Title: Tug Lesions on the Linea Aspera in a Cadaver
Authors: Steven Sorensen, OMS2; Wade Justice, MD; Ron Walser, DPT
Introduction
Tug lesions, or cortical desmoids, are abnormal projections of bone arising due to resistance from an attached tendon. They are usually found in children and adolescents, and frequently occur bilaterally. Tug lesions commonly occur at the attachment of the adductor magnus and medial head of the gastrocnemius on the distal femur. Normally, tug lesions are asymptomatic and incidentally found on an x-ray or MRI of the knee.
The linea aspera is a pair of bony, longitudinal ridges on the posterior femur, which serve as attachment sites for the adductor muscles, quadriceps, and short head of the biceps femoris. While there is published research regarding the normal characteristics of the linea aspera, no publications were found citing tug lesions on the linea aspera. This is the report of tug lesions found on the medial lip of the linea aspera bilaterally in a cadaver.
Case Description
The donated body of a 93-year-old male, who died of congestive heart failure, was found to have abnormal bony projections on the medial lips of bilateral linea asperae. Careful dissection was performed, tendinous attachments were noted, and photos were taken of each thigh and femur. Tendons were then removed, and the linea asperae and the bony projections were measured for length, width, and thickness. Radiographs were taken and analyzed blindly by a radiologist.
The bony projections along the medial lip of the linea aspera were determined to be tug lesions. The distal attachment of the adductor longus and the proximal attachment of the vastus medialis were found on the tip of the tug lesions. The tug lesion measurements were as follows in millimeters: Length Left (L) 131.82, Right (R) 149.38, Width mean L 6.24 (2.71-11.18), R 7.38 (3.59-13.48), and Thickness mean L 4.57 (3.54-5.62), R 4.88 (4.13-5.80).
Discussion
This is the first known report of a tug lesion on the medial lip of the linea aspera. Measurements, photos, and radiographs were completed to document the characteristics of the tug lesions. There was no demographic information available to suggest a career, hobby, or genetic predisposition for the tug lesions in this unusual area. Future research could include a retrospective chart review of patients with similar tug lesions, which would allow for documentation of potential causes, as well as correlation of symptoms relating to linea aspera tug lesions.
I am one of the judges for your case study. You described future studies to confirm these findings: Would you expect this to be symptomatic? What sort of treatments could you foresee if these were symptomatic lesions?
Thank you for your questions Dr. Callan! According to Kontogeorgakos, et.al. article “Cortical Desmoid and the Four Clinical Scenarios,” published in Archives of Orthopedic Trauma Surgery (2009, 129:779-785. DOI 10.1007/s00402-008-0687-6) tug lesions are not usually symptomatic, so it cannot be assumed that these tug lesions presented with clinical symptoms. That said, a patient may have sub-clinical symptoms that, when asked specifically about soreness in the region of the tug lesion they may confirm chronic soreness.
As far as treatment, if symptomatic, stretching of the adductors (longus) and quadriceps (vastus medialis) would be indicated to attempt to reduce strain on the bony attachments. Dry needling is another modality I used as a PT which helped to reduce nociceptive stimulus to the brain and muscle tension, and would likely be very effective for the indicated muscles of these tug lesions.
Thank you for this interesting case report, Student Dr. Sorensen. I have been assigned as one of the judges for your case report. Can you tell us more about the history of these “lesions” – how were they first identified? How did they get their name? Was it because a “Dr. Tug” first identified them? Thanks again.
Dr. Briggs Early, thank you for your questions! Tug lesions have been identified primarily by radiologists on the adductor tubercle and proximal attachment of the gastrocnemius, according to Kontogeorgakos, et.al. article “Cortical Desmoid and the Four Clinical Scenarios,” published in Archives of Orthopedic Trauma Surgery (2009, 129:779-785. DOI 10.1007/s00402-008-0687-6). Tug lesions are known by multiple other names such as cortical irregularities, periosteal desmoids, parosteal-juxtacortical desmoids, and avulsive cortical irregularity. (Kontogeorgakos) Numerous other research articles and even the Taber’s Cyclopedic Medical Dictionary, 2017, do not indicate the origin of the name “tug lesions.” However, I have noticed in the research that the name is not capitalized and therefore probably not an eponym, but rather a mechanical origin, like a tendon tugging on a bone to cause the bone to extend over time. If there was a Dr. Tug, he is supremely disrespected by the use of a lower case ‘t,’ especially with a name that is much easier to pronounce than Osgood-Schlatter.
Have a great day!
LOL, very interesting, thanks so much for your thorough response!
Judge: What do you think is the possible cause for the tug lesions? Muscular stress, calcification or a possible tumor?
Dr. Novack, thank you for your questions! To answer your question, with no background on our subject, I must fall back on biomechanical principles such as Wolff’s law, which states that bone grows in proportion to mechanical stresses placed on it. As tug lesions on the linea aspera have never been recorded previously, this person must have had a rare hobby or profession, which placed extraordinary stress on the attached muscles/tendons for many years of his life. As there are not too many people who make a living on horseback, as even ranchers have advanced to side-by-side ATVs, I suspect that he was a lineman, not of the Seattle Seahawks type. With his life depending on each step on the side of a vertical pole, I have heard first hand from a lineman who complained of the chronic strain felt on their adductor muscles from years of work.
Interestingly the radiologist did note multiple “lytic lesions,” but concluded that these were not related to the tug lesions present on the bones.
Thank you and have a great day!