Objective
To study the clinical effect of arthroscopic preservation of residual fibers combined with single bundle reconstruction of posterior cruciate ligament with 7 strands of autologous N cord tendon.
Methods
In 13 patients with posterior cruciate ligament injury, single-bundle reconstruction was performed under arthroscopy using the tibial tunnel technique combined with 7-strand autologous N-cord tendon, and the residual posterior cruciate ligament fibers were preserved intraoperatively, and the grafts were fixed using suspension. The Lysholm knee function evaluation scale and Tegner lower extremity motility evaluation scale were used to assess the stability and mobility of the patients’ knee joints before and after surgery. Results All patients were followed up for 12 to 36 months (mean 23 months), and the Lysholm score was (50.20±8.32) and (87.23±4.20) before and 12 months after surgery, respectively (P<0.05), and the Tegner score was (2.03±0.33) and (4.11±0.13), respectively (P<0.05). After 12 months postoperatively, the drawer test was negative in 7 cases, positive in 5 cases of degree I, and positive in 1 case of degree II, and all affected knees had improved motor ability compared with the preoperative period.
Conclusion
Arthroscopic reconstruction of the posterior cruciate ligament using a single bundle of 7 strands of autologous N cord tendon combined with preservation of residual fibers by the transtibial tunnel technique is a reliable method to restore knee stability and function.
Posterior cruciate ligament (PCL) injuries can cause knee instability and affect the motor function of the affected knee. For simple PCL injuries, traditional treatment principles are determined by the degree of knee laxity, with surgical reconstruction advocated for those with posterior laxity of II or greater. Although there are many options for reconstructing the posterior cruciate ligament, many studies have shown good functional recovery in the early postoperative period without significant improvement in posterior laxity, so many scholars are now improving the posterior laxity by improving the surgical technique or changing the graft.
From May 2007 to February 2010, we performed single bundle reconstruction using the tibial tunnel technique combined with 7 strands of autologous N cord tendon in 13 patients with PCL injury, and achieved satisfactory clinical results by preserving the residual PCL fibers intraoperatively.
1. Data and methods
1.1 General information
There were 13 patients in this group, 11 males and 2 females; age 27-55 years old, average 40.3 years old, injury time 2-35 months, average 17 months. Two patients had medial meniscus injury and one patient had lateral meniscus injury. All patients did not have combined injuries to the posterior-lateral knee complex. The preoperative Lysholm knee function score and Tegner motor ability score were (50.20±8.32) and (2.03±0.33), respectively.
1.2 Surgical method
An oblique incision of approximately 2.5 cm in length was made medially from the tibial tuberosity to expose the goose foot, and the suture tendon membrane was incised, and the thin femoral muscle and semitendinosus tendon were explored on the medial side of the suture tendon membrane.
The length of the tendon was measured, and the 28-cm semitendinosus tendon was cut, and the tendon was braided and folded twice to form 4 strands. A 21-cm thin femoral tendon was cut and braided, and the tendon was fixed to the ventral junction of the polyethylene band, and the distal end was folded back around the polyethylene band to form 3 strands. The 4-strand semitendinosus tendon was fixed to the polyethylene band together with the 3-strand thin femoral tendon to form a 7-cm long 7-strand tendon graft. After measuring the total diameter of the grafted tendon, a pre-draw was performed with 70-100 N tension until 10 minutes before implantation of the graft, and a mark was made with absorbable thread 2 cm from each end of the polyethylene band of the graft.
A lateral anterolateral approach and a high anteromedial approach were performed for the arthroscopic knee. The lens is inserted from the lateral anterolateral approach and the instrument is inserted from the high anteromedial approach to explore the posterior cruciate ligament with limited clearance of the synovial membrane between it and the anterior cruciate ligament (ACL). The lens is inserted into the posterior medial compartment through the intercondylar recess with 90° of knee flexion and the posterior medial approach is done under supervision. Turning the lens into the posterior medial approach, the high anteromedial approach into the planer clears the posterior mediastinum, the lens is inserted across the posterior mediastinum into the posterior lateral compartment and the posterior lateral approach is made under supervision, and the PCL tibial stop is cleared from the posterior lateral approach into the planer with limited access.
From the high anteromedial approach into the tibial tunnel locator, enter the posterior chamber from between the PCL and ACL positioned 1 cm below the tibial articular surface and lateral to the midline, drill a 2.0 mm Kirschner needle, drill the tibial tunnel according to the graft diameter, tunnel at 50° to the tibial axis, and polish the inner tunnel opening with an inner tunnel file. The femoral tunnel is drilled from the high anteromedial approach to the scope and from the lateral anterolateral approach to the instrumentation, with the center point of the inner tunnel opening 12 mm from the anterior edge of the cartilage and 7 mm from the distal edge of the cartilage. the diameter of the medial portion of the tunnel is the same as the diameter of the graft and is 20 mm in length, while the diameter of the lateral portion is 4.5 mm. a 2 cm incision is made at the outer opening of the femoral tunnel to expose the bone of the medial femoral condyle. The lens is entered through a high anteromedial approach and the wire sleeve is monitored and fed into the joint through the tibial bone tunnel and pulled out of the femoral tunnel.
The polyethylene band at the graft end is threaded into the wire sleeve and pulled through the tibial tunnel into the joint cavity and then out of the femoral tunnel. The polyethylene band is pulled continuously, from the posterior lateral approach into the curved vascular clamp to lift the graft posteriorly and superiorly at the reflexion of the medial tibial tunnel, first into the articular cavity and then into the femoral tunnel until the graft is flush with the medial femoral tunnel at the marker line. The ends of the polyethylene band are threaded through the suture plate and knotted to secure the graft to the femoral end. The tibial side of the graft was threaded into the titanium button, the braided thread was tightened, and the knee was flexed and extended 15 times before the suture was tied in the 70° anterior drawer position to complete fixation of the tibial end of the ligament. A thorough intra-articular examination was performed, a drainage tube was placed, and the sutures were sutured to the sutures’ tendon membrane and incision.
1.3 Postoperative rehabilitation
Postoperatively, elastic bandages were applied and the joint cavity was drained by negative pressure for 2 days. Fixation in the fully extended knee position with a brace for 2 weeks, isometric contraction training of the quadriceps and N cord muscles, and progressive mobility training and proprioceptive training were started in the 3rd postoperative week. For 2 months postoperatively, the knee must be locked in the fully extended position with an adjustable brace at rest or when weight-bearing on the floor, and partial weight-bearing with a walker, with knee mobility controlled within 90°. At 3 months postoperatively, the forward uniform jogging training and lateral running training were started; at 6 months postoperatively, the forward variable speed running training and backward running training were started.
1.4 Follow up and statistical analysis
The Lysholm knee function score and Tegner lower extremity motility score were statistically processed by spss11.5 for Windows statistical software, and the difference was considered statistically significant at p<0.05 by paired t-test.
2, Results
All 13 patients were followed up for 12 to 36 months (mean 23 months), and the stability and functional recovery of the knee joint were understood through follow-up.
2.1 Physical examination
The drawer test was negative in 7 cases, positive in 5 cases and positive in 1 case after 12 months postoperatively. Two patients had reduced flexion mobility compared with the contralateral side after surgery, and the range of reduction was <10o in both cases, and one case had 5o extension limitation of the knee joint.
2.3 Functional evaluation
The Lysholm knee function scores were (50.20±8.32) and (87.23±4.20) preoperatively and 12 months postoperatively, respectively (P<0.05), and all patients were satisfied with the surgical results. The Tegner motor level scores were (2.03±0.33) and (4.11±0.13) preoperatively and 6 months postoperatively, respectively (P<0.05) (see Table 1), and all patients had improved motor ability compared to preoperatively.
3. Discussion
Since the diameter of the PCL is larger than that of the ACL, with its medial diameter averaging about 13 mm, we used 7 strands of the N cord tendon as the graft, which allowed us to obtain a graft diameter of 9 to 10 mm. In addition, because posterior laxity of the knee after PCL reconstruction is often associated with a decline in graft strength, excessive posterior laxity of the knee will result if the graft is under greater tension during remodeling and the graft heals in a state of continuous stretch and lengthening. Therefore, we believe that except for technical factors, securing the diameter of the graft is beneficial to enable the initial strength of the graft to be maintained.
In the case of PCL reconstruction using the transtibial tunnel technique, the geometric model suggests that the graft will be subjected to high tension as the graft bypasses the posterior tibial edge and turns anteriorly, causing the graft to rub against the posterior tibial edge in tension and causing damage to the graft, a phenomenon known as the “killer turn. This phenomenon is known as the “killer turn” and some authors believe that the posterior laxity of the knee joint after surgery can affect the surgical outcome and therefore have tried to reduce this effect by improving the surgical technique.
Berg reported in 1995 on the Tibial Inlay technique, which he believed would eliminate the “killer turn” and allow for precise anatomic positioning of the graft. However, in a clinical study, John et al. found that there was no statistical difference between the transtibial tunnel technique and the Tibial Inlay technique at more than two years postoperative follow-up, regardless of the posterior drawer test, KT-1000 functional test, or Lysholm, Tegner, and AAOS knee scores, if a single femoral stop was used, and neither technique maintained initial posterior stability. . Therefore, we continued to use the transtibial tunnel technique, but blunted the inner tibial tunnel opening intraoperatively using an endotonial file to reduce the wear of the tunnel opening on the graft.
After St¨ ahelin et al. reported in 2001 the use of a double-bundle reconstruction of the posterior cruciate ligament using the N-tendon, many studies comparing single- and double-bundle reconstruction techniques for PCL via the tibial tunnel have appeared, but no biomechanical studies have suggested a significant difference between double- and single-bundle reconstruction techniques for reconstructing knee motion function. A review of the literature by Robert et al. found that the advantages of PCL dual-beam reconstruction over single-beam reconstruction were uncertain.
However, Kim et al. found that posterior stability of the knee after arthroscopic tibial inlay double-beam reconstruction of PCL was superior to both the transtibial tunnel single-beam reconstruction technique and the arthroscopic tibial inlay single-beam reconstruction technique. Since the arthroscopic tibial inlay double-beam reconstruction PCL technique is more complicated, and the transtibial tunnel double-beam reconstruction PCL technique does not have obvious advantages, we currently still use the transtibial tunnel single-beam reconstruction PCL technique because the residual ligament fibers and their proprioceptors on the synovial membrane are beneficial to graft healing and postoperative rehabilitation, so many scholars currently advocate the use of PCL residual preservation. In our study, we found that the residual PCL fibers preserved on the tibial side are located between the posterior edge of the tibial plateau and the graft, which can play the role of a soft protective pad and may help to reduce the direct abrasion of the graft by the posterior edge of the tibial plateau, so we advocate preserving the residual PCL fibers.
In this study, we demonstrated that arthroscopic preservation of the residual fibers combined with single bundle reconstruction of the posterior cruciate ligament with 7 strands of autologous N-cord tendon by trans-tibial tunnel technique is a reliable method to restore the stability and function of the knee joint. However, because of the short follow-up period of this group of patients, their long-term results need to be further observed. As there are studies suggesting that arthroscopic tibial inlay double bundle reconstruction PCL technique can obtain better posterior stability of the knee joint [11], we want to conduct clinical studies on this surgical technique in the future.