New York—July 10, 2011
“The conclusion from this study is that you should be cautious about releasing the psoas tendon, particularly in cases where there is some structural instability in the hip, specifically increased femoral anteversion, because although the tendon may be causing pain, it is also providing some dynamic support to the hip so it can cause problems if it is released,” said Bryan T. Kelly, M.D., who led the study and is co-director of the Center for Hip Preservation (www.hss.edu/hippain) at Hospital for Special Surgery (HSS) in New York.
The study received the 2011 Herodicus Award given annually by the Herodicus Society at the AOSSM meeting for the best paper submitted by an orthopedic resident or sports medicine fellow.
The hip is a ball-and-socket joint where the head of the femur (thigh bone) rotates within the cup-shaped socket of the pelvis. The head of the femur is supported by an angled neck which joins to the long thigh bone. At the base of the femoral neck is a boney protrusion. The psoas tendon is one of two hip flexor tendons that attaches to this protrusion. When the pelvis grows faster than the psoas tendon, this tendon becomes tight and snaps over the pelvis during walking or other activity. This condition, which can be painful, is known as a snapping psoas tendon.
“The reason that it snaps usually has to do with the anatomy of the pelvis. We usually see it in adolescent hips where the pelvis is growing at a faster rate than the tendon can accommodate for the growth,” said Dr. Kelly. “Structurally the tendon is not long enough to accommodate the bony anatomy.”
Doctors usually treat a snapping psoas tendon with physical therapy that involves stretching and strengthening, anti-inflammatories and corticosteroids, but if this doesn’t work, doctors resort to surgically lengthening the tendon. Because the tendon does not have the ability to stretch, surgeons cut slits in the tendon in what is called a partial release of the tendon or a fractional lengthening. “You cut it in a way that allows the muscle to elongate,” Dr. Kelly said.
Studies have shown that arthroscopic and open surgery can achieve similar outcomes for this condition. Few studies, however, have studied whether abnormalities in hip structure, specifically femoral anteversion, can impact outcomes. In most people, the center of the femoral neck points toward the center of the hip socket. Femoral anteversion is a condition in which the center of the femoral neck leans toward the front of the socket. This causes the knee and foot on the affected side to rotate internally or twist toward the midline of the body.
In December 2006, HSS researchers started a prospective registry of all hip arthroscopy procedures performed during a three-year period, 2006 to 2009, by a single, high-volume arthroscopic hip surgeon, Dr. Kelly. The study presented at AOSSM included all patients who underwent a psoas tendon lengthening at the time of surgery, a minimum of six months follow-up, and a preoperative high-resolution computed tomography (CT) scan to detect femoral anteversion. Patients were not included in the study if they had previous tendon hip surgery or hip trauma.
Sixty-seven patients underwent arthroscopic lengthening of a symptomatic psoas tendon, either in isolation or in conjunction with treatment for hip impingement. CT scans showed that 19 of 67 patients had high anteversion. The researchers assessed clinical outcomes both before and after surgery with modified Harris Hip Score (MHHS) and Hip Outcome Score (HOS) questionnaires. These are commonly used to evaluate a patient’s ability to carry out specific activities that involve the hip: activities of daily living, such as climbing stairs, and athletic activities, such as running and jumping.
Prior to surgery, patients who had high anteversion scored significantly worse in terms of athletic activities on the HOS, but there was no difference in either questionnaire scores in terms of daily living activities. After surgery, patients who had high anteversion scored significantly worse on the MHHS questionnaire with regard to athletic and daily living activities, but the HOS scores were similar between the two groups. Twice as many patients who had high anteversion had to undergo revision surgery.
The researchers say the psoas tendon may be an important stabilizer in the hips of patients with high anteversion, and the tendon’s release in these patients may result in a delayed return to activities after surgery and inferior outcomes.
“The results of this study indicate that there are certain groups of patients that respond very favorably to surgical treatment of the psoas tendon, but there are other groups of patients that due to mechanical reasons, surgeons should exercise extreme caution in proceeding with any tendon release around the hip,” Dr. Kelly said. He said these patients should be considered for alternative treatment strategies.
Other authors of the study are lead author and orthopedic surgery resident Peter D. Fabricant, M.D., and Katrina Dela Torre, R.N., M.Sc., at HSS, and Asheesh Bedi, M.D., former HSS fellow now at the University of Michigan.
About HSS | Hospital for Special Surgery
HSS is the world’s leading academic medical center focused on musculoskeletal health. At its core is Hospital for Special Surgery, nationally ranked No. 1 in orthopedics (for the ninth consecutive year) and No. 3 in rheumatology by U.S.News & World Report (2018-2019). Founded in 1863, the Hospital has one of the lowest infection rates in the country and was the first in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center four consecutive times. The global standard total knee replacement was developed at HSS in 1969. An affiliate of Weill Cornell Medical College, HSS has a main campus in New York City and facilities in New Jersey, Connecticut and in the Long Island and Westchester County regions of New York State. In 2017 HSS provided care to 135,000 patients and performed more than 32,000 surgical procedures. People from all 50 U.S. states and 80 countries travelled to receive care at HSS. In addition to patient care, HSS leads the field in research, innovation and education. The HSS Research Institute comprises 20 laboratories and 300 staff members focused on leading the advancement of musculoskeletal health through prevention of degeneration, tissue repair and tissue regeneration. The HSS Global Innovation Institute was formed in 2016 to realize the potential of new drugs, therapeutics and devices. The culture of innovation is accelerating at HSS as 130 new idea submissions were made to the Global Innovation Institute in 2017 (almost 3x the submissions in 2015). The HSS Education Institute is the world’s leading provider of education on the topic on musculoskeletal health, with its online learning platform offering more than 600 courses to more than 21,000 medical professional members worldwide. Through HSS Global Ventures, the institution is collaborating with medical centers and other organizations to advance the quality and value of musculoskeletal care and to make world-class HSS care more widely accessible nationally and internationally.