Kwak, Jae‐Man

Background This study aimed to validate the concept of notching of the ulna component of the first-generation latitude total elbow prosthesis to reduce the rate of aseptic loosening and improve implant survival. Methods A total of 18 total elbow arthroplasty cases were performed between June 2001 and May 2002 using the latitude first-generation ulnar stem. A total of 14 cases with at least 2 years of follow-up were evaluated following the exclusion of four infected cases. The senior author roughened the stem surface with notches in 10 cases (notched group) to prevent loosening. The effects of notching on implant failure were retrospectively analyzed. Results Average participant age and follow-up were 56 ± 20 years and 72 ± 44 months, respectively. The notched and unnotched implant groups were demographically equivalent. 3/4(75%) of unnotched group implants failed due to aseptic loosening. 1/10(10%) of the notched group implants failed. All unnotched group aseptic loosening cases occurred at the bone–cement interface within 2 years after total elbow arthroplasty. The single patient with aseptic loosening in the notched group had a history of multiple surgeries due to an open fracture preceding the primary total elbow arthroplasty. Discussion Notching of the ulna component of the first-generation latitude total elbow prosthesis reduced the rate of aseptic loosening and improved implant survival. Level of evidence Level IV, retrospective comparative study.

Background: The management of severe radiocapitellar joint pathologies in young patients is challenging. Radial head arthroplasty (RHA) is a treatment option in the adult population, but most surgeons avoid implementing it in younger patients, and there are no published results for patients younger than 16 years. Methods: Our retrospective cohort describes 5 patients (4 male 1 female) who underwent cementless modular RHA at an average age of 14 years (range: 13 to 15). The preoperative diagnoses were post-traumatic radiocapitellar incongruity and arthrosis because of previous Salter-Harris type 3 or 4 fractures of the radial head in 3 cases; and axial instability of the forearm following failed radial head excision in 2 cases. Because of the complexity of the elbow pathology in these cases, all underwent concomitant procedures including: contracture release (5 cases), corrective ulnar osteotomy (2 cases), distal ulnar shortening osteotomy, excision of radioulnar synostosis, microfracture of the capitellum, and partial excision of the medial triceps (1 case each). Collected data included patient-reported outcomes, visual analog scale pain score at rest and during physical activity and radiographic assessment of arthritis and prosthesis loosening. Results: Average clinical follow-up was 8 years (range: 3 to 13). All 5 patients were pain-free at rest, and 3 reported moderate elbow pain (visual analog scale: 5 to 6) with physical activity. At an average radiographic follow-up of 3 years (range: 0.5 to 5), 3 patients showed mild progression of elbow arthrosis, but there were no signs of progressive capitellar erosion or implant loosening. Only 1 complication was noted—development of heterotopic ossification in 1 patient, which required open heterotopic ossification excision and contracture release 2 years following the RHA. None of the patients required prosthesis revision or removal. Conclusion: RHA was successful in improving pain and axial forearm stability in this very small series of adolescent patients. Concerns regarding long-term longevity and complications still exist. Considering the lack of other reliable treatment options, RHA may be indicated in this challenging patient population. Level of Evidence: Level IV: therapeutic study—case series.

Background: There is no consensus how to determine the varus laxity due to the LCL injury using the ultrasonography. There is a risk of lateral collateral ligament injury during or after arthroscopic extensor carpi radialis brevis release for tennis elbow. The equator of the radial head has been suggested as a landmark for the safe zone to not increase this risk; however, the safe zone from the intra-articular space has not been established. Hypothesis: Increased elbow varus laxity due to lateral collateral ligament–capsular complex (LCL-cc) injury could be assessed reliably via ultrasound. Study Design: Descriptive laboratory study. Methods: Eight cadaveric elbows were evaluated using a custom-made machine allowing passive elbow flexion under gravity varus stress. The radiocapitellar joint (RCJ) space was measured via ultrasound at 30° and 90° of flexion during 4 stages: intact elbow (stage 0), release of the anterior one-third of the LCL-cc (stage 1), release of the anterior two-thirds (stage 2), and release of the entire LCL-cc (stage 3). Two observers conducted the measurements separately, and the mean RCJ space in the 3 LCL-cc injury models (stages 1-3) at both flexion angles was compared with that of the intact elbow (stage 0). We also compared the measurements at 30° versus 90° of flexion. Results: At 30° of elbow flexion, the RCJ space increased 2 mm between stages 0 and 2 (95% confidence interval [CI], 1-3 mm; P < .01) and 4 mm between stages 0 and 3 (95% CI, 2-5 mm; P < .01). At 90° of elbow flexion, the RCJ space increased 1 mm between stages 0 and 2 (95% CI, 1-2 mm; P < .01) and 2 mm between stages 0 and 3 (95% CI, 2-3 mm; P < .01). Conclusion: Elbow varus laxity under gravity stress can be reliably assessed via ultrasound by measuring the RCJ space. Clinical Relevance: Because ultrasonographic measurement of the RCJ space can distinguish the increasing varus laxity seen with release of two-thirds or more of the LCL-cc, the anterior one-third of the LCL-cc, based on the diameter of the radial head, can be considered the safe zone in arthroscopic extensor carpi radialis brevis release for tennis elbow.

Background: Osteochondritis dissecans (OCD) of the capitellum is common in throwing athletes and is believed to result from repetitive overloading on the radiocapitellar (RC) joint, although the cause and mechanism remain unclear. The torsional forces (moments) generated by the triceps during elbow extension pull only on the ulna; therefore, the radial head moves passively across the capitellum and is effectively “dragged along” by the ulna. Any laxity in the proximal radioulnar joint could lead to asynchronous motion between the radius and ulna, resulting in the radial head lagging behind the coronoid and possibly malarticulating with the capitellum during such motion. Hypothesis: Radial head motion on the capitellum lags behind ulnohumeral joint motion during simulated throwing. Study Design: Controlled laboratory study. Methods: A total of 8 cadaveric elbows were tested under simulated throwing, including active extension of the elbow generated by pulling of the triceps under valgus stress, as well as during passive extension under valgus stress to serve as a reference. Ulnohumeral motion was tracked using a video camera. Radial head motion was tracked using an intra-articular, thin-film pressure sensor mounted on the capitellum, and the longitudinal movement of the center of force (COF) of the radial head was measured. Radial head motion was compared between passive and active motion for each 10° of elbow extension from 90° to 20°. Results: Elbow motion during simulated active extension reached an angular velocity of 366 deg/s. Radial head motion during simulated active extension significantly lagged compared with its motion during passive extension at every elbow extension angle examined between 70° and 20° ( P < .001). The maximal lag reached a mean of 4 mm (range, 2-7 mm). In other words, RC and ulnohumeral motion were asynchronous during simulated throwing. Conclusion: This study describes a novel phenomenon: motion of the radial head across the capitellum during rapid extension, such as in baseball pitching, lags behind that seen during passive elbow motion. According to a new proposed theory of OCD lesion development, this lag should result in RC incongruency and elevated shear forces on the capitellum due to edge loading. Clinical Relevance: We propose a new biomechanical explanation for OCD of the capitellum in baseball pitchers: radial head lag. Understanding this process is the first step in efforts to prevent this common injury.