What is Glenoid Fractures?
- Glenoid fractures can cause significant morbidity in individuals who are unfortunate enough to sustain one. Fractures involving the glenoid comprise up to 29% of all scapular fractures and occur most commonly in young males. There is a four times higher incidence in males and the average age at time of injury is 35 years. A spectrum of injury patterns exists for glenoid fractures, ranging from low energy instability events to high energy traumatic events. The management of glenoid fractures has an equally wide spectrum of options for each injury pattern.
- Shoulder instability events from lower energy mechanisms are commonly associated with glenoid rim fractures. This fracture pattern comprises roughly 75% to 85% of all glenoid fractures and is by far the most common injury pattern. Glenoid rim fractures occur when the humeral head impacts the glenoid during the act of dislocation creating a shear force on the underlying bone. Glenoid rim fractures may occur anteriorly or posteriorly secondary to anterior and posterior instability events, respectively. Common mechanisms for shoulder dislocation with a glenoid rim fracture include sports injuries (skiing, snowboarding, football, and hockey most commonly cited). motor vehicle accidents, falls, and seizures .Another culprit in glenoid rims fractures include iatrogenic fractures through suture anchor holes in the glenoid rim after labral repair.
- Most fractures that enter the glenoid fossa occur secondary to high energy mechanisms and require a larger force. The mechanism for glenoid fossa fractures is typically a direct load of the humeral head on the glenoid fossa, causing a fracture in the fossa and propagation into the scapular neck or body. Additionally, high energy glenoid fossa fractures are associated with as high as 88% additional injuries, with rib and clavicle fractures being the most common in 40% and 17% of cases respectively.
- The glenoid cavity is the segment of the lateral scapula that articulates with the head of the humerus creating the glenohumeral joint. The glenohumeral joint has a profound range of motion due to the lack of bony restraint, the large surface area of the humeral head, and the relatively small glenoid area. Stability of the joint is augmented by the fibrocartilaginous labrum, the fibrous capsule and capsular thickenings or glenohumeral ligaments, as well as the rotator cuff. Injuries to the soft tissue stabilizers can lead to instability or dysfunction; however, even small factures of the glenoid can have major implications on shoulder stability and function. In this way, fractures of the glenoid are different than many intra-articular fractures in other joints. In addition to the risk of stiffness and post-traumatic arthritis, many glenoid fractures cause long term instability in the shoulder joint which can be difficult to treat.
- As with many orthopedic procedures, there has been an evolution in minimally invasive surgical options for glenoid fractures. Traditionally, fractures of the glenoid were treated through either an open deltopectoral approach for anterior fractures or a Judet approach for posterior glenoid fracture and fractures that involve the scapular neck and spine. These approaches, while reliable, do require large incisions, softer tissue damage, and possibly longer rehabilitation times. The deltopectoral approach typically requires either splitting or partially incising the subscapularis tendon; while the Judet approach, as originally described, requires takedown of a significant amount of the posterior deltoid origin. Open approaches to glenoid fractures have seen increased rates of infection, hardware complications, and stiffness in some series. While more recent modifications to the original open approaches may minimize the iatrogenic soft tissue damage, the advent and advancement of arthroscopy has given orthopedic surgeons another tool for glenoid fracture management. While all-arthroscopic and arthroscopic-assisted fixation is not the answer for all glenoid fractures, its minimally invasive nature is enticing to surgeons and patients alike.
- Many techniques have been described for arthroscopic glenoid rim fixation. No matter the acuity of the fracture, the first step in fragment reduction is debridement of intra-articular fibrous debris or fracture hematoma to allow for fragment mobilization and reduction. Reduction can be aided with use of a blunt trocar, rasp, elevator, pin, or any number of other percutaneous tools. In fractures with a single large fragment, some advocate for the use of either bioabsorbable or metallic screws that may or may not be cannulated. While increasing fixation stiffness, metallic screws may result in impingement during post-operative motion requiring a second surgery for screw removal. A biomechanical cadaveric study did demonstrate that addition of a screw to a suture anchor-based repair significantly improved the construct load to failure.
- All-arthroscopic transosseous and suture anchor techniques have also been described. These techniques may be particularly useful in multiple or small fracture fragments. Porcellini and colleagues were the first to publish a substantial case series of 25 patients describing an all suture anchor fixation technique. The authors placed an anchor in the exposed subchondral bone in the fracture bed and passed a suture through the deep capsule tying a simple suture over the top of the osseolabral fragment. They showed no recurrent instability and a 92% satisfaction rate with only two patients having significant loss of external rotation. Another well described technique was described by Millet et al., and is known as the “bony Bankart bridge”. This double row technique places anchors in the intact subchondral bone and the deep fracture edge with suture bridge over the top of the fragment and has shown good long-term survivorship and biomechanical strength. Other techniques rely on labral repair at the superior and inferior fracture margins to approximate the bony fragment.