Does Intraoperative Bone-Quality Assessment Correlate with Opportunistic CT-Based Hounsfield Unit Measurements?

Orthopaedic surgical intervention continues to revolve around intraoperative tactile and proprioceptive feedback, which ultimately impacts decision-making. The subjective intraoperative interpretation that “this is good bone” or “this is (insert adjective of choice) bone” certainly contributes to patient-specific treatment. The choice of both implant material and fixation construct relies on perceived bone quality. Furthermore, the total number of fixation constructs, the utility of locking screws, and augmentation with autograft or allograft, cement, and/or biologics are all avenues of current research to advance the success of fixation in bone with compromised quality. In 2016, JBJS published “Clinical and Radiographic Outcomes of the Simpliciti Canal-Sparing Shoulder Arthroplasty System: A Prospective Two-Year Multicenter Study” by Churchill et al., which described the “thumb test,” a subjective intraoperative assessment of bone quality1. Churchill et al. reported that “Bone that was easily compressed with minimal force was also considered not sufficient for implantation. If the physician subjectively determined that the bone had sufficient strength to support the press fit of the nucleus, the humerus was prepared with the standardized surgical technique outlined in the protocol…”1. Orthopaedic surgery is a “living organism,” constantly adapting and developing, and yet somehow remaining the same. Even with the advent of new technological imaging and platforms to assist with and guide surgical treatment strategies, there is no replacement for intraoperative tactile and proprioceptive feedback. What is fantastic about this manuscript by Lewis et al. is the link between subjective intraoperative experience and objective preoperative computed tomography (CT) in evaluating bone quality among various anatomic sites and surgeons. The strong methodological design included 7 surgeons who utilized a 10-point Likert scale to classify bone quality as “normal,” “osteopenic,” or “osteoporotic,” which was assessed in relation to recorded opportunistic CT-scan Hounsfield unit (HU) measurements. The results demonstrated that surgeons can reliably detect abnormal bone quality through intraoperative assessment across a wide breadth of anatomic sites, most commonly, the femur, ankle, acetabulum, and tibia. Receiver operating curve (ROC) analysis using surgeon bone-quality assessment to determine abnormal bone quality yielded an area under the curve (AUC) of 0.92 standard error (SE) = 0.027 and a high degree of sensitivity (84%) and specificity (97%). Furthermore, these findings remained consistent among subgroup analysis by anatomic site. At the very least, these results can provide orthopaedic surgeons with the confidence that actual intraoperative bone-quality assessment correlates with objective CT HU measurements. Prior studies by Nickel et al. and Martin et al. examined intraoperative bone quality among total knee and hip arthroplasty patients, respectively. Both studies observed a positive correlation between intraoperative assessment and objective bone-quality measures, and yet only 1 anatomic site was assessed in each2,3. The current manuscript truly expands on the current literature and provides generalizability to all subspecialties by involving not only multiple anatomic sites but also multiple surgeons. One can say that there are limitations to this study—or it is possible that the shortcomings of this study are just avenues for future research and exploration. To improve on cohort size, multicenter registry imaging investigations can be conducted. This will allow for the evaluation of additional anatomic sites as well as various patient populations with a spectrum of functional ability, medical comorbidities, and medication regimens. The ability to assess preoperative CT HU measurements among a subgroup of patients will not only provide more information for preoperative planning but also initiate further evaluation and management for osteopenia and osteoporosis. This initiative aligns with the Own the Bone movement in the U.S., a national system-based multidisciplinary approach to prevent fracture and post-fracture complications and recurrence4. It is critical that we remain confident in the application of technological innovation and how that correlates with our intraoperative expectations and experience. This will provide us with the greatest probability of maximizing patient-specific treatment and outcomes.