The layer concept for diagnosing hip was developed by Dr. Bryan Kelly of Hospital for Specialty Surgery in New York, NY. It is quite fascinating how he details four layers of diagnosis and treatment. I wish every hip patient would get this kind of evaluation. Unfortunately, that’s not the case. But, by educating ourselves, identifying and finding the care we need, many of us might get closer to the Layer Concept and the Hip Center model that Dr. Kelly advocates (see aforementioned blog post).
The article I will be referring to is a complex piece that I will do my best to explain on a FIFTH layer of patient-friendliness. Dr. Kelly starts off by saying that it is crucial to decipher the cause of a condition versus the pain generator find the proper treatment. That may seem like a no-brainer. But if it was a no-brainer to every doctor I don’t think we would see The Layer Concept laid out in writing. He states that The Layer Concept was developed to provide a systematic way of going about diagnosing hip pathology and pain. During the diagnostic process, it may be helpful to categorize the hip as structurally normal, structurally overcovered or undercovered.
Structurally normal means that all the values fall within a normal range (center edge angle, hip valgus and hip version values). The undercovered hip presents with anteversion (femoral neck leans forward compared to the rest of the femur), hip valgus (shaft of femur is bent outward in relation to the neck of the femur) or dysplastic characteristics (shallow hip socket to varying degrees). The overcovered hip can present with a CAM lesion at the neck-head junction of the femur, rim lesion (pincer), often associated with acetabular retroversion (hip socket “mouth” faces more to back and side than in normal hip), acetabular profunda or protrusio.
Now, I want to go over the four layers for basic understanding of what they entail.
CAM impingement can lead to labral tears and delamination of the hip socket at the contact site of the joint cartilage. CAM and pincer or both in combination are the most common. In Kelly’s paper other types of impingement (much less common) are also mentioned once you look closely at the paper's specific tests, for example, ischiofemoral impingement, trochanteric impingement and sub-spine (AIIS) impingement (will blog more about these separately, later).