BACKGROUND: Recurrent glenohumeral anterior instability (RGAI) frequently induces combined glenoid and Hill-Sachs bone lesions and is a risk factor for soft tissue repair failure. This cohort study describes a simple preoperative quantification method for bone loss, the Clock method, the first that combines glenoid and humeral lesions. METHODS: Computed tomography scans of 34 shoulders with RGAI were twice reviewed by three independent observers, who measured bone lesions using the new Clock method and existing validated methods. Intra- and inter-observer reliability of the Clock method was evaluated (intraclass correlation coefficient). Pearson correlation was used to correlate Clock method with existing methods, and with function (Western Ontario Shoulder Instability, Quick-Disabilities of the Arm, Shoulder and Hand). RESULTS: Thirty-two patients met the inclusion criteria: three females and 29 males, mean age 28 years. The intra- and inter-observer reliability was excellent, with intraclass correlation coefficient ranging from 0.817 to 0.938 for the novel Clock method. Humeral Clock and Glenoid Clock strongly correlated with Humeral Ratio (r = 0.882, p < 0.001) and Glenoid Surface Area and Glenoid Ratio (r = 0.793 and 0.717, p < 0.001), respectively. The classic threshold of 25% of the glenoid diameter with the Glenoid Ratio method corresponds to 4 hours with the Glenoid Clock method. CONCLUSIONS: The Clock method is quick and reliable, with more studies being needed to investigate whether it is correlated with surgical outcomes.
BACKGROUND: Recurrent glenohumeral anterior instability (RGAI) frequently induces combined glenoid and Hill-Sachs bone lesions and is a risk factor for soft tissue repair failure. This cohort study describes a simple preoperative quantification method for bone loss, the Clock method, the first that combines glenoid and humeral lesions. METHODS: Computed tomography scans of 34 shoulders with RGAI were twice reviewed by three independent observers, who measured bone lesions using the new Clock method and existing validated methods. Intra- and inter-observer reliability of the Clock method was evaluated (intraclass correlation coefficient). Pearson correlation was used to correlate Clock method with existing methods, and with function (Western Ontario Shoulder Instability, Quick-Disabilities of the Arm, Shoulder and Hand). RESULTS: Thirty-two patients met the inclusion criteria: three females and 29 males, mean age 28 years. The intra- and inter-observer reliability was excellent, with intraclass correlation coefficient ranging from 0.817 to 0.938 for the novel Clock method. Humeral Clock and Glenoid Clock strongly correlated with Humeral Ratio (r = 0.882, p < 0.001) and Glenoid Surface Area and Glenoid Ratio (r = 0.793 and 0.717, p < 0.001), respectively. The classic threshold of 25% of the glenoid diameter with the Glenoid Ratio method corresponds to 4 hours with the Glenoid Clock method. CONCLUSIONS: The Clock method is quick and reliable, with more studies being needed to investigate whether it is correlated with surgical outcomes.
Authors: Robert A Arciero; Anthony Parrino; Andrew S Bernhardson; Vilmaris Diaz-Doran; Elifho Obopilwe; Mark P Cote; Petr Golijanin; Augustus D Mazzocca; Matthew T Provencher Journal: Am J Sports Med Date: 2015-03-20 Impact factor: 6.202