Surgeons Look For Better Ways to Repair Ruptured Elbow Ligament
There's no match for the design of the elbow as nature intended it to be. When the ulnar collateral ligament (UCL) is ruptured, reconstructing it with the same fine tuning of the intact (natural or "native") ligament is a bit of a challenge. Injuries to the UCL are most common in athletes who are involved in high-level sports activities such as overhead throwing, weight-lifting, and gymnastics.
The ulnar collateral ligament (UCL) is a thick triangular-shaped band of fibrous tissue. It connects between the bottom portion of the humerus (upper arm bone) and the upper portion of the ulna (one of the two bones in the forearm). The UCL is on the medial side of the elbow (side closest to the body).
Orthopedic surgeons have been trying for years to find a technique that can stabilize an elbow joint disrupted by a UCL rupture while still allowing for a normal arc of motion. The most commonly used procedure was developed 25 years ago by Frank Jobe,MD, a well-known surgeon. Holes are drilled through the bone and graft material is used to form a figure-of-eight loop around the bones to hold them in place.
But the Jobe technique for ulnar collateral ligament (UCL) isn't easy to do and has a few potential problems such as bone fracture and too loose or too tight graft tension. Three other methods of UCL reconstruction include the use of an interference screw, a docking procedure, and a modified docking technique that uses a device called an EndoButton
Various studies have been done using these four techniques. Loading strength has been tested for each one and compared with the intact (uninjured) ligament. None have the holding power of the normal UCL but some (e.g., docking and EndoButton) have tested out to be superior to the other two (Jobe technique, interference screws).
In an effort to find a better technique, surgeons from several clinics joined together to test out a new technique for ulnar-sided fixation. The new method combined a ZipLoop, the docking technique, and an interference screw. The ZipLoop device makes it easier to tighten or loosen the graft once it's in place.
The first set of tests was done on cadaver elbows (humans donated for study after death). The docking ZipLoop technique with fixation screw was compared with the traditional Jobe technique and against the normal, intact ligament. All graft material used to reconstruct the UCL came from allograft (donated) gracilis tendons.
The researchers were able to use a special electromagnetic tracking system to test the elbows' arc of motion under loaded and unloaded conditions. Each elbow was tested first in its intact, natural (uninjured) condition.
Then the UCL was cut to simulate an injury and testing was repeated. The surgically ruptured elbows were treated with one of the two treatment techniques being investigated (Jobe technique and ZipLoop technique). The authors provided a detailed description of all surgical techniques used in this study.
The elbows were put through their paces and data collected for both techniques. Various valgus loads (against the ligament) were applied in different positions of elbow flexion. The last test applied was to the failure point -- in other words, how much load does it take before the ligament snaps and ruptures. This final measure gives an accurate measure of stability under all conditions.
In the end, they had information on valgus load limits for natural ulnar collateral ligaments (UCLs), transected (surgically cut) UCLs, and reconstructed ligaments through the full arc of motion while loaded and unloaded. What were they able to glean from this experiment?
As was stated at the beginning: nothing works as well as the original (native) ligament. Having said that, what's the second best option when the native ligament is torn? And, in this case, how does the ZipLoop technique (with its ability to adjust the graft tension) compare with the Jobe technique?
The results showed equal results between the new combined docking/screw/ZipLoop technique and the so-called gold standard Jobe technique for this ligament. And the new technique had two distinct advantages over the Jobe technique: the new method allows for slight changes in the tension of the graft and eliminates the risk of fractures.
With this knowledge, surgeons can test out the new, novel technique to repair (reconstruct) the ulnar collateral ligament at the elbow in live patients. Patient satisfaction can be measured in terms of restored motion, reduced pain, improved function, and abilithy to return-to-sport at the preinjury level of participation. For athletes with UCL injuries, surgery that can restore ligament strength to normal and provide a stable yet flexible elbow is an important discovery!
References: Robert J. Morgan, MD, et al. A Biomechanical Evaluation of Ulnar Collateral Ligament Reconstruction using a Novel Technique for Ulnar-Sided Fixation. In The American Journal of Sports Medicine. July 2010. Vol. 38. No. 7. Pp. 1448-1454.Back