Debulking of Ligamentum Teres—A Technique to Preserve the Ligamentum in Open Reduction of DDH

The ligamentum teres (LT), which was initially considered as a vestige to supply blood to the femoral head during the early years of life, is now being recognized as a source of mechanical stability to the hip. It is 1 of the crucial factors providing stability to the ball and socket joint. Lately, many studies have focused on improving the outcomes of developmental dysplasia of the hip (DDH), with a major focus on preserving the ligamentum teres.1 LT is believed to have various mechanical and biological roles; hence an attempt should be made to preserve it whenever possible. Various methods of reconstruction of ligamentum teres have been described. Recently, techniques have been devised to repair the LT as a part of open reduction for developmental dysplasia of the hip.2,3 These could be technically challenging and can be done relatively easily through the medial approach for open reduction compared to the anterior approach. In this report, we describe a simple technique of preserving the ligamentum teres performed through the anterior approach thereby retaining the mechano-biological role of the LT in a hip joint.

TECHNIQUE

The child is placed in a supine position with a sandbag under the hip. The entire lower limb and affected hip are painted and draped to allow for free motion of the lower limb for ease of the procedure. An oblique bikini skin incision is taken. Sartorius-tensor fascia lata interval is identified by blunt dissection distally and extended proximally. Iliac apophysis with attached muscles and periosteum is elevated using straight osteotome and mallet. Then, subperiosteal dissection is continued to retract sartorius medially and tensor fascia lata laterally to expose the rectus femoris. Straight and reflected heads of the rectus femoris are identified and released. Further, the dissection is continued on the medial side to identify iliopsoas, and it is released as well with diathermy. Using a Cobb elevator, ilio-capsularis is reflected off the capsule, and a T-shaped capsulotomy is performed. Capsulotomy exposes the hip joint and ligamentum teres. Ligamentum teres is identified (Fig. 1A) and split into 2 halves (Fig. 1B) and elevated using a McDonald’s Retractor and debulked using a 15-blade starting from the femoral head-end directed towards the acetabulum (Fig. 1C, D). The inherent attachment of ligamentum teres on either end is still preserved. This provides enough space for the reduction of the femoral head into the acetabulum and has the advantage of preserving the mechano-biological role of ligamentum teres. The schematic representation of the procedure is depicted in Figure 2.

F1FIGURE 1:

A, Intra-operative clinical photograph shows hip exposed through minimally invasive Smith Peterson approach after capsulotomy to expose the ligamentum teres. B, Femoral attachment of the ligamentum teres is marked with dye before debulking. Note only one half of the ligament is marked. C, Clinical Photograph shows ligamentum teres held with forceps after detaching the femoral head attachment and after partial debulking. D, Ligamentum teres held with forceps after complete debulking.

F2FIGURE 2:

A, Schematic representation of hip joint showing proximal femur and acetabulum with dislocated hip joint with ligamentum teres hypertrophy. B, Red dotted line shows the part of LT to be debulked. C, LT is divided into 2 halves and debulked starting from the femoral end to the acetabular end. D, Reduced Hip Joint with debulked LT.

EXPECTED OUTCOMES

The ligamentum teres is a flat, pyramidal band of fibers that arises from the posteroinferior margin of the acetabular fossa, blends with the transverse ligament, and is attached posteroinferiorly to the center of the femoral head. The acetabular attachment consists of 2 bundles of fibers that gently transitions into a round ligament as it approaches and inserts into the fovea capitis. The anatomic and histological characteristics of the ligamentum teres and their vascular contributions to the femoral head have been well described. The function of the ligamentum teres remains poorly understood.1 Initially thought as a vestigial remnant that provides vascular supply to the femoral head is also known to have a “windshield wiper effect,” which helps with lubrication and nourishment of the entire joint during the hip range of motion. It has a role in the nociception and proprioception of the hip because of the presence of free nerve endings. Walker4 evaluated the mobility of the hip in fetuses, and he found that the length of the ligament did not permit the femoral head to be displaced beyond the posterior rim of the acetabulum.

Although excision of the ligamentum teres was considered the standard of care, recent studies have shown the importance of the ligamentum teres in improving the stability of the hip joint, thereby improving outcomes. With the advent of arthroscopy, the mechanical role of the ligamentum teres is now being utilized in improving outcomes in developmental dysplasia of the hip.

Li et al5 did a retrospective study of 123 hips to find out the incidence of the absence of the ligamentum teres in DDH. He Found 18.67% of hips with severe dislocation had an associated absence of the ligamentum teres. They also found the absence of the ligamentum teres was associated with severe Grade IHDI IV hips and high Tonnis angle. Wenger et al1 performed a biomechanical study on the properties of ligamentum teres in an in-vitro porcine model. Six immature porcine hips were dissected with the proximal femur, and acetabular anatomy was kept intact, isolating the ligamentum teres. They concluded that the ligamentum teres was found to have comparable properties as found to have in any other ligament found in the human body. So, preservation of the ligamentum teres rather than excising for a better deep, stable congruent reduction might help improve outcomes.

Various techniques of preservation of ligamentum teres have been described. Wenger et al2 described a surgical technique for the maintenance and transfer of the ligamentum teres in DDH through a medial approach. He described the reconstruction of the ligamentum teres by excising the medial most part, shortening and attaching the remaining part to the periosteum near the anterior margin of the transverse acetabular ligament. He used a nonabsorbable suture for children <24 months who failed the Pavlik harness or closed reduction and suture anchor when the child was older or affected by neuromuscular disorders. Youssef3 described a technique of the ligamentum teres reconstruction through a medial approach, which involves plication and partial excision of the ligament. He divided the ligamentum teres into 2 halves. One half is excised, and the other half is sutured side by side with sutures. He postulated that partial excision of the ligamentum teres minimizes its acetabulum filling effect, the creation of raw surface promotes healing of the ligament in its short new position, the side-to-side suture is stronger and stiffer than end-to-end, and it provides immediate stability with minimal risk of failure. Paez et al6 did a retrospective analysis of 38 hips treated with medial open reduction with or without reconstruction with a minimum 2-year follow-up. They concluded that it could minimize the rate of subluxation/dislocation in DDH.

However, these reconstruction techniques are technically challenging. There are no long-term studies on the outcomes of the ligamentum teres reconstruction. There are no post-reconstruction studies or second-look arthroscopic studies where we can find out whether it heals and functions well. Also, the affected dysplastic hip usually undergoes concomitant multiple procedures, thereby making it difficult to discern whether the improvement can be attributed to LT reconstruction. In this report, we describe a simple technique of preserving the Ligamentum teres, which is safe, simple, easily reproducible, and can be done through the anterior approach for open reduction of the hip. We believe that the intact half of the ligamentum teres forms a loop similar to plication on relocation of the head, and the raw surfaces aid in side-to-side healing of the ligamentum in the shortened length simulating a side-to-side plication.

COMPLICATIONS

The only complication specific to this technique is inadvertent complete excision of the ligamentum teres while debulking, which might need suturing or excision. The other complications are similar to any open reduction performed for DDH.

REFERENCES 1. Wenger D, Miyanji F, Mahar A, et al. The mechanical properties of the ligamentum teres: a pilot study to assess its potential for improving stability in children’s hip surgery. J Pediatr Orthop. 2007;27:408–410. 2. Wenger DR, Mubarak SJ, Henderson PC, et al. Ligamentum teres maintenance and transfer as a stabilizer in open reduction for pediatric hip dislocation: surgical technique and early clinical results. J Child Orthop. 2008;2:177–185. 3. Youssef AO. Medial approach open reduction with ligamentum teres partial excision and plication for the management of congenital hip dislocation. J Pediatr Orthop B. 2018;27:244–249. 4. Walker JM. Growth characteristics of the fetal ligament of the head of femur: significance in congenital hip disease. Yale J Biol Med. 1980;53:307–316. 5. Li T, Zhang M, Wang H, et al. Absence of Ligamentum Teres in Developmental Dysplasia of the Hip. J Pediatr Orthop. 2015;35:708–711. 6. Paez C, Badrinath R, Holt J, et al. Ligamentum Teres Transfer During Medial Open Reduction in Patients with Developmental Dysplasia of the Hip. Iowa Orthop J. 2021;41:47–53.

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