Orthopedics

Case Reports 

Bilateral PCL Hypoplasia Resulting in Posterior, Posterolateral Rotatory Instability and Tears of the Lateral Meniscus Anterior Horn

Yong Seuk Lee, MD, PhD; Dong-Il Chun, MD; Min Jung Park, MD

Abstract

This article describes a case of bilateral sagged knees presenting as posterior, posterolateral rotatory instability with tears of the anterior horn of the lateral meniscus. Each knee had identical tears of the lateral meniscus anterior horn. A 42-year-old woman reported bilateral anterior knee pain and painful instability during running or jarring exercises. She reported no major trauma to her knees. Arthroscopic findings of her right knee revealed a posterior cruciate ligament that looked hypoplastic but was without acute injury, and the anterior horn of the lateral meniscus showed chronic complex tears with some degeneration. Posterior cruciate ligament reconstruction, posterolateral corner sling, and meniscal repair of the lateral meniscus anterior horn was performed on her right knee. Three months later, a similar operation was performed on her left knee. However, menisectomy was performed because the lateral meniscus anterior horn tear was in the junction of the red-white and white zones.

At 18 months postoperatively, the patient reported no symptoms and was satisfied with her results. Physical examination showed no joint line tenderness, and posterior stress radiographs on both knees showed grade I posterior instability. She showed no posterolateral subluxaion by supine dial test, and her prone dial test also improved approximately 15° on both knees. Lysholm score was 74 preoperatively and improved to 92 postoperatively.

Congenital aplasia or hypoplasia of the cruciate ligaments is a rare condition associated with various congenital longitudinal deficiencies of the lower limb.1,2 These congenital abnormalities result in morphologic changes of the femoral notch and the tibial eminence. However, the differential diagnosis is easily made between traumatic disruption and congenital absence.2

This article presents a case of bilateral posterior, posterolateral rotatory instability with tears of the lateral meniscus anterior horn. There were no other abnormalities or corresponding changes of the knee joints. The patient reported no major trauma to her knees.

A 42-year-old woman presented with bilateral anterior knee pain and painful instability during running or jarring exercises. She had no history of major trauma to her knees. Her symptoms began when she was an adolescent, but worsened 5 years prior to presentation, after the birth of her first child.

Physical examination and stress radiographs confirmed grade III posterior instability and posterolateral rotatory instability. Because she showed bilateral rotatory instability, we confirmed posterolateral rotatory instability by the palpation of posterolateral subluxation of the proximal tibia.3 Magnetic resonance imaging revealed a hypoplastic posterior cruciate ligament (PCL) and a complex tear of the lateral meniscus anterior horn in both knees (Figures 1, 2). On arthroscopy of the right knee, the PCL looked hypoplastic, with no sign of direct injury.4 However, the lateral meniscus anterior horn was torn and frayed with some degeneration.

After 3 months of conservative treatment, such as medication, strengthening, and activity modification, her symptoms did not improve. We performed a right-knee arthroscopic PCL reconstruction with a tibialis allograft using a transtibial technique, a posterolateral corner sling with a tibialis allograft using a fibula head tunnel, and concomitant meniscal repair of the lateral meniscus anterior horn using an outside-in technique because the tear site was in the red zone (Figure 3).5,6 During the follow-up period, her right knee recovered well; however, her left knee showed persistent symptoms.

Three months after the right-knee operation, arthroscopic surgery was performed on her left knee. The left knee had similar findings to the right. Arthroscopic PCL reconstruction was performed with a tibialis allograft using a transtibial technique, posterolateral corner sling with a tibialis allograft using a fibula head tunnel, and concomitant partial menisectomy of the lateral meniscus anterior horn on her left knee because the tear of lateral meniscus anterior horn…

Abstract

This article describes a case of bilateral sagged knees presenting as posterior, posterolateral rotatory instability with tears of the anterior horn of the lateral meniscus. Each knee had identical tears of the lateral meniscus anterior horn. A 42-year-old woman reported bilateral anterior knee pain and painful instability during running or jarring exercises. She reported no major trauma to her knees. Arthroscopic findings of her right knee revealed a posterior cruciate ligament that looked hypoplastic but was without acute injury, and the anterior horn of the lateral meniscus showed chronic complex tears with some degeneration. Posterior cruciate ligament reconstruction, posterolateral corner sling, and meniscal repair of the lateral meniscus anterior horn was performed on her right knee. Three months later, a similar operation was performed on her left knee. However, menisectomy was performed because the lateral meniscus anterior horn tear was in the junction of the red-white and white zones.

At 18 months postoperatively, the patient reported no symptoms and was satisfied with her results. Physical examination showed no joint line tenderness, and posterior stress radiographs on both knees showed grade I posterior instability. She showed no posterolateral subluxaion by supine dial test, and her prone dial test also improved approximately 15° on both knees. Lysholm score was 74 preoperatively and improved to 92 postoperatively.

Congenital aplasia or hypoplasia of the cruciate ligaments is a rare condition associated with various congenital longitudinal deficiencies of the lower limb.1,2 These congenital abnormalities result in morphologic changes of the femoral notch and the tibial eminence. However, the differential diagnosis is easily made between traumatic disruption and congenital absence.2

This article presents a case of bilateral posterior, posterolateral rotatory instability with tears of the lateral meniscus anterior horn. There were no other abnormalities or corresponding changes of the knee joints. The patient reported no major trauma to her knees.

Case Report

A 42-year-old woman presented with bilateral anterior knee pain and painful instability during running or jarring exercises. She had no history of major trauma to her knees. Her symptoms began when she was an adolescent, but worsened 5 years prior to presentation, after the birth of her first child.

Physical examination and stress radiographs confirmed grade III posterior instability and posterolateral rotatory instability. Because she showed bilateral rotatory instability, we confirmed posterolateral rotatory instability by the palpation of posterolateral subluxation of the proximal tibia.3 Magnetic resonance imaging revealed a hypoplastic posterior cruciate ligament (PCL) and a complex tear of the lateral meniscus anterior horn in both knees (Figures 1, 2). On arthroscopy of the right knee, the PCL looked hypoplastic, with no sign of direct injury.4 However, the lateral meniscus anterior horn was torn and frayed with some degeneration.

Figure 1A: Stress radiograph of the right knee showing loss of normal stepping Figure 1B: A thin and rudimentary PCL signal Figure 1C: A complex signal increase in the lateral meniscus anterior horn area
Figure 1: Stress radiograph of the right knee showing loss of normal stepping (A). MRI revealing a thin and rudimentary PCL signal (B) and a complex signal increase in the lateral meniscus anterior horn area (C).

Figure 2A: Stress radiograph of the left knee Figure 2B: MRI showing a similar PCL signal Figure 2C: Lateral meniscus anterior horn area
Figure 2: Stress radiograph of the left knee appearing similar to that of the right knee (A), and MRI showing a similar PCL signal (B) and lateral meniscus anterior horn area (C) to those of the right knee.

After 3 months of conservative treatment, such as medication, strengthening, and activity modification, her symptoms did not improve. We performed a right-knee arthroscopic PCL reconstruction with a tibialis allograft using a transtibial technique, a posterolateral corner sling with a tibialis allograft using a fibula head tunnel, and concomitant meniscal repair of the lateral meniscus anterior horn using an outside-in technique because the tear site was in the red zone (Figure 3).5,6 During the follow-up period, her right knee recovered well; however, her left knee showed persistent symptoms.

Figure 3A: PCL was hypoplastic Figure 3B: The lateral meniscus anterior horn was torn and frayed with some degeneration Figure 3C: Meniscal repair of the lateral meniscus anterior horn
Figure 3D: Meniscal repair of the lateral meniscus anterior horn Figure 3: On arthroscopy of right knee, the PCL was hypoplastic (A) and the lateral meniscus anterior horn was torn and frayed with some degeneration (B). An arthroscopic PCL reconstruction with a tibialis allograft (C) and meniscal repair of the lateral meniscus anterior horn using an outside-in technique (D) were performed. Abbreviations: ACL, anterior cruciate ligament; LMAH, lateral meniscus anterior horn; PCL, posterior cruciate ligament.

Three months after the right-knee operation, arthroscopic surgery was performed on her left knee. The left knee had similar findings to the right. Arthroscopic PCL reconstruction was performed with a tibialis allograft using a transtibial technique, posterolateral corner sling with a tibialis allograft using a fibula head tunnel, and concomitant partial menisectomy of the lateral meniscus anterior horn on her left knee because the tear of lateral meniscus anterior horn was in the junction of the red-white and white zones (Figure 4).5,6

Figure 4A: PCL was hypoplastic Figure 4B: The lateral meniscus anterior horn was torn and frayed with some degeneration
Figure 4C: An arthroscopic PCL reconstruction with a tibialis allograft was performed Figure 4D: An arthroscopic PCL reconstruction with a partial meniscectomy was performed
Figure 4: On arthroscopy of left knee, the PCL was also hypoplastic (A) and the lateral meniscus anterior horn was also torn and frayed with some degeneration (B). An arthroscopic PCL reconstruction with a tibialis allograft (C) and partial meniscectomy (D) were performed. Abbreviations: ACL, anterior cruciate ligament; LMAH, lateral meniscus anterior horn; PCL, posterior cruciate ligament.

For 2 to 3 weeks postoperatively, a long-leg splint was used to hold the knee in full extension. It has a posterior pad that prevented the tibia from sagging posteriorly. Straight-leg raising, quadriceps setting, and calf-raising exercises were started the day after surgery. The patient was allowed tolerable weight bearing using crutches. After 2 weeks, the splint was removed once or twice a day, and the patient was encouraged to perform passive range of motion to 30° to 90° of flexion until 6 weeks; she used both hands to support the proximal part of the tibia or performed these exercises in the prone position to prevent tibial sagging. The range of flexion was allowed to 120° by the twelfth postoperative week.7

At 18 months postoperatively, the patient reported no symptoms and was satisfied with her results. Physical examination showed no joint line tenderness, and posterior stress radiographs on both knees showed grade I posterior instability.3 She showed no posterolateral subluxaion by supine dial test, and her prone dial test also improved approximately 15° on both knees.3 Lysholm score was 74 preoperatively and improved to 92 postoperatively.

Discussion

The lateral compartment, especially the anterior side, could be a problematic site in the chronic PCL and posterolateral rotatory instability patient. Generally, with a chronic PCL injury, it is reported that main involved site is the medial and patellofemoral compartment.8

One possible interpretation of involving the anterolateral compartment is that lateral meniscus anterior horn is directly in contact with the lateral femoral condyle when the knee is extended or slightly flexed. Most daily weight-bearing activities are performed with the knee in this position. Furthermore, if a patient has a combined posterolateral rotatory instability, the lateral meniscus anterior horn could be also be loaded with a shear force because of rotatory instability. In our patient, the lateral meniscus anterior horn showed complex and degenerative tear patterns, and this finding could imply that chronic load was given to this area. Yoo et al9 reported that the compression fracture on the anteromedial side and the stretching injury on the posterolateral side together support the mechanism of hyperextension pivoting on the anteromedial side of the knee joint. They also imply that main load could be given to the anterior side of tibia. In our case, the main lesion was located at the anterolateral side and may have been due to the chronic posterolateral subluxation under the loading condition.

The classification of dysplasia of the cruciate ligaments was reported by Manner et al.2,10 Our case showed no combined lower extremities or knee abnormalities, and therefore was not included in any of the 3 main types. Some elongated fibers were observed, and this could imply a traumatic cause. However, our patient had no history of major trauma to either knee, yet both knees showed similar injury patterns. Therefore, in our opinion, this case may be a mild and rare form of dysplasia.

References

  1. Kaelin A, Hulin PH, Carlioz H. Congenital aplasia of the cruciate ligaments. A report of six cases. J Bone Joint Surg Br. 1986; 68(5):827-828.
  2. Manner HM, Radler C, Ganger R, Grill F. Dysplasia of the cruciate ligaments: radiographic assessment and classification. J Bone Joint Surg Am. 2006; 88(1):130-137.
  3. Jung YB, Lee YS, Jung HJ, Nam CH. Evaluation of posterolateral rotatory knee instability using the dial test according to tibial positioning [published online ahead of print November 28, 2008]. Arthroscopy. 2009; 25(3):257-261.
  4. Fanelli GC, Giannotti BF, Edson CJ. The posterior cruciate ligament arthroscopic evaluation and treatment. Arthroscopy. 1994; 10(6):673-688.
  5. Ahn JH, Lee YS, Chang MJ, Kum DH, Kim YH. Anatomical graft passage in transtibial posterior cruciate ligament reconstruction using bioabsorbable tibial cross pin fixation. Orthopedics. 2009; 32(2):96.
  6. Jung YB, Jung HJ, Kim SJ, et al. Posterolateral corner reconstruction for posterolateral rotatory instability combined with posterior cruciate ligament injuries: comparison between fibular tunnel and tibial tunnel techniques [published online ahead of print January 9, 2008]. Knee Surg Sports Traumatol Arthrosc. 2008; 16(3):239-248.
  7. Lee YS, Ahn JH, Jung YB, et al. Transtibial double bundle posterior cruciate ligament reconstruction using TransFix tibial fixation [published online ahead of print February 16, 2007]. Knee Surg Sports Traumatol Arthrosc. 2007; 15(8):973-977.
  8. Jung YB, Jung HJ, Tae SK, Lee YS, Yang DL. Tensioning of remnant posterior cruciate ligament and reconstruction of anterolateral bundle in chronic posterior cruciate ligament injury. Arthroscopy. 2006; 22(3):329-338.
  9. Yoo JH, Kim EH, Yim SJ, Lee BI. A case of compression fracture of medial tibial plateau and medial femoral condyle combined with posterior cruciate ligament and posterolateral corner injury [published online ahead of print September 27, 2008]. Knee. 2009; 16(1):83-86.
  10. Manner HM, Radler C, Ganger R, Grill F. Knee deformity in congenital longitudinal deficiencies of the lower extremity. Clin Orthop Relat Res. 2006; (448):185-192.

Authors

Dr Lee is from the Department of Orthopedic Surgery, Gachon University Donginceon Gil Hospital, Gachon Medical School, Gachon University, Incheon, Dr Park is from the Department of Orthopedic Surgery, Ajou University School of Medicine, Suwon, and Dr Chun is from the Department of Orthopaedic Surgery, College of Medicine, Soonchunhyang University, Seoul, Korea.

Drs Lee, Chun, and Park have no relevant financial relationships to disclose.

Correspondence should be addressed to: Dong-Il Chun, MD, Department of Orthopedic Surgery, College of Medicine, Soonchunhyang University, 22 Daesagwan-gil, Yongsan-gu, Seoul, Korea (orthochun@hosp.sch.ac.kr).

doi: 10.3928/01477447-20101021-28

10.3928/01477447-20101021-28

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