Abstract
Background:
The purpose of this study was to describe a one-stage operation for posterior cruciate ligament reconstruction with use of an Achilles tendon-bone allograft and a posterolateral corner reconstruction with use of two different methods, with a comparison of clinical outcomes in the two groups.
Methods:
Our study included forty-six patients who had undergone posterior cruciate ligament reconstruction with use of an Achilles tendon-bone allograft and posterolateral corner reconstruction with either anatomical reconstruction of the lateral collateral ligament and popliteus tendon with use of a tibialis posterior tendon allograft (twenty-one patients; Group A) or the modified biceps rerouting tenodesis (twenty-five patients; Group B) in an alternating fashion. Patients were assessed for knee instability with use of the dial test at 30° and 90°, together with varus and posterior stress radiography.
Results:
At the two-year follow-up evaluation, although no significant difference was found on posterior stress radiography (mean and standard error, 5.7 ± 0.4 mm for Group A compared with 4.8 ± 0.4 mm for Group B), Group A showed more improvement than Group B on the dial test (16° ± 1° vs. 13° ± 1° at 30° and 17° ± 1° vs. 14° ± 1° at 90°; p = 0.001 for both) and varus stress radiography (3.6 ± 0.3 mm vs. 2.6 ± 0.3 mm; p = 0.024), in the Lysholm (29.5 ± 2.4 vs. 22.3 ± 2.3; p = 0.037) and the International Knee Documentation Committee knee scores (p = 0.041), and less terminal flexion loss (4.0° ± 1.2° vs. 8.8° ± 1.3°; p = 0.013).
Conclusions:
Combined with posterior cruciate ligament reconstruction, anatomical posterolateral corner reconstruction of the popliteus tendon and lateral collateral ligament showed better outcomes compared with the modified biceps rerouting tenodesis, although the mean differences of varus and external rotatory stability between the groups were relatively small. However, the overall difference might have been reduced by the negative value caused by overcorrection in Group B. This study demonstrated that anatomical posterolateral corner reconstruction is a reliable alternative method in addressing posterolateral corner and posterior cruciate ligament insufficiency of the knee, a finding that ideally should be tested in a randomized controlled trial.
Level of Evidence:
Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.
Combined injury of the posterior cruciate ligament (PCL) and the posterolateral corner is challenging to treat. Undiagnosed and untreated posterolateral corner insufficiency has been recognized as one of the most common causes for late failures after PCL reconstruction1-3. Although several techniques have been developed to address posterolateral corner insufficiency, no consensus on the preferred treatment has been reached4-11.
The modified biceps rerouting technique was developed to tighten the arcuate complex and to limit excessive external rotation by rerouting and fixing the biceps tendon at the isometric point, reducing iatrogenic injury to the iliotibial band with a surgical approach through the interval between the iliotibial band and biceps muscle4. While this technique is relatively simple and takes less time for a surgeon to perform than other anatomical reconstructions, it is a nonanatomical procedure and sacrifices a normal dynamic knee stabilizer. The anatomical reconstruction of the popliteus tendon and the lateral collateral ligament (LCL) can address posterolateral corner insufficiency while preserving the normal dynamic knee stabilizer; however, the procedure is complex, challenging, and time-intensive.
The purpose of the study was to describe a one-stage operation for PCL reconstruction with use of an Achilles tendon-bone allograft in association with a posterolateral corner reconstruction with use of either the anatomical reconstruction of the LCL and popliteus tendon with tibialis posterior tendon allografts (Group A) or the modified biceps rerouting tenodesis (Group B). Clinical outcomes in the groups were compared at two years after surgery.
Subjects
From January 1999 to August 2003, forty-six patients underwent posterolateral corner and PCL reconstruction and were included in this study12. Surgery was performed by the senior author (S.-J.K.). Institutional review board approval was obtained for our study.
Surgical indications included posterior translation of grade II or higher compared with the normal, contralateral knee on posterior stress radiography; concomitant posterolateral rotatory instability on the reverse pivot-shift test and >10° of external rotation instability compared with the normal, contralateral knee at 30° and 90° on the dial test; and subjective functional deficit of the patients. The exclusion criteria were (1) previous surgery on the affected knee; (2) instability of the contralateral knee; (3) isolated PCL injury without posterolateral corner insufficiency; (4) cartilage lesions of greater than grade II according to the Outerbridge classification at arthroscopy13; (5) a severe meniscal tear requiring total meniscectomy; (6) a PCL avulsion fracture; (7) multiple ligament injuries, except for a combined PCL and posterolateral corner injury; (8) varus thrust or varus malalignment; or (9) inadequate follow-up (less than twenty-four months).
The same single-bundle anterolateral transtibial PCL reconstruction was used in both groups12. For the posterolateral corner insufficiency, the patients were alternately assigned to either Group A (anatomical reconstruction group) or Group B (the modified biceps rerouting tenodesis group). After the patients were assigned to Group A or Group B, the patients with other associated intra-articular injuries were excluded.
Evaluation of Instability
Posterolateral rotatory instability was evaluated with use of the dial test for external rotatory instability and varus stress radiography for varus instability. The external rotatory instability on the dial test was measured in comparison with the axis of the medial border of the foot with that of the femur at 30° and 90° of knee flexion with the patient prone. Varus instability was measured by varus stress radiography at 30° of knee flexion with use of a Telos device (Telos, Marburg, Germany) with a 15-kPa varus load. To quantify the lateral joint opening on the varus stress radiograph, we used the method suggested by Jacobsen14, as illustrated in Figure 1. The varus laxity was graded according to the amount of side-to-side difference compared with the normal, contralateral side (grade 0 indicated <3 mm; grade 1, 3 to 5 mm; grade 2, 6 to 10 mm; and grade 3, >10 mm).
Varus stress radiography. One horizontal line tangential to the most distal subchondral bone portion of both tibial plateaus was drawn, and another horizontal line tangential to both femoral condyles was drawn in the same manner. One perpendicular line to the tibial-side horizontal line was drawn tangential to the most lateral side of the tibia. The distance between the two horizontal lines on this perpendicular line was regarded as the varus laxity.
Posterior instability was also measured by stress radiography with use of the Telos device with a 15-kPa posterior load applied to the proximal part of the tibia at 90° of knee flexion in neutral rotation. The magnitude of posterior translation was measured as described by other authors15-17 and as shown in Figure 2. To enhance the reliability in measuring the laxity in stress radiography and the dial test, two orthopaedic surgeons (T.-W.K. and S.-G.K.) independently measured the laxity twice. An individual mean value was calculated, and the mean of these individual mean values was determined. Functional outcomes were assessed with use of the Lysholm and International Knee Documentation Committee (IKDC) knee scoring scales18,19.
Posterior stress radiography. One horizontal line tangential to the tibial plateau was drawn. Then two vertical lines were drawn perpendicular to the horizontal line: one passed the midpoint between the most posterior borders of the medial and lateral femoral condyles, and the other passed the midpoint between the most posterior borders of the medial and lateral tibial plateaus. The distance between these two vertical lines was regarded as the posterior laxity.
Operative Procedure
Anterolateral Transtibial Single-Bundle PCL Reconstruction with Use of an Allogenic Achilles Tendon-Bone Graft with a One-Incision Technique
We used three unique portals in the PCL reconstruction: the parapatellar high anteromedial portal, the far anterolateral portal, and the high posteromedial portal20. The tip of the PCL guide was introduced through the parapatellar high anteromedial portal and was placed on the fossa for the PCL, located approximately 1.5 cm distal to the articular surface and just lateral to the midline when viewed from the high posteromedial portal. A skin incision was made just lateral to the tibial tuberosity, and a tibial tunnel was created on the anterolateral aspect of the tibia to reduce graft angulation on the coronal plane, as documented by Kim et al.12,21. After creating an 11-mm tibial tunnel, the tip of the guidewire for the femoral socket was introduced through the far anterolateral portal and located 7 mm posterior from the articular junction at the 10:30-o'clock position in the left knee or the 1:30 position in the right knee. To reduce graft-tunnel divergence in the femur, (1) the knee was flexed >100°, (2) the proximal part of the tibia was pushed backward as much as possible, and (3) the cannulated headed reamer was introduced through the far anterolateral portal with a plastic sheath and was pushed posteriorly to contact the lateral femoral condyle to reduce the graft angulation at the aperture of the femoral socket. An Achilles tendon-bone allograft was used. For tibial fixation, the bone plug was trimmed to 25 mm in length and 11 mm in width. The Achilles tendon was prepared to be 60 mm in length and 11 mm in width for the femoral side. The end of the Achilles tendon was threaded 30 mm in length in a whipstitch fashion, and a 9-mm EndoPearl device (Linvatec, Largo, Florida) was attached to the tip of the tendon to augment femoral fixation. After a leading suture was passed from the tibial to the femoral tunnel, the graft was introduced through the tibial tunnel and placed in the femoral socket. The graft in the femoral socket was secured with an absorbable interference screw through the far anterolateral portal at 100° of knee flexion. The graft was pretensioned by moving the knee through a full range of motion twenty times, and the tibial fixation with the absorbable interference screw was done at 70° of knee flexion by applying an anterior load to maintain the normal tibial step-off. The posterolateral corner insufficiency was addressed with use of either anatomical reconstruction of the popliteus tendon and LCL with a tibialis posterior tendon allograft (Group A) or modified biceps rerouting tenodesis (Group B).
Anatomical Reconstruction of the LCL and Popliteus Tendon with Use of a Tibialis Posterior Allograft for Posterolateral Corner Insufficiency (Group A) (Figs. 3-A Through 3-E)
A lateral incision was made from just anterior to the fibular head to the lateral femoral epicondyle with the knee extended. The interval between the posterior aspect of the iliotibial tract and the biceps tendon was developed. The lateral epicondyle of the femur, posterolateral corner of the tibia, Gerdy tubercle, and fibular head were exposed. The tip of the anterior cruciate ligament (ACL) tibial guide was placed 10 mm inferior to the knee joint line and 5 mm medial to the posterior aspect of the proximal tibiofibular joint, and the other tip was placed on the Gerdy tubercle. After the guide pin was inserted under fluoroscopic guidance, a 7-mm tibial tunnel was created. An ACL tibial guide was then placed with one tip at the point just posteromedial to the LCL insertion and the other tip at the anteroinferior aspect of the fibular head in an anteroinferior-to-posterosuperior direction at an angle of 70°. The 7-mm fibular tunnel was created in the same manner (Fig. 3-A). Each end of the tibialis posterior tendon allograft was sutured in a whipstitch fashion and passed through the tibial and fibular tunnel in an anterior-to-posterior direction with use of looped wire (Fig. 3-B). The graft was then fixed at each tunnel with a bioabsorbable interference screw (7 mm in diameter and 20 mm in length). At each free end of the graft that passed, respectively, through the tibial and fibular tunnels, a 7-mm EndoPearl device (Linvatec) was attached (Fig. 3-C). The graft from the tibial tunnel was routed to the Kirschner wire at a tentative isometric point on the anterior one-fifth of the popliteal sulcus and 15 mm distal to the femoral epicondyle. After the isometric test, a 7-mm-diameter femoral socket was created. One end of the graft (reconstructing the popliteus tendon) exiting from the tibial tunnel was introduced and secured with a bioabsorbable interference screw after pretensioning through repeated knee range of motion. The other end of the graft (reconstructing the LCL) was routed to the Kirschner wire at a tentative isometric point on the anterosuperior margin of the lateral epicondyle. After the isometric test, a femoral socket 7 mm in diameter was created, and then the other end of the graft was secured in the same manner (Figs. 3-D and 3-E).
Figs. 3-A through 3-E Anatomical reconstruction of the lateral collateral ligament (LCL) and the popliteus tendon for posterolateral corner insufficiency. Fig. 3-A The tibial and fibular tunnels were created. Fig. 3-B Each end of the graft was passed through the tibial and fibular tunnels.
Fig. 3-C After the graft was secured with a bioabsorbable interference screw at each tunnel, the EndoPearl device was attached at each end of the graft. Fig. 3-D Each end of the graft was secured in each femoral tunnel with a bioabsorbable interference screw. A solid arrow indicates the reconstructed popliteus tendon. An open arrow indicates the reconstructed LCL. Fig. 3-E Postoperative radiograph of the anatomical reconstruction of the LCL and popliteus tendon. A solid white arrow and arrowhead indicate the femoral and fibular tunnels for the reconstructed LCL. An open arrow and arrowhead indicate the femoral and tibial tunnels for the reconstructed popliteus tendon.
Modified Biceps Rerouting Tenodesis for Posterolateral Corner Insufficiency (Group B) (Figs. 4-A and 4-B)
A lateral incision was made, starting just anterior to the fibular head to the lateral femoral epicondyle with the knee extended. To isolate the tendinous portion of the biceps femoris, the muscle portion of the biceps femoris was stripped off with a periosteal elevator. The lateral femoral epicondyle was exposed in the interval between the iliotibial band and biceps femoris tendon. A 0.045-in (1.143-mm) Kirschner wire was provisionally inserted at the tentative isometric point of the anterior and proximal margin of the lateral femoral epicondyle. The isolated biceps femoris tendon was looped over the Kirschner wire, and the isometric test was performed15. The isometric point was confirmed to have <2 mm of migration of the biceps femoris tendon through a knee arc of motion from 30° flexion to full flexion. After the isometric point was confirmed, a 3.2-mm hole was made proximally from the isometric point as long as the radius of a washer (9 mm) on the rerouted biceps femoris tendon line (Fig. 4-A). After a bone bed was prepared around the hole, the biceps femoris tendon was secured with a screw and washer at the isometric point (Fig. 4-B), which was consistent with the distal edge of the washer, with the knee flexed 30°.
Figs. 4-A and 4-B Modified biceps rerouting tenodesis for posterolateral corner insufficiency. Fig. 4-A The biceps femoris tendon was secured with a screw and washer at the isometric point, which was consistent with the distal edge of the washer. Fig. 4-B Postoperative radiograph of the modified biceps rerouting tenodesis.
Postoperative Rehabilitation
The postoperative rehabilitation protocol was identical for both groups. The involved knee was protected with a hinged knee brace for seven to eight weeks. The patient was encouraged to continue isometric quadriceps strengthening and patellar mobilization exercises immediately after surgery. For the first four weeks, the knee was immobilized in extension. Protected range of motion was started as tolerated three times a day at the third postoperative week. To prevent posterior sliding of the proximal part of the tibia due to gravity, the proximal part of the tibia was supported by cotton pads that were incorporated into the brace. After the first four weeks, gradual weight-bearing with crutches and motion exercises were recommended as tolerated while an unlocked, hinged knee brace was worn. At seven to eight weeks after surgery, closed-chain exercise was allowed. At ten to twelve weeks, stationary bicycle, stair-stepping, and single-leg-stance exercises were allowed. Full flexion and squatting were allowed twelve weeks after surgery. After six months, the patients were allowed to return to their full activity and sports.
Statistical Analysis
SPSS (version 12; SPSS, Inc., Chicago, Illinois) was used for statistical analyses. Both groups were compared with use of the Mann-Whitney U test (ranked continuous data) for Lysholm knee scores and the chi-square test for the IKDC scores (categorical ordinal data). We used the Student t test to compare the side-to-side difference in posterior stress radiography with use of a Telos device, dial test, varus stress radiography, and range of motion (continuous data). The intertester reliability on the stress radiography and dial test was evaluated with use of the interclass correlation with a 95% confidence interval. The level of significance was set at p < 0.05.
Source of Funding
There was no external funding source related with this study.
There were seventeen men and four women in Group A, and nineteen men and six women in Group B. The mean age at the time of surgery was 36.1 years (range, nineteen to fifty-seven years) in Group A and 34.9 years (range, twenty-three to sixty years) in Group B. The mean duration from the time of injury to surgical treatment was 13.7 months (range, four to twenty-seven months) in Group A and 15.2 months (range, six to twenty-four months) in Group B. The injury mechanisms were sports injury (eight patients in Group A and ten in Group B), motor vehicle accidents (ten and thirteen patients, respectively), and falls (three and two patients).
Associated Abnormalities on Arthroscopy
In Group A, there were two meniscal tears treated by partial meniscectomy and three Outerbridge grade-I or II cartilage lesions. In Group B, three meniscal tears were treated by partial meniscectomy and three Outerbridge grade-I or II cartilage lesions were found. No meniscal tear required meniscal repair in either group.
Side-to-Side Difference in Posterior Stress Radiography with a Telos Device
The preoperative mean side-to-side difference (and standard error) in posterior stress radiography was 9.2 ± 0.5 mm in Group A and 8.9 ± 0.4 mm in Group B. At the two-year follow-up visit, the mean side-to-side difference was 3.5 ± 0.4 mm (intraclass correlation coefficient for intertester reliability [ICC] of 0.897) in Group A and 4.3 ± 0.4 mm (ICC of 0.882) in Group B. There was no significant difference in the posterior stress radiography between the groups at the time of the two-year follow-up (p = 0.162). The mean difference (and standard error) between the preoperative and postoperative value (preoperative value minus postoperative value) was 5.7 ± 0.4 in Group A and 4.8 ± 0.4 in Group B, and there was no difference between the groups (p = 0.128) (Table I).
Side-to-Side Difference in External Rotatory Instability on Dial Test at 30° and 90°
Preoperatively, the mean side-to-side difference (and standard error) on the dial test was 20° ± 1° in Group A and 20° ± 1° in Group B at 30° of knee flexion and 22° ± 1° and 21° ± 1°, respectively, at 90° of knee flexion. At the two-year follow-up visit, the mean side-to-side difference was 4° ± 1° (ICC of 0.679) in Group A and 7° ± 1° (ICC of 0.691) in Group B at 30° of knee flexion and 4° ± 1° (ICC of 0.664) and 7° ± 1° (ICC of 0.687), respectively, at 90° of knee flexion. Five patients (20%) in Group B showed a decrease in external rotation of —5° to 0° compared with the normal, contralateral knee, and no patient in Group A exhibited this decrease in rotation. Significant differences between the two groups were noted in both 30° (p = 0.02) and 90° (p = 0.02) of knee flexion at the time of the two-year follow-up. The mean difference (and standard error) between preoperative and postoperative values at 30° was 16° ± 1° in Group A and 13° ± 1° in Group B; the difference was significant (p = 0.001). At 90°, the mean difference was 17° ± 1° in Group A and 14° ± 1° in Group B; the difference between the groups was significant (p = 0.001) (Table II).
Side-to-Side Difference in Varus Stress Radiography at 30° with a Telos Device
The preoperative mean side-to-side difference (and standard error) in the varus stress radiography was 4.9 ± 0.4 mm in Group A and 5.0 ± 0.4 mm in Group B at 30° of knee flexion. At the two-year follow-up visit, the mean side-to-side difference was 1.2 ± 0.2 mm in Group A (ICC of 0.873) and 2.4 ± 0.3 mm in Group B (ICC of 0.896); the difference between the groups was significant (p = 0.006). The mean difference between preoperative and postoperative values was 3.6 ± 0.3 in Group A and 2.6 ± 0.3 in Group B; the difference between the groups was significant (p = 0.024) (Table III). A correction loss of >5 mm was not found in either group.
Clinical Outcomes and Range of Motion
The preoperative mean Lysholm knee score (and standard error) was 59.7 ± 2.5 in Group A and 61.2 ± 2.1 in Group B. With use of the IKDC knee scoring system, ten patients were classified as C (abnormal) and eleven patients were classified as D (severely abnormal) in Group A. Twelve patients were classified as C (abnormal) and thirteen patients were classified as D (severely abnormal) in Group B. At the two-year follow-up visit, the mean Lysholm knee score improved to 89.1 ± 1.4 in Group A and 82.7 ± 2.0 in Group B; the difference between the groups was significant (p = 0.016). The mean difference between preoperative and postoperative values was 29.5 ± 2.4 in Group A and 22.3 ± 2.3 in Group B; the difference between the groups was significant (p = 0.037) (Table IV). The IKDC knee score also improved in both groups; sixteen patients (76%) were classified as normal (A) or nearly normal (B) in Group A and ten patients (40%) were classified as normal or nearly normal in Group B. There was also a significant difference between the groups (p = 0.041) (Table V).
With regard to the range of motion, no patient had preoperative limitation of motion in either group. The mean side-to-side difference (and standard error) in the limitation of terminal flexion angles at the two-year follow-up was 4.0° ± 1.2° in Group A and 8.8° ± 1.3° in Group B; the difference between the groups was significant (p = 0.013). Six patients had >15° of terminal flexion loss, including one patient (5%) in Group A and five patients (20%) in Group B (Table VI). No patient showed a lack of knee extension in either group.
Complications
In Group A, the fibular head developed a cortical break in one patient during the posterolateral corner reconstruction while the fibular tunnel was being secured with a bioabsorbable interference screw. The affected knee was immobilized for six weeks, longer than usually required.
In Group B, one patient had a transient peroneal nerve palsy that resolved spontaneously three months after surgery. Two patients with a loss of correction of >10° in external rotatory instability underwent revision surgery, and a ruptured biceps femoris tendon with pressure necrosis by the screw washer was found in both.
For posterolateral corner injuries of the knee, persistent posterolateral pathological laxity can lead to failure of the reconstructed cruciate ligament. Numerous techniques addressing posterolateral corner insufficiency have been developed: advancement of posterolateral structures, biceps tenodesis, and anatomical reconstructions4-11,22. Although biomechanical studies have compared different techniques of posterolateral corner reconstruction, few have compared their clinical outcomes10,23-25. In the current study, posterolateral corner insufficiency was addressed by either anatomical reconstruction of the LCL and popliteus tendon with a tibialis posterior tendon allograft (Group A) or the modified biceps rerouting technique (Group B); PCL insufficiency was addressed with use of the same anterolateral transtibial single-bundle PCL reconstruction with an Achilles tendon-bone allograft in both groups.
Clancy and Sutherland reported the biceps tenodesis for posterolateral corner insufficiency7, which recreated the LCL and tightened the arcuate complex. However, Fanelli et al. reported that 71% of their patients with posterolateral corner insufficiency experienced overcorrection with use of the Clancy technique26. Therefore, we modified this technique to avoid overcorrection with fine-tuning for the LCL isometric point4. This modified biceps tendon rerouting tenodesis also decreases the risk of damage to the iliotibial band by using an approach to the lateral femoral epicondyle through the interval between the iliotibial band and the biceps muscle. While it is a simple procedure and takes only a short time, reconstruction of the LCL alone may be insufficient for withstanding external rotatory instability, as it does not reproduce the popliteus tendon or popliteofibular ligament.
Investigators have found that the popliteus muscle-tendon unit (popliteus tendon and popliteofibular ligament) and the LCL are the principal structures for resisting external rotatory and varus instability27-30. The anatomical reconstruction of the posterolateral corner employed in the current study reestablishes the LCL and popliteus tendon component with use of the tibialis posterior allograft. Many authors have placed an emphasis on the popliteofibular component in addressing the external rotatory instability as it has a greater moment arm9,31. However, considering that the popliteus tendon biomechanically resists external rotatory instability as much as the popliteofibular ligament32,33, the reconstruction of the popliteus tendon has two advantages over that of the popliteofibular ligament. First, whereas the popliteofibular ligament reconstruction should be conducted on the premise that the proximal tibiofibular joint is intact, the popliteus tendon reconstruction on the tibia is not affected by the instability of the proximal tibiofibular joint. Second, the popliteus tendon reconstruction is not affected by the fibular head position31. In the comparison of Group A and Group B in the current study, there was no significant difference with regard to improvement in the side-to-side difference in the posterior stress radiography. However, comparing the posterolateral instability, including the dial test at 30° and 90° and varus stress radiography, we found significantly better improvements in Group A. On the dial test at 30° and 90°, the overall mean difference was only 2° to 3° and it may not seem to be clinically important. However, the overall difference might have been reduced by the negative value caused by overcorrection (20%) in Group B.
Group B included five patients (20%) who experienced correction loss (>10° on the dial test at 30° and 90°), but Group A had only one patient (5%) with this loss. With varus stress radiography, their overall mean difference may not appear to be clinically important despite the significant difference. However, Group A had only one patient (5%) compared with nine patients (36%) in Group B who had >3 mm of side-to-side difference.
In the assessment of the clinical outcomes, the IKDC and Lysholm knee scores of Group A were better than those of Group B. With regard to the side-to-side difference in terminal flexion, a significant difference was also found. Five patients (20%) showed >15° of terminal flexion loss in Group B, but only one patient (5%) had this loss in Group A. The modified biceps rerouting technique is not an anatomical reconstruction. Rerouting the biceps femoris tendon aims to tighten the posterolateral structure indirectly to decrease the posterolateral laxity but has an inherent possibility of overcorrection that may result in terminal flexion loss. From our results, the outcomes of Group A were more satisfactory than those of Group B.
While authors have reported promising clinical results using biceps tenodesis combined with PCL reconstruction, several points of concern were raised7,26,34. In their cadaveric study, Wascher et al.35 documented that biceps tenodesis overstrained or limited tibial external rotation, and this was consistent with the relatively high overcorrection rate (70%) in the studies by Fanelli et al.26 and Fanelli and Edson34. In the current study, although we performed an isometric test for the biceps rerouting tenodesis and improved the overcorrection rate compared with previous studies, the rate of overcorrection was still 20%. The modified biceps rerouting tenodesis cannot reestablish the principal structure of the posterolateral corner, i.e., the popliteus complex (resisting external rotatory laxity) and the LCL (resisting varus laxity). Noyes et al. investigated the causes of failure in posterolateral operative procedures and reported that the most common cause was nonanatomical graft reconstruction36. The reestablishment of the key structures is imperative in addressing posterolateral corner insufficiency.
This study has limitations. First, although the patients were alternately assigned to each group, assignment was not randomized. Second, the dial test has inherent limitations in terms of precision and reproducibility. Although two orthopaedic surgeons measured the laxity twice and the mean of their individual means was determined, the measurement of external rotatory instability by the dial test was not quantified with use of instruments such as stress radiography. Third, this study has a relatively low power for statistical analysis, given the total number of included patients, and means and standard errors of variables. Thus, the authors might make an erroneous conclusion based on a relatively small number of patients, especially with regard to the finding of no difference in posterior stress radiography between groups. In conclusion, the anatomical posterolateral corner reconstruction of the popliteus tendon and LCL combined with PCL reconstruction showed satisfactory outcomes in terms of clinical assessments, range of motion, overcorrection rate, and stress radiography compared with the modified biceps rerouting tenodesis with PCL reconstruction, although the mean differences of the varus and external rotatory stability between groups was not great. This study demonstrated that anatomical posterolateral corner reconstruction is a reliable alternative method for addressing posterolateral corner and PCL insufficiency of the knee, although this should best be confirmed in a randomized controlled trial.
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