Non-invasive computer-assisted measurement of knee alignment

The quantification of knee alignment is a routine part of orthopaedic practice and is important for monitoring disease progression, planning interventional strategies, and follow-up of patients. Currently available technologies such as radiographic measurements have a number of drawbacks. The aim of this study was to validate a potentially improved technique for measuring knee alignment under different conditions. An image-free navigation system was adapted for non-invasive use through the development of external infrared tracker mountings. Stability was assessed by comparing the variance (F-test) of repeated mechanical femoro-tibial (MFT) angle measurements for a volunteer and a leg model. MFT angles were then measured supine, standing and with varus-valgus stress in asymptomatic volunteers who each underwent two separate registrations and repeated measurements for each condition. The mean difference and 95% limits of agreement were used to assess intra-registration and inter-registration repeatability. For multiple registrations the range of measurements for the external mountings was 1° larger than for the rigid model with statistically similar variance (p=0.34). Thirty volunteers were assessed (19 males, 11 females) with a mean age of 41 years (range: 20-65) and a mean BMI of 26 (range: 19-34). For intra-registration repeatability, consecutive coronal alignment readings agreed to almost ±1°, with up to ±0.5° loss of repeatability for coronal alignment measured before and after stress maneuvers, and a ±0.2° loss following stance trials. Sagittal alignment measurements were less repeatable overall by an approximate factor of two. Inter-registration agreement limits for coronal and sagittal supine MFT angles were ±1.6° and ±2.3°, respectively. Varus and valgus stress measurements agreed to within ±1.3° and ±1.1°, respectively. Agreement limits for standing MFT angles were ±2.9° (coronal) and ±5.0° (sagittal), which may have reflected a variation in stance between measurements. The system provided repeatable, real-time measurements of coronal and sagittal knee alignment under a number of dynamic, real-time conditions, offering a potential alternative to radiographs

A validation of the Nottingham Clavicle Score: a clavicle, acromioclavicular joint and sternoclavicular joint–specific patient-reported outcome measure

Background Patients with acromioclavicular joint (ACJ) and sternoclavicular joint (SCJ) injuries and with clavicle fractures are typically younger and more active than those with other shoulder pathologies. We developed the Nottingham Clavicle Score (NCS) specifically for this group of patients to improve sensitivity for assessing the outcomes of treatment of these conditions compared with the more commonly used Constant Score (CS) and Oxford Shoulder Score (OSS). Materials and methods This was a cohort study in which the preoperative and 6-month postoperative NCS evaluations of outcome in 90 patients were compared with the CS, OSS, Imatani Score (IS), and the EQ-5D scores. Reliability was assessed using the Cronbach α. Reproducibility of the NCS was assessed using the test/retest method. Effect sizes were calculated for each score to assess sensitivity to change. Validity was examined by correlations between the NCS and the CS, OSS, IS, and EQ-5D scores obtained preoperatively and postoperatively. Results Significant correlations were demonstrated preoperatively with the OSS (P = .025) and all subcategories of the EQ-5D (P < .05) and postoperatively with the OSS (P < .001), CS (P = .008), IS (P < .001), and all subcategories of EQ-5D (P < .02). The NCS had the largest effect size (1.92) of the compared scores. Internal consistency was excellent (Cronbach α = 0.87). Conclusion The NCS has been proven to be a valid, reliable and sensitive outcome measure that accurately measures the level of function and disability in the ACJ, SCJ and clavicle after traumatic injury and in degenerative disease

Acromioclavicular joint dislocation: a comparative biomechanical study of the palmaris-longus tendon graft reconstruction with other augmentative methods in cadaveric models

<p>Abstract</p> <p>Background</p> <p>Acromioclavicular injuries are common in sports medicine. Surgical intervention is generally advocated for chronic instability of Rockwood grade III and more severe injuries. Various methods of coracoclavicular ligament reconstruction and augmentation have been described. The objective of this study is to compare the biomechanical properties of a novel palmaris-longus tendon reconstruction with those of the native AC+CC ligaments, the modified Weaver-Dunn reconstruction, the ACJ capsuloligamentous complex repair, screw and clavicle hook plate augmentation.</p> <p>Hypothesis</p> <p>There is no difference, biomechanically, amongst the various reconstruction and augmentative methods.</p> <p>Study Design</p> <p>Controlled laboratory cadaveric study.</p> <p>Methods</p> <p>54 cadaveric native (acromioclavicular and coracoclavicular) ligaments were tested using the Instron machine. Superior loading was performed in the 6 groups: 1) in the intact states, 2) after modified Weaver-Dunn reconstruction (WD), 3) after modified Weaver-Dunn reconstruction with acromioclavicular joint capsuloligamentous repair (WD.ACJ), 4) after modified Weaver-Dunn reconstruction with clavicular hook plate augmentation (WD.CP) or 5) after modified Weaver-Dunn reconstruction with coracoclavicular screw augmentation (WD.BS) and 6) after modified Weaver-Dunn reconstruction with mersilene tape-palmaris-longus tendon graft reconstruction (WD. PLmt). Posterior-anterior (horizontal) loading was similarly performed in all groups, except groups 4 and 5. The respective failure loads, stiffnesses, displacements at failure and modes of failure were recorded. Data analysis was carried out using a one-way ANOVA, with Student's unpaired t-test for unpaired data (S-PLUS statistical package 2005).</p> <p>Results</p> <p>Native ligaments were the strongest and stiffest when compared to other modes of reconstruction and augmentation except coracoclavicular screw, in both posterior-anterior and superior directions (p < 0.005).</p> <p>WD.ACJ provided additional posterior-anterior (P = 0. 039) but not superior (p = 0.250) stability when compared to WD alone.</p> <p>WD+PLmt, in loads and stiffness at failure superiorly, was similar to WD+CP (p = 0.066). WD+PLmt, in loads and stiffness at failure postero-anteriorly, was similar to WD+ACJ (p = 0.084).</p> <p>Superiorly, WD+CP had similar strength as WD+BS (p = 0.057), but it was less stiff (p < 0.005).</p> <p>Conclusions and Clinical Relevance</p> <p>Modified Weaver-Dunn procedure must always be supplemented with acromioclavicular capsuloligamentous repair to increase posterior-anterior stability. Palmaris-Longus tendon graft provides both additional superior and posterior-anterior stability when used for acromioclavicular capsuloligamentous reconstruction. It is a good alternative to clavicle hook plate in acromioclavicular dislocation.</p