CASE REPORT
Symptomatic Accessory Medial Meniscus Associated With Popliteal Pterygium Syndrome Shawn S. Funk, MD,* J. Jake Block, MD,w Jeffrey E. Martus, MD, MS,z and Jonathan G. Schoenecker, MD, PhDz
Background: Anomalies of the meniscus are uncommon. These anomalous formations have been predominately described in the lateral compartment of the knee. Congenital abnormalities of the medial meniscus are rare. Methods: Chart and radiographic review of a single patient with a symptomatic congenital abnormality of the medial meniscus. Results: The patient was a 5-year-old boy with popliteal pterygium who developed painful snapping in the medial knee after anterior hemiepiphyseodesis to improve his knee extension. The patient had achieved full-knee extension from a preoperative 45degree flexion contracture. The newly developed snapping was attributed to the hemiepiphyseodesis implants. After implant removal, the snapping persisted and was localized at the medial joint line. Through an arthrotomy, a medial meniscus abnormality was identified and excised with resolution of symptoms. Conclusions: This report describes a symptomatic congenital abnormality of the medial meniscus in a child with popliteal pterygium. The patient was treated with excision of the anomalous structure with complete resolution of the symptoms. This is the first report of an intra-articular knee anomaly associated with popliteal pterygium syndrome. Key Words: accessory meniscus, popliteal pterygium, anterior hemiepiphyseodesis (J Pediatr Orthop 2015;35:e76–e79)
BACKGROUND Congenital or developmental anomalies of the meniscus are relatively rare. The most common anomaly is a discoid meniscus; other variations include partial or complete absence, double-layering, and abnormal band formation.1–6 These anomalous formations have been primarily described in the lateral compartment of the knee with few anomalous formations in the medial comFrom the *Medical Center East, Vanderbilt Orthopaedic Institute; zMonroe Carell Jr. Children’s Hospital at Vanderbilt; and wVanderbilt Department of Radiology, Nashville, TN. No funding/support received for this project. The authors declare no conflicts of interest. Reprints: Jonathan G. Schoenecker, MD, PhD, Monroe Carell Jr. Children’s Hospital at Vanderbilt, 2200 Children’s Way, Suite 4202, Nashville, TN 37232-9565. E-mail: [email protected]. Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
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partment.1,7,8 An accessory meniscus is extraordinarily rare, and may be associated with pain.9 Similar structures have been reported in other case reports7,10; however, there are no reports of an accessory medial meniscus. In addition, there are no descriptions of intra-articular or meniscal abnormalities associated with popliteal pterygium in the literature.11,12
CASE PRESENTATION A 3-year-old male with pterygium syndrome and right popliteal pterygium had undergone posterior release with zplasties and split thickness skin grafting at another institution 2 years earlier for a 90-degree knee flexion contracture. He had not had specific genomic testing. The family reported that the knee flexion contracture had gradually worsened since the procedure and his ambulatory function was declining. Physical examination was notable for previous scars from the proximal thigh to the heel cord and a skin graft harvest site on the anterolateral thigh. He had a 45-degree knee flexion contracture with active knee range of motion from 45 to 110 degrees. He ambulated with a flexed knee gait. Magnetic resonance imaging (MRI) was obtained for surgical planning. This demonstrated that the sciatic nerve was immediately subcutaneous in the popliteal region. The MRI also demonstrated a large 2-part anterior meniscus, representing the anterior horn of the medial meniscus and an anomalous structure (Fig. 1), although this was not initially recognized. Treatment options were discussed with the family and growth modulation was selected. Anterior hemiepiphysiodesis was performed using 8-plates (Orthofix, Lewisville, TX) and followed by serial extension casting. Eighteen months after hemiepiphysiodesis, full extension of the knee was obtained with flexion to 90 degrees. Although range of motion improved, there were new painful mechanical symptoms of the knee, which were attributed to the implants (Fig. 2). The patient was scheduled for implant removal. Under general anesthesia, the implants were removed through the prior single midline anterior incision; however, the snapping remained palpable over the medial joint line of the knee with passive range of motion. Given the persistent mechanical abnormality, a longitudinal incision was made directly medial over the joint line. Dissection was carried to the joint capsule and the capsule was incised transversely, superior to the meniscus. A thick band of fibrocartilaginous tissue was identified. With passive knee flexion and extension, this abnormal band snapped back and forth over the medial femoral condyle. The anomalous structure had an intracapsular origin on the medial aspect of the medial condyle distal to the epicondyle. The structure then traversed the medial compartment towards the intercondylar notch (Fig. 3A).
J Pediatr Orthop
Volume 35, Number 7, October/November 2015
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Pediatr Orthop
Volume 35, Number 7, October/November 2015
Symptomatic Accessory Medial Meniscus
The abnormal tissue was released from the medial condyle (Fig. 3B) and traction was applied to free limb. The anterior knee incision was extended distally and a medial parapatellar arthrotomy was created. The lateral attachment of the anomalous structure was then identified just medial to the anterior cruciate ligament tibial origin within the intercondylar notch. The lateral attachment was incised and the abnormal structure was removed. The compartment was then reevaluated and the remaining medial meniscus appeared structurally normal (Fig. 3C). No further snapping of the knee was noted with range of motion. This anomalous structure was sent for histopathologic analysis with a subsequent diagnosis of fibrocartilage consistent with meniscal tissue (Fig. 3D).
DISCUSSION FIGURE 1. Magnetic resonance imaging of the knee before anterior hemiepiphyseodesis. The inset is a zoomed view of the anterior knee demonstrating the 2 meniscal structures overlapping. The anomalous band had a meniscal appearance by gross inspection. The medial meniscus was visualized with a grossly normal appearance, without tears, and in normal anatomic location.
Congenital or developmental meniscal abnormalities similar to this case have not been reported in the medial compartment. This case is unique because of the identification of a substantial anomaly of the medial meniscus and the subsequent development of mechanical symptoms following guided growth of the distal femur. There are no normal intra-articular structures that could have been altered by guided growth to explain the development of the anomalous meniscus. This structure was not consistent with an intra-articular plica by anatomic location, gross inspection, or histopathology. In retrospect, the anomalous meniscus
FIGURE 2. A, Lateral radiograph of the knee before hemiepiphyseodesis. B, Lateral radiograph of the knee at completion of growth modulation. Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
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Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
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J Pediatr Orthop
Funk et al
Volume 35, Number 7, October/November 2015
FIGURE 3. A, The accessory meniscus at its insertion, with its capsular expansion held by the right-angled clamp. B, The accessory meniscus is released from its medial insertion. C, Following excision of the accessory meniscus, with the * denoting the normal meniscus. D, Image of the resected accessory meniscus.
FIGURE 4. Illustration of the accessory medial meniscus described in this case.
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Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Pediatr Orthop
Volume 35, Number 7, October/November 2015
was visible on the MRI before the hemiepiphysiodesis procedure (Fig. 1). The alteration of the distal femoral anatomy to an extension deformity by the growth modulation may have permitted the abnormal meniscal tissue to produce a mechanical snap during range of motion. This congenital abnormality of the medial meniscus does not represent the previously reported double-layering or duplication of the normal lateral meniscus as the origin was distal to the medial epicondyle. There also were no tears within the normal medial meniscus. The most similar anomalous meniscus described is that reported by Bailey and Blundel.9 The accessory lateral meniscus in that case originated from a point distal to the lateral epicondyle and traversed the lateral compartment to the anterior horn of the lateral meniscus. Given this previous description, the structure identified in this case report may be best described as an accessory medial meniscus, as its anatomic attachments correspond to those of the accessory lateral meniscus. The accessory medial meniscus noted in this case is an anomaly associated with a popliteal pterygium that has not been previously reported. The structure was intra-articular with an intracapsular origin distal to the medial femoral epicondyle and an insertion medial to the tibial footprint of the anterior cruciate ligament (Fig. 4). Excision of this accessory medial meniscus resulted in resolution of the symptoms.
Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
Symptomatic Accessory Medial Meniscus
REFERENCES 1. Clark CR, Ogden JA. Development of the menisci of the human knee joint. Morphological changes and their potential role in childhood meniscal injury. J Bone Joint Surg Am. 1983;65: 538–547. 2. Komatsu N, Yamamoto K, Chosa E. Bilateral congenital separation of the lateral meniscus. A case report. Knee. 2008;15:330–332. 3. Giordano B, Goldblatt J. Abnormal band of lateral meniscus. Orthopedics. 2009;32:51. 4. Lee KW, Yang DS, Choy WS. Dislocated double-layered lateral meniscus mimicking the bucket-handle tear. Orthopedics. 2013;36:e1333–e1335. 5. Tetik O, Doral MN, Atay OA, et al. Partial deficiency of the lateral meniscus. Arthroscopy. 2003;19:E42. 6. Karataglis D, Dramis A, Learmonth DJ. Double-layered lateral meniscus. A rare anatomical aberration. Knee. 2006;13:415–416. 7. Karahan M, Erol B. Accessory lateral meniscus: a case report. Am J Sports Med. 2004;32:1973–1976. 8. Ahmed Ali R, McKay S. Familial discoid medial meniscus tear in three members of a family: a case report and review of literature. Case Rep Orthop. 2014;2014:5. 9. Bailey WH, Blundell T. An unusual abnormality affecting both knee joints in a child. Case report. J Bone Joint Surg Am. 1974;56:814–816. 10. Saygi B, Yildirim Y, Senturk S, et al. Accessory lateral discoid meniscus. Knee Surg Sports Traumatol Arthrosc. 2006;14:1278–1280. 11. Parikh SN, Crawford AH, Do TT, et al. Popliteal pterygium syndrome: implications for orthopaedic management. J Pediatr Orthop B. 2004;13:197–201. 12. Herold HZ, Shmueli G, Baruchin AM. Popliteal pterygium syndrome. Clin Orthop Relat Res. 1986;209:194–197.
www.pedorthopaedics.com |
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
e79
Symptomatic Accessory Medial Meniscus Associated With Popliteal Pterygium Syndrome Shawn S. Funk, MD,* J. Jake Block, MD,w Jeffrey E. Martus, MD, MS,z and Jonathan G. Schoenecker, MD, PhDz
Background: Anomalies of the meniscus are uncommon. These anomalous formations have been predominately described in the lateral compartment of the knee. Congenital abnormalities of the medial meniscus are rare. Methods: Chart and radiographic review of a single patient with a symptomatic congenital abnormality of the medial meniscus. Results: The patient was a 5-year-old boy with popliteal pterygium who developed painful snapping in the medial knee after anterior hemiepiphyseodesis to improve his knee extension. The patient had achieved full-knee extension from a preoperative 45degree flexion contracture. The newly developed snapping was attributed to the hemiepiphyseodesis implants. After implant removal, the snapping persisted and was localized at the medial joint line. Through an arthrotomy, a medial meniscus abnormality was identified and excised with resolution of symptoms. Conclusions: This report describes a symptomatic congenital abnormality of the medial meniscus in a child with popliteal pterygium. The patient was treated with excision of the anomalous structure with complete resolution of the symptoms. This is the first report of an intra-articular knee anomaly associated with popliteal pterygium syndrome. Key Words: accessory meniscus, popliteal pterygium, anterior hemiepiphyseodesis (J Pediatr Orthop 2015;35:e76–e79)
BACKGROUND Congenital or developmental anomalies of the meniscus are relatively rare. The most common anomaly is a discoid meniscus; other variations include partial or complete absence, double-layering, and abnormal band formation.1–6 These anomalous formations have been primarily described in the lateral compartment of the knee with few anomalous formations in the medial comFrom the *Medical Center East, Vanderbilt Orthopaedic Institute; zMonroe Carell Jr. Children’s Hospital at Vanderbilt; and wVanderbilt Department of Radiology, Nashville, TN. No funding/support received for this project. The authors declare no conflicts of interest. Reprints: Jonathan G. Schoenecker, MD, PhD, Monroe Carell Jr. Children’s Hospital at Vanderbilt, 2200 Children’s Way, Suite 4202, Nashville, TN 37232-9565. E-mail: [email protected]. Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
e76 | www.pedorthopaedics.com
partment.1,7,8 An accessory meniscus is extraordinarily rare, and may be associated with pain.9 Similar structures have been reported in other case reports7,10; however, there are no reports of an accessory medial meniscus. In addition, there are no descriptions of intra-articular or meniscal abnormalities associated with popliteal pterygium in the literature.11,12
CASE PRESENTATION A 3-year-old male with pterygium syndrome and right popliteal pterygium had undergone posterior release with zplasties and split thickness skin grafting at another institution 2 years earlier for a 90-degree knee flexion contracture. He had not had specific genomic testing. The family reported that the knee flexion contracture had gradually worsened since the procedure and his ambulatory function was declining. Physical examination was notable for previous scars from the proximal thigh to the heel cord and a skin graft harvest site on the anterolateral thigh. He had a 45-degree knee flexion contracture with active knee range of motion from 45 to 110 degrees. He ambulated with a flexed knee gait. Magnetic resonance imaging (MRI) was obtained for surgical planning. This demonstrated that the sciatic nerve was immediately subcutaneous in the popliteal region. The MRI also demonstrated a large 2-part anterior meniscus, representing the anterior horn of the medial meniscus and an anomalous structure (Fig. 1), although this was not initially recognized. Treatment options were discussed with the family and growth modulation was selected. Anterior hemiepiphysiodesis was performed using 8-plates (Orthofix, Lewisville, TX) and followed by serial extension casting. Eighteen months after hemiepiphysiodesis, full extension of the knee was obtained with flexion to 90 degrees. Although range of motion improved, there were new painful mechanical symptoms of the knee, which were attributed to the implants (Fig. 2). The patient was scheduled for implant removal. Under general anesthesia, the implants were removed through the prior single midline anterior incision; however, the snapping remained palpable over the medial joint line of the knee with passive range of motion. Given the persistent mechanical abnormality, a longitudinal incision was made directly medial over the joint line. Dissection was carried to the joint capsule and the capsule was incised transversely, superior to the meniscus. A thick band of fibrocartilaginous tissue was identified. With passive knee flexion and extension, this abnormal band snapped back and forth over the medial femoral condyle. The anomalous structure had an intracapsular origin on the medial aspect of the medial condyle distal to the epicondyle. The structure then traversed the medial compartment towards the intercondylar notch (Fig. 3A).
J Pediatr Orthop
Volume 35, Number 7, October/November 2015
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Pediatr Orthop
Volume 35, Number 7, October/November 2015
Symptomatic Accessory Medial Meniscus
The abnormal tissue was released from the medial condyle (Fig. 3B) and traction was applied to free limb. The anterior knee incision was extended distally and a medial parapatellar arthrotomy was created. The lateral attachment of the anomalous structure was then identified just medial to the anterior cruciate ligament tibial origin within the intercondylar notch. The lateral attachment was incised and the abnormal structure was removed. The compartment was then reevaluated and the remaining medial meniscus appeared structurally normal (Fig. 3C). No further snapping of the knee was noted with range of motion. This anomalous structure was sent for histopathologic analysis with a subsequent diagnosis of fibrocartilage consistent with meniscal tissue (Fig. 3D).
DISCUSSION FIGURE 1. Magnetic resonance imaging of the knee before anterior hemiepiphyseodesis. The inset is a zoomed view of the anterior knee demonstrating the 2 meniscal structures overlapping. The anomalous band had a meniscal appearance by gross inspection. The medial meniscus was visualized with a grossly normal appearance, without tears, and in normal anatomic location.
Congenital or developmental meniscal abnormalities similar to this case have not been reported in the medial compartment. This case is unique because of the identification of a substantial anomaly of the medial meniscus and the subsequent development of mechanical symptoms following guided growth of the distal femur. There are no normal intra-articular structures that could have been altered by guided growth to explain the development of the anomalous meniscus. This structure was not consistent with an intra-articular plica by anatomic location, gross inspection, or histopathology. In retrospect, the anomalous meniscus
FIGURE 2. A, Lateral radiograph of the knee before hemiepiphyseodesis. B, Lateral radiograph of the knee at completion of growth modulation. Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
www.pedorthopaedics.com |
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
e77
J Pediatr Orthop
Funk et al
Volume 35, Number 7, October/November 2015
FIGURE 3. A, The accessory meniscus at its insertion, with its capsular expansion held by the right-angled clamp. B, The accessory meniscus is released from its medial insertion. C, Following excision of the accessory meniscus, with the * denoting the normal meniscus. D, Image of the resected accessory meniscus.
FIGURE 4. Illustration of the accessory medial meniscus described in this case.
e78 | www.pedorthopaedics.com
Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Pediatr Orthop
Volume 35, Number 7, October/November 2015
was visible on the MRI before the hemiepiphysiodesis procedure (Fig. 1). The alteration of the distal femoral anatomy to an extension deformity by the growth modulation may have permitted the abnormal meniscal tissue to produce a mechanical snap during range of motion. This congenital abnormality of the medial meniscus does not represent the previously reported double-layering or duplication of the normal lateral meniscus as the origin was distal to the medial epicondyle. There also were no tears within the normal medial meniscus. The most similar anomalous meniscus described is that reported by Bailey and Blundel.9 The accessory lateral meniscus in that case originated from a point distal to the lateral epicondyle and traversed the lateral compartment to the anterior horn of the lateral meniscus. Given this previous description, the structure identified in this case report may be best described as an accessory medial meniscus, as its anatomic attachments correspond to those of the accessory lateral meniscus. The accessory medial meniscus noted in this case is an anomaly associated with a popliteal pterygium that has not been previously reported. The structure was intra-articular with an intracapsular origin distal to the medial femoral epicondyle and an insertion medial to the tibial footprint of the anterior cruciate ligament (Fig. 4). Excision of this accessory medial meniscus resulted in resolution of the symptoms.
Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
Symptomatic Accessory Medial Meniscus
REFERENCES 1. Clark CR, Ogden JA. Development of the menisci of the human knee joint. Morphological changes and their potential role in childhood meniscal injury. J Bone Joint Surg Am. 1983;65: 538–547. 2. Komatsu N, Yamamoto K, Chosa E. Bilateral congenital separation of the lateral meniscus. A case report. Knee. 2008;15:330–332. 3. Giordano B, Goldblatt J. Abnormal band of lateral meniscus. Orthopedics. 2009;32:51. 4. Lee KW, Yang DS, Choy WS. Dislocated double-layered lateral meniscus mimicking the bucket-handle tear. Orthopedics. 2013;36:e1333–e1335. 5. Tetik O, Doral MN, Atay OA, et al. Partial deficiency of the lateral meniscus. Arthroscopy. 2003;19:E42. 6. Karataglis D, Dramis A, Learmonth DJ. Double-layered lateral meniscus. A rare anatomical aberration. Knee. 2006;13:415–416. 7. Karahan M, Erol B. Accessory lateral meniscus: a case report. Am J Sports Med. 2004;32:1973–1976. 8. Ahmed Ali R, McKay S. Familial discoid medial meniscus tear in three members of a family: a case report and review of literature. Case Rep Orthop. 2014;2014:5. 9. Bailey WH, Blundell T. An unusual abnormality affecting both knee joints in a child. Case report. J Bone Joint Surg Am. 1974;56:814–816. 10. Saygi B, Yildirim Y, Senturk S, et al. Accessory lateral discoid meniscus. Knee Surg Sports Traumatol Arthrosc. 2006;14:1278–1280. 11. Parikh SN, Crawford AH, Do TT, et al. Popliteal pterygium syndrome: implications for orthopaedic management. J Pediatr Orthop B. 2004;13:197–201. 12. Herold HZ, Shmueli G, Baruchin AM. Popliteal pterygium syndrome. Clin Orthop Relat Res. 1986;209:194–197.
www.pedorthopaedics.com |
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
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