first had significant sequelae of his vascular injury, influencing his functional score. The differences in score values between these groups were, however, not significant (Fig. 3). The IKDC evaluation results are shown in Table 1. As shown, symptoms are not very frequent and the range of motion (ROM) satisfactory. Seventeen patients have grade A or B stability. The remaining 8 patients have residual instability as described in the text. Discussion Injuries of the lateral ligaments of the knee are less frequent than ACL and MCL injuries, and most published studies are small. In a study by Grana and Janssen [5] the lateral ligament injuries comprised 16% of all ligament injuries of the knee; 19 patients had injuries of the lateral structures of 20 knees, but only 14 were followed. DeLee et al. [3, 4] found in a study of 735 patients that the lateral ligament injuries comprised 7%. In an earlier series from our department, 6 of 37 patients with posterior cruciate injuries were found to have concomitant lateral ligament injuries [12], and in another series 3 of 60 with ACL injuries [11]. Our consecutive study of 26 patients may therefore be of some interest, even in retrospect. Towne et al. [13], in a study of 17 patients, found that sports activities accounted for 65% of the lateral ligament injuries, while Grana and Janssen [5] found that sports injuries comprised only 25%, as traffic accidents were the cause in 11 of 20 injuries. The latter study is more in accordance with our figures, with 50% traffic and about 30% sports injuries. In both the present and other studies [1, 2] we find that lateral ligament injuries are often part of serious combined knee ligament injuries. In our study 19 of 26 patients had concomitant ligament injuries. In the study by Grana and Janssen [5], 14 of 20 patients had combined ligament injuries. It must be noted, however, that in our area an unknown number of less-serious injuries may have been treated outside our hospital. We found 4 injuries (15%) of the fibular nerve. Grana and Janssen [5] found 25% with this type of injury, which may also be taken as a sign of a more serious ligamentary instability, with great risk of combination with cruciate ligament injury. The end result for patients with lateral ligament injuries of the knee seems to be worse than for patients with medial ligament and ACL injuries [5, 7]. This is in accordance with the higher incidence of more forceful injury mechanisms (traffic accidents) [9], and that they are more often combined injuries, as is also the case in our study. Two-thirds (12 of 18) of our surgically treated patients, all with a preoperative varus instability of 2+ or 3+, had a good varus stability (1+ or less). The improvement in varus instability from the preoperative to postoperative period is statistically significant. The functional (Lysholm s knee score) score was good (> 84p) in 64% and excellent (> 94p) in 28% of the patients. In the study of Grana and Janssen [5], 50% of the surgically treated patients had a satisfactory result, with none or minimal pain limiting their daily activities. Full participation in sports was not a criterion for a satisfactory result. Functional score was not given. In their study, 85% of the patients had acute operative repair. Kannus [9] found that patients with serious lateral (varus) instability (2+ and 3+), without or with only partial cruciate ligament injuries, remained unstable or even got worse when treated conservatively. In our opinion, this precludes the later use of a conservatively treated control group for comparison, but may in itself constitute one such group. In our surgically treated patients, the twothirds with good stability in varus testing, therefore, are likely due to operative repair. Kannus found that even the lesser degrees of primary varus instability remained. In our study we found that the 1+ grade of instability had disappeared in all patients except 1 treated with a plaster cast. We cannot explain the difference between results in less serious injuries in our study compared with that of Kannus. The possible inaccuracies of manual testing may be part of the explanation. However, 6 cases of false-normal stability is hardly likely. The IKDC evaluation reveals a low number of normal knees. The frequency of symptoms and decrease in ROM is relatively low, leaving the residual instability as the apparent main reason for low grading. Our main results in connection with those of others support the concept that the serious lateral ligament injuries should be treated surgically, and preferably by primary repair. The published studies are, however, small and not conclusive [3, 4]. In our study it seems that sagittal instability influences the varus instability. Many of our patients were treated for their cruciate ligament injury by suture according to Palmer. This may be important for the end result on the lateral side, as we know this technique gives poorer results than reconstruction with patellar tendon tissue [6]. The influence of sagittal instability is hardly surprising, and may be interpreted as confirming that combined injuries are more difficult to treat. Combined primary reconstruction resulted in good lateral stability, if complications did not occur. In conclusion, our study reveals a high percentage of combined injuries when serious ruptures of the lateral ligament complex occur. Our study supports the main concept that serious lateral ligament injuries of the knee should be surgically treated, and that the (combined) repair should be performed primarily. Less-serious (1+ varus) injuries need not be treated surgically and should be primarily mobilized.

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