Atrophy patterns in isolated subscapularis lesions.

BACKGROUND: While supraspinatus atrophy can be described according to the system of Zanetti or Thomazeau there is still a lack of characterization of isolated subscapularis muscle atrophy. The aim of this study was to describe patterns of muscle atrophy following repair of isolated subscapularis (SSC) tendon. METHODS: Forty-nine control shoulder MRI scans, without rotator cuff pathology, atrophy or fatty infiltration, were prospectively evaluated and subscapularis diameters as well as cross sectional areas (complete and upper half) were assessed in a standardized oblique sagittal plane. Calculation of the ratio between the upper half of the cross sectional area (CSA) and the total CSA was performed. Eleven MRI scans of patients with subscapularis atrophy following isolated subscapularis tendon tears were analysed and cross sectional area ratio (upper half /total) determined. To guarantee reliable measurement of the CSA and its ratio, bony landmarks were also defined. All parameters were statistically compared for inter-rater reliability, reproducibility and capacity to quantify subscapularis atrophy. RESULTS: The mean age in the control group was 49.7 years (± 15.0). The mean cross sectional area (CSA) was 2367.0 mm2 (± 741.4) for the complete subscapularis muscle and 1048.2 mm2 (± 313.3) for the upper half, giving a mean ratio of 0.446 (± 0.046). In the subscapularis repair group the mean age was 56.7 years (± 9.3). With a mean cross sectional area of 1554.7 mm2 (± 419.9) for the complete and of 422.9 mm2 (± 173.6) for the upper half of the subscapularis muscle, giving a mean CSA ratio of 0.269 (± 0.065) which was seen to be significantly lower than that of the control group (p < 0.05). CONCLUSION: Analysis of typical atrophy patterns of the subscapularis muscle demonstrates that the CSA ratio represents a reliable and reproducible assessment tool in quantifying subscapularis atrophy. We propose the classification of subscapularis atrophy as Stage I (mild atrophy) in case of reduction of the cross sectional area ratio < 0.4, Stage II (moderate atrophy) in case of < 0.35 and Stage III (severe atrophy) if < 0.3.

The V-shaped subscapularis tenotomy for anatomic total shoulder arthroplasty.

PURPOSE: Management of the subscapularis tendon during anatomic total shoulder arthroplasty (TSA) remains controversial. In our unit, subscapularis tenotomy is the preferred technique; however, the potential for tendon gapping and failure is recognised. The purpose of this study is to describe and provide early clinical results of a novel, laterally based V-shaped tenotomy (VT) technique hypothesised to provide greater initial repair strength and resistance to gapping than a transverse tenotomy (TT), with both clinically and radiologically satisfactory post-operative tendon healing and function. METHODS: A retrospective study of patients who underwent primary TSA with VT over a three year period was performed using shoulder and subscapularis-specific outcome scores, radiographs, and ultrasound. A separate cohort of patients who underwent TSA using a subscapularis sparing approach was also reviewed to provide comparative clinical outcomes of a group with TSA and an un-violated subscapularis. RESULTS: Eighteen patients were reviewed at mean 30.4 months (± 11.7). Constant (78.2 ± 12.3), UCLA (8.4 ± 1.5), pain VAS (2.3 ± 2.8), and strength in internal rotation were no different from the comparison group. Likewise, neither were the clinical outcomes of range-of-motion, belly-press, lift-off, and shirt-tuck tests. One patient (5.5%) was found to have a failed subscapularis repair on ultrasound. CONCLUSION: VT during TSA appears to provide healing rates at least equal to those reported for TT, and not dissimilar from those of lesser tuberosity osteotomy. Clinical outcomes are comparable to reported results in the literature for alternative techniques, and not different from those observed here in a comparison cohort with TSA performed without violating the subscapularis tendon. VT therefore potentially offers a more effective and secure tendon repair than a traditional TT, with at least comparable clinical outcomes.

Locking nail versus locking plate for proximal humeral fracture fixation in an elderly population: a prospective randomised controlled trial.

BACKGROUND: Proximal humeral fractures (PHFs) are the third most common fracture in older patients. The purpose of the study was to prospectively evaluate the outcomes of PHF fixation with a locking blade nail (LBN) or locking plate (PHILOS) osteosynthesis in a homogeneous elderly patient population. METHODS: Inclusion criteria were an age > 60 years and the capacity to give informed consent. Patients with isolated tuberosity fractures, previous trauma or surgery, advanced osteoarthritis, fracture dislocation, pathological fractures, open fractures, neurological disorders, full-thickness rotator cuff tears, fracture line at the nail entry point or severely reduced bone quality intra-operatively were excluded. Eighty one patients with PHFs were randomised to treatment using LBN or PHILOS. Outcome measures comprised Constant score, age and gender adjusted Constant score, DASH score, VAS for pain, subjective overall condition of the shoulder (1-6) and active shoulder range-of-motion in flexion and abduction. Plain radiographs were obtained in two planes. All data were collected by an independent observer at 3, 6 and 12 months postoperatively. RESULTS: Thirteen patients were excluded intra-operatively due to rotator cuff tears, fracture morphology or poor bone-quality. Of the remaining 68 patients, 27 in the LBN and 28 in the PHILOS group completed the full follow-up. Mean age at surgery was 75.6 years and the majority of PHFs were three-part fractures (49 patients). Baseline demographics between groups were comparable. All outcome measures improved between assessments (p < 0.001). The LBN group showed improved DASH scores as compared to PHILOS at 12 months (p = 0.042) with fewer incidences of secondary loss of reduction and screw cut-out (p = 0.039). A total of 29 complications (in 23 patients) were recorded, 13 complications (in 12 patients) in the LBN group and 16 complications (in 11 patients) in the PHILOS group (p = 0.941). No significant inter-group difference was observed for any other outcome measures, nor was fracture morphology seen to be associated with clinical outcome or complication rate. CONCLUSIONS: At short-term follow-up, LBN osteosynthesis yielded similar outcomes and complication rates to PHILOS plate fracture fixation in an elderly patient population, though with a significantly lower rate of secondary loss of reduction and screw cut-out. REGISTRATION TRIAL: No. DRKS00015245 at Deutsches Register Klinischer Studien, registered: 22.08.2018, retrospectively registered.

Does the Arthroscopic Latarjet Procedure Effectively Correct "Off-Track" Hill-Sachs Lesions?

BACKGROUND: The glenoid track concept describes the dynamic interaction of bipolar bone loss in anterior glenohumeral instability. Initial studies have successfully demonstrated this concept's application in clinical populations. In clinical practice, the Latarjet procedure is commonly the preferred treatment in addressing "off-track" Hill-Sachs lesions. The effectiveness of this procedure in restoring such lesions to an "on-track" state, however, has not yet been evaluated or described in the literature. HYPOTHESIS: The Latarjet procedure would transform "off-track" Hill-Sachs lesions to "on-track" lesions. Lesions would remain "on-track" during follow-up, despite glenoid remodeling. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients with "off-track" Hill-Sachs lesions treated with the arthroscopic Latarjet procedure between March 2013 and May 2014 were included. Glenoid track and coracoid graft contact surface area measurements using 3-dimensional computed tomography (3D-CT) were performed preoperatively and at 6-week, 6-month, and at least 12-month (final) follow-up. The mean final follow-up was 23 months. The glenoid diameter, as a percentage of the native glenoid, was also calculated from this imaging. RESULTS: Twenty-six patients met the inclusion criteria. 3D-CT scans were available for all patients preoperatively and postoperatively, with 21 patients (81%) undergoing 6-month follow-up CT and 19 patients (73%) undergoing final follow-up CT. Hill-Sachs lesions remained "on-track" at all follow-up time points. The mean glenoid diameter changed significantly from 84.6% preoperatively to 122.8% at 6 weeks ( P < .001) and from 120.5% at 6 months to 113.9% at final follow-up ( P = .005). This was also reflected in significant remodeling seen in the coracoid graft articular contact area (6 weeks to 6 months, P = .024; 6 months to final follow-up, P = .002). This persisting glenoid arc enlargement at final follow-up avoided "off-track" Hill-Sachs lesions in 6 of 19 patients (32%), which would otherwise have occurred had the coracoid graft remodeled to native glenoid dimensions. CONCLUSION: The Latarjet procedure provides an effective treatment for "off-track" engaging Hill-Sachs lesions, despite an evident glenoid remodeling process. At a mean of 23 months postoperatively, a mean persisting enlargement of the glenoid arc of 14% beyond native dimensions remained, avoiding a recurrent "off-track" lesion in 32% of patients, which would otherwise have occurred with complete remodeling.

What Are the Biomechanical Properties of the Taylor Spatial Frame™?

BACKGROUND: The Taylor Spatial Frame™ (TSF) is a versatile variant of the traditional Ilizarov circular fixator. Although in widespread use, little comparative data exist to quantify the biomechanical effect of substituting the tried-and-tested Ilizarov construct for the TSF hexapod system. QUESTIONS/PURPOSES: This study was designed to investigate the mechanical properties of the TSF system under physiologic loads, with and without the addition of a simulated bone model, with comparison to the standard Ilizarov frame. METHODS: The mechanical behaviors of three identical four-ring TSF and Ilizarov constructs were tested under levels of axial compression, bending, and rotational torque to simulate loading during normal gait. An acrylic-pipe fracture model subsequently was mounted, using fine wires and 5 mm half pins, and the testing was repeated. Load-deformation curves, and so rigidity, for each construct were calculated, with statistical comparisons performed using paired t-tests. RESULTS: Under axial loading, the TSF was found to be less rigid than the Ilizarov frame (645 ± 57 N/mm versus 1269 ± 256 N/mm; mean difference, 623 N/mm; 95% CI, 438.3-808.5 N/mm; p < 0.001), but more rigid under bending and torsional loads (bending: 42 ± 9 Nm/degree versus 78 ± 13 Nm/degree; mean difference, 37 Nm/degree; 95% CI, 25.0-47.9 Nm/degree; p < 0.001; torsion: 16 ± 2 Nm/degree versus 5 ± 0.35 Nm/degree; mean difference, 11 Nm/degree; 95% CI, 9.5-12.2 Nm/degree; p < 0.001). On mounting the bone models, these relationships broadly remained in the half-pin and fine-wire groups, however the half-pin constructs were universally more rigid than those using fine wires. This effect resulted in the TSF, using half pins, showing no difference in axial rigidity to the fine-wire Ilizarov (107 ± 3 N/mm versus 107 ± 4 N/mm; mean difference, 0.05 N/mm; 95% CI, -6.99 to 7.1 N/mm; p > 0.999), while retaining greater bending and torsional rigidity. Throughout testing, a small amount of laxity was observed in the TSF construct on either side of neutral loading, amounting to 0.72 mm (±0.37 mm) for a change in loading between -10 N and 10 N axial load, and which persisted with the addition of the synthetic fracture model. CONCLUSIONS: This study broadly shows the TSF construct to generate lower axial rigidity, but greater bending and torsional rigidity, when compared with the Ilizarov frame, under physiologic loads. The anecdotally described laxity in the TSF hexapod strut system was shown in vitro, but only at low levels of loading around neutral. It also was shown that the increased stiffness generated by use of half pins produced a TSF construct replicating the axial rigidity of a fine-wire Ilizarov frame, for which much evidence of good clinical and radiologic outcomes exist, while providing greater rigidity and so improved resistance to potentially detrimental bending and rotational shear loads. CLINICAL RELEVANCE: If replicated in the clinical setting, these findings suggest that when using the TSF, care should be taken to minimize the observed laxity around neutral with appropriate preloading of the construct, but that its use may produce constructs better able to resist bending and torsional loading, although with lower axial rigidity. Use of half pins in a TSF construct however may replicate the axial mechanical behavior of an Ilizarov construct, which is thought to be conducive to bone healing.

An Arthroscopic Humeral Medializing Repair of the Supraspinatus.

Posterosuperior repair of the rotator cuff is one of the most frequently performed surgical procedures in the shoulder. Its aim is to fix the tendon back to the bone to restore anatomy, improve shoulder function, and prevent progression of cuff tear arthropathy and attendant muscle degeneration. Despite technical advances in this procedure, in some cases, the tendon cannot be fixed back to the footprint without excessive tension on the repair. In young patients or in patients with low-grade muscle atrophy and fatty degeneration (Goutallier grade 1 or 2), it is mandatory to attempt fixation of the tendon to restore functional anatomy and prevent further muscle degeneration. In such cases, an arthroscopic medialized reinsertion of the supraspinatus may be considered. We describe an arthroscopic humeral medializing repair of the supraspinatus tendon that allows for a tension-free repair of the supraspinatus using common portals and instruments. The goal of this technique is to obtain tendon healing, restore functional anatomy, and prevent atrophy and fatty degeneration of the muscles of the rotator cuff.

Arthroscopic Repair of Subscapularis Tendon Tears.

The subscapularis is the largest and strongest muscle of the rotator cuff, and it plays an essential role in global shoulder function. Beyond its primary function as an internal rotator, the subscapularis also acts to pull the humeral head posteriorly on the glenoid and is an important dynamic and static anterior stabilizer of the glenohumeral joint. In comparison with tears of the tendons of the rest of the rotator cuff, isolated tears of the subscapularis have a tendency for both early retraction and fatty infiltration. Consequently, full-thickness tears of the subscapularis tendon generally require surgical management. Arthroscopic suture-anchor repair allows anatomic reconstruction of the anterior aspect of the rotator cuff, with all of the benefits of arthroscopic surgery. The principal steps of this procedure include (1) verifying the subscapularis tear and identifying any concomitant lesions during diagnostic arthroscopy, (2) exposing the subscapularis tendon, (3) releasing tendon adhesions and so enabling anatomic reduction, (4) placing suture anchors at the anatomic subscapularis footprint on the lesser tuberosity and anatomically repairing the subscapularis tendon to its anatomic insertion, and (5) performing biceps tenodesis or tenotomy, if indicated. Postoperatively, patients with an isolated subscapularis tear are managed with immobilization in a sling for 6 weeks, while those with combined anterosuperior rotator cuff tears are managed with an abduction pillow. Arthroscopic subscapularis reconstruction provides a good structural repair, substantially restores shoulder mobility and strength, reduces pain, and results in high levels of patient satisfaction and return of shoulder function as measured by functional outcome scores.

What Are the Biomechanical Effects of Half-pin and Fine-wire Configurations on Fracture Site Movement in Circular Frames?

BACKGROUND: Fine-wire circular frame (Ilizarov) fixators are hypothesized to generate favorable biomechanical conditions for fracture healing, allowing axial micromotion while limiting interfragmentary shear. Use of half-pins increases fixation options and may improve patient comfort by reducing muscle irritation, but they are thought to induce interfragmentary shear, converting beam-to-cantilever loading. Little evidence exists regarding the magnitude and type of strain in such constructs during weightbearing. QUESTIONS/PURPOSES: This biomechanical study was designed to investigate the levels of interfragmentary strain occurring during physiologic loading of an Ilizarov frame and the effect on this of substituting half-pins for fine-wires. METHODS: The "control" construct was comprised of a four-ring all fine-wire construct with plain wires at 90°-crossing angles in an entirely unstable acrylic pipe synthetic fracture model. Various configurations, substituting half-pins for wires, were tested under levels of axial compression, cantilever bending, and rotational torque simulating loading during gait. In total three frames were tested for each of five constructs, from all fine-wire to all half-pin. RESULTS: Substitution of half-pins for wires was associated with increased overall construct rigidity and reduced planar interfragmentary motion, most markedly between all-wire and all-pin frames (axial: 5.9 mm ± 0.7 vs 4.2 mm ± 0.1, mean difference, 1.7 mm, 95% CI, 0.8-2.6 mm, p < 0.001; torsional: 1.4% ± 0.1 vs 1.1% ± 0.0 rotational shear, mean difference, 0.3%, 95% CI, 0.1%-0.5%, p = 0.011; bending: 7.5° ± 0.1 vs 3.4° ± 0.1, mean difference, -4.1°, 95% CI, -4.4° to -3.8°, p < 0.001). Although greater transverse shear strain was observed during axial loading (0.4% ± 0.2 vs 1.9% ± 0.1, mean difference, 1.4%, 95% CI, 1.0%-1.9%, p < 0.001), this increase is unlikely to be of clinical relevance given the current body of evidence showing bone healing under shear strains of up to 25%. The greatest transverse shear was observed under bending loads in all fine-wire frames, approaching 30% (29% ± 1.9). This was reduced to 8% (±0.2) by incorporation of sagittal plane half-pins and 7% (±0.2) in all half-pin frames (mean difference, -13.2% and -14.0%, 95% CI, -16.6% to 9.7% and -17.5% to -10.6%, both p < 0.001). CONCLUSIONS: Appropriate use of half-pins may reduce levels of shear strain on physiologic loading of circular frames without otherwise altering the fracture site mechanical environment at levels likely to be clinically important. Given the limitations of a biomechanical study using a symmetric and uniform synthetic bone model, further clinical studies are needed to confirm these conclusions in vivo. CLINICAL RELEVANCE: The findings of this study add to the overall understanding of the mechanics of circular frame fixation and, if replicated in the clinical setting, may be applied to the preoperative planning of frame treatment, particularly in unstable fractures or bone transport where control of shear strain is a priority.

Functional outcomes after tibial shaft fractures treated using the Taylor spatial frame.

OBJECTIVES: To analyze functional and radiologic outcomes of tibial shaft fractures treated with the Taylor spatial frame (TSF). DESIGN: Prospective follow-up study of radiologic and functional outcomes. SETTING: University teaching hospital. PATIENTS: From January 2006 to December 2012, prospective data were collected for 56 consecutive patients completing treatment of a tibial shaft fracture with the TSF. INTERVENTION: Treatment of tibial shaft fractures, including those with simple extension into the knee or ankle joints, using the TSF. MAIN OUTCOME MEASUREMENTS: Residual deformity on x-ray and functional outcomes using the EQ-5D health status questionnaire, Iowa Knee and Ankle Evaluation Rating System scores, and Olerud and Molander Ankle score were recorded 1 year after frame removal. RESULTS: Average residual deformity was 1.8 degrees in the coronal and 1.6 degrees in the sagittal planes. EQ-5D outcomes showed patients returning to a health status no different from scores for the UK population as a whole. Iowa Knee scores demonstrated "good" or "excellent" outcomes in 87.3% of our cohort (mean, 90). Ankle Evaluation Rating System scores and Olerud and Molander Ankle scores showed "good" or "excellent" outcomes in 76.8% and 89.3% of our cohort, respectively (mean, 84.1 and 84). CONCLUSIONS: Use of the TSF for treatment of tibial fractures, with support from a dedicated limb reconstruction rehabilitation team, has a number of technical advantages while producing good functional and surgical outcomes, with patients recovering to a pre-injury health status. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Nonparametric estimation and testing of fixed effects panel data models.

In this paper we consider the problem of estimating nonparametric panel data models with fixed effects. We introduce an iterative nonparametric kernel estimator. We also extend the estimation method to the case of a semiparametric partially linear fixed effects model. To determine whether a parametric, semiparametric or nonparametric model is appropriate, we propose test statistics to test between the three alternatives in practice. We further propose a test statistic for testing the null hypothesis of random effects against fixed effects in a nonparametric panel data regression model. Simulations are used to examine the finite sample performance of the proposed estimators and the test statistics.