Anatomical study of the synovial plicae of the hip joint

Abstract

Observations and measurements of the synovial plicae of the hip joints were made on 63 embalmed cadavers. The cadavers were divided equally among three age groups (fetuses, children, and adults). Our observations showed that the plicae appeared in two forms (flat and villous) and were mainly confined to the external surface of the lower medial part of the acetabular labrum (labral plicae), the base of the ligament of the head of the femur (ligamental plicae), and along the reflecting line of the synovial membrane on the base of the femoral neck (neck plicae). The ligamental plicae were well padded with a fibroelastic pad of fat filling the acetabular fossa, and the neck plicae were far away from the articular surfaces of the joint; as a result, neither was likely to be injured or entrapped during joint movements. The labral plicae were larger than the ligamental or neck plicae and had an incidence of 73.8% in the fetal group. The fetal plicae were found only after the fetal age of 5 months. In nine cases of the child and adult groups, the labral plicae extended between the articular surface of the femoral head and the lower part of the acetabulum during medial rotation of the thigh. When the thigh was rotated laterally, the plicae in six of the same cases could be returned to their original positions. In the remaining three cases, there was continual impingement. Clin. Anat. 10:235‐238, 1997. © 1997 Wiley‐Liss, Inc.

Arthroscopic Treatment of a Symptomatic Hip Plica

“…There also were three types described by location: labral (adjacent to the inferomedial region of the acetabular labrum), ligamental (at the acetabular base of the ligament of the head of the femur), and neck (in the synovial reflection at the superior portion of the femoral neck). 7 Using this terminology, 7 the plica in the current case would be described as flat and labral.…”

“…In the study of Fu et al, 7 it was surmised that some of the structures in the cadaver specimens would be vulnerable to impingement and associated symptoms. All of the possibly symptomatic plicae were of the labral type.…”

“…However, the preponderance of attention in sports medicine has been focused on the knee, where plicae commonly are found with or without symptoms. 13,15,16 Normally plicae of the knee may slip between the articular surfaces, 7 but in some cases, plicae are present as unusually large folds that are vulnerable to impingement between the articular surfaces. Repeated minor entrapments of a plica, or one traumatic episode of entrapment, may result in what has been called a plica syndrome.…”

“…4,5,16 In the knee, diagnosis and treatment of plica syndrome are well described. 4,5,12,16,17 Other joints, including the elbow, 2,3 tibiotalar joint, 1,8,11,14 and hip 6,7,9 also are known to have synovial plicae that may become symptomatic, but to date, few cases have been reported. Regarding the hip in particular, plicae have been described in cadavers, 7 in patients having diagnostic arthroscopy, 6 and incidental findings in arthrography.…”

Frontiers in Orthopaedic Surgery 2011, Viersen-Süchteln, Germany, 17 June 2011

“…Plicae are embryologic remnants in synovial joints that are often symptomatic in the knee joint, whereas in the hip joint, reports are anecdotic. Fu et al 96 describe 3 locations for plicae: labral, ligamentous and neck plicae. The pectinofoveal fold is a band that runs parallel to the inferior neck ( Figure 11I) with an incidence of 95% in MRI and 99% in hip arthroscopy, 97 this structure should be regarded as normal and distinguished from pathologic and symptomatic plicae.…”