Femoral head allograft for glenoid bone loss in primary reverse shoulder arthroplasty: functional and radiologic outcomes.

BACKGROUND: Several techniques have been adopted during primary reverse shoulder arthroplasty (RSA) to manage glenoid bone defect. Among bone grafts, humeral head autograft is currently the mainstream option. However, autologous humeral heads may be unavailable or inadequate, and allografts may be a viable alternative. The aim of the present study was to evaluate the functional and radiologic outcomes of femoral head allografts for glenoid bone defects in primary RSA. METHODS: We conducted a retrospective study with prospective data collection enrolling 20 consecutive patients who underwent RSA with femoral head allografts for glenoid bone defects. Indications for surgery were eccentric cuff tear arthropathy in 10 cases (50%), concentric osteoarthritis in 9 cases (45%), and fracture sequelae in 1 case (5%). Each patient was evaluated preoperatively and at follow-up by radiologic and computed tomography (CT) and by assessing the range of motion (ROM) and the Constant-Murley score (CMS). A CT-based software, a patient-specific 3D model of the scapula, and patient-specific instrumentation were used to shape the graft and to assess the position of K-wire for the central peg. Postoperatively, CT scans were used to identify graft incorporation and resorption. RESULTS: After a median follow-up of 26.5 months (24-38), ROM and CMS showed a statistically significant improvement (all P = .001). The median measures of the graft were as follows: 28 mm (28-29) for diameter, 22° (10°-31°) for angle, 4 mm (2-8 mm) for minimum thickness, and 15 mm (11-21 mm) for maximum thickness. Before the surgery, the median glenoid version was 21.8° (16.5°-33.5°) for the retroverted glenoids and -13.5° (-23° to -12°) for the anteverted glenoids. At the follow-up, the median postoperative baseplate retroversion was 5.7° (2.2°-1.5°) (P = .001), and this value was close to the 4° retroversion planned on the preoperative CT-based software. Postoperative major complications were noted in 4 patients: 2 dislocations, 1 baseplate failure following a high-energy trauma, and 1 septic baseplate failure. Partial graft resorption without glenoid component failure was observed in 3 cases that did not require revision surgery. CONCLUSION: The femoral head allograft for glenoid bone loss in primary RSA restores shoulder function, with CMS values comparable to those of sex- and age-matched healthy individuals. A high rate of incorporation of the graft and satisfactory correction of the glenoid version can be expected after surgery. The management of glenoid bone defects remains a challenging procedure, and a 15% risk of major complication must be considered.

Arthroscopic repair for isolated subscapularis tear: successful functional outcomes and high tendon healing rate can be expected nine years after surgery.

BACKGROUND: Literature describing outcomes and integrity after isolated subscapularis (SSC) tendon repair is emerging but remains limited to a few small case series with short-term follow-up. The aim of this study was to evaluate the long-term clinical outcomes and repair integrity in patients who underwent arthroscopic repair of isolated SSC tears. METHODS: A retrospective study was conducted with the following inclusion criteria: (1) primary and elective shoulder arthroscopy for isolated SSC repair, (2) type III (a full-thickness tear in the upper two-thirds of the tendon) or IV (a complete tear without tendon retraction) SSC tear according to the Lafosse classification, and (3) a minimum 24-month follow-up. Preoperatively, the range of motion (ROM) and the Constant-Murley score (CMS) and at follow-up, the ROM, the University of California-Los Angeles (UCLA) Shoulder Rating Scale, the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire, and the CMS were evaluated; an ultrasonographic assessment of tendon healing was performed according to the Sugaya classification. RESULTS: The final sample consisted of 45 patients with an average age of 55 ± 9 years. After a mean follow-up time of 107 ± 54 months, the mean UCLA and DASH scores were 8.7 ± 1.3 and 42.2 ± 6.4, respectively. ROM and CMS showed statistically significant improvements (all P < .001). Before surgery, the mean CMS was 49% that of sex- and age-matched healthy individuals, and all patients showed a CMS lower than the normative data. At the final follow-up visit, the mean CMS was 94.2% that of sex- and age-matched healthy individuals, and no patients showed CMS of 30 or less. The mean increase in the CMS was 41.4 ± 9.8 points (range, 23-60 points). The ultrasonographic assessment showed SSC tendon healing in 39 (86.7%) cases; tendon retear was recorded in 5 (13.3%) cases. All scores directly correlated with the healing of the tendon. A higher postoperative DASH score was associated with male sex (P = .039, ß = 5.538) and a longer follow-up period (P = .044, ß = 0.001). The postoperative CMS (P < .001) and UCLA scores (P = .001) were significantly higher in patients younger than 60 years of age at surgery than in older individuals. CONCLUSION: Arthroscopic repair of isolated SSC tears achieves excellent clinical and functional results at a mean of 9 years postoperatively, with a satisfactory healing rate. Better functional outcomes correlate with SSC tendon integrity and were observed in male patients and in those younger than 60 years at surgery.

Common, low-frequency, rare, and ultra-rare coding variants contribute to COVID-19 severity.

The combined impact of common and rare exonic variants in COVID-19 host genetics is currently insufficiently understood. Here, common and rare variants from whole-exome sequencing data of about 4000 SARS-CoV-2-positive individuals were used to define an interpretable machine-learning model for predicting COVID-19 severity. First, variants were converted into separate sets of Boolean features, depending on the absence or the presence of variants in each gene. An ensemble of LASSO logistic regression models was used to identify the most informative Boolean features with respect to the genetic bases of severity. The Boolean features selected by these logistic models were combined into an Integrated PolyGenic Score that offers a synthetic and interpretable index for describing the contribution of host genetics in COVID-19 severity, as demonstrated through testing in several independent cohorts. Selected features belong to ultra-rare, rare, low-frequency, and common variants, including those in linkage disequilibrium with known GWAS loci. Noteworthily, around one quarter of the selected genes are sex-specific. Pathway analysis of the selected genes associated with COVID-19 severity reflected the multi-organ nature of the disease. The proposed model might provide useful information for developing diagnostics and therapeutics, while also being able to guide bedside disease management.

Subacromial Balloon Spacer for Massive, Irreparable Rotator Cuff Tears Is Associated With Improved Shoulder Function and High Patient Satisfaction.

PURPOSE: To investigate associations between clinical and demographic parameters and Constant-Murley (CM) scores after subacromial balloon placement for massive, irreparable rotator cuff tears and to evaluate implant survival, shoulder function, and patient satisfaction. METHODS: We prospectively analyzed patients with rotator cuff tears deemed irreparable on preoperative magnetic resonance imaging for whom nonoperative therapy was unsuccessful and who underwent balloon placement from 2014 to 2017 with minimum 1-year follow-up. Shoulder function was assessed using the CM score and the 12-Item Short Form Health Survey. RESULTS: The study included 51 patients (22 women and 29 men) with a mean age at surgery of 63 years (range, 50-78 years). The mean follow-up period was 36 months (range, 24-56 months). The postoperative acromiohumeral interval and total preoperative CM score predicted the postoperative CM score at final follow-up. The implant survival rates were 92% at 6 and 12 months, 90% at 2 years, and 87% at 3 and 4 years. Five patients underwent reverse total shoulder arthroplasty, and 1 underwent latissimus dorsi tendon transfer. Postoperatively, mean CM scores (± standard deviation) improved for range of motion (from 11 ± 5.4 to 34 ± 6.8) and strength (from 13 ± 5.4 to 28 ± 12) (P < .01 for both). The total CM score improved from 27 ± 7.4 preoperatively to 77 ± 15 postoperatively (P < .01). The physical and mental component summary scores on the 12-Item Short Form Health Survey improved from 27 ± 5.0 to 51 ± 6.5 (P = .02) and from 44 ± 15 to 56 ± 8.0, respectively (P < .01). Thirty-eight patients reported excellent satisfaction, 8 were satisfied, and 5 were dissatisfied. Of the patients, 50 (98%) exceeded the minimal clinically important difference (≥10.4) and patient acceptable symptom state (≥44). CONCLUSIONS: At mean 3-year follow-up, subacromial balloon spacer placement for massive, irreparable rotator cuff tears was associated with a significant improvement in shoulder function, limited need for revision surgery, and high patient satisfaction. A greater postoperative acromiohumeral interval and lower preoperative CM score predicted a lower postoperative CM score at final follow-up. LEVEL OF EVIDENCE: Level IV, retrospective cohort study and treatment study.

Functional outcomes and repair integrity after arthroscopic repair of partial articular supraspinatus tendon avulsion.

INTRODUCTION: Partial-thickness rotator cuff tears are a common cause of shoulder pain and disability. Arthroscopic repair is an effective treatment for partial articular supraspinatus tendon avulsion (PASTA) lesions, and transtendon repair and completion of the tear and repair are the surgical techniques commonly used to treat such lesions. Our aim was to retrospectively evaluate the minimum 24-month clinical and radiological results of PASTA. MATERIALS AND METHODS: Patients suffering from PASTA lesion who underwent arthroscopic repair with a minimum 24-month follow-up were included in this study. The Constant and Murley score (CMS) was used to assess the patients' functionality pre- and postoperatively. The postoperative patient assessment included the simple shoulder test (SST). Postoperative tendon integrity was evaluated by ultrasound examination. RESULTS: 151 patients (153 shoulders) were retrospectively evaluated 73.9 (24-142) months after a completion-repair (94 cases) or transtendon repair (59 cases) of a PASTA lesion. The CMS significantly improved from 47.7 (22-63) preoperatively to 84.2 (62-100) postoperatively (p < 0.001). The mean postoperative SST score was 10.1 (5-12), and 95% of patients were satisfied with the surgery. No significant differences were noted between the two techniques in terms of postoperative CMS, SST score and satisfaction. Seventy-four and 43 cases treated with completion and repair and transtendon repair, respectively, performed ultrasound examination 66.1 (24-142) months after surgery. The overall retear rate was 13.7%, supraspinatus retears were observed in ten shoulder subjected to completion and repair (13.5%) and six shoulders subjected to transtendon repair (13.9%), and no significant differences were noted between the two techniques as for CMS (p = 0.896), SST (p = 0.973), satisfaction (p = 0.621) and retear (p = 0.999). Males and younger patients had a higher postoperative CMS (p values < 0.001), and SST score (p < 0.001 and p = 0.038, respectively). CONCLUSIONS: Arthroscopic repair of PASTA lesion achieves high rates of repair integrity regardless of repair type and high levels of functional recovery and patient satisfaction 6 years after surgery.

Tenodesis is not superior to tenotomy in the treatment of the long head of biceps tendon lesions.

PURPOSE: To compare the effectiveness of tenodesis and tenotomy in the treatment of long head of the biceps tendon (LHBT) lesions. The null hypothesis was that there is no difference in functional scores between the tenotomy and tenodesis groups. METHODS: A total of 69 patients with a combined supraspinatus tear and LHBT lesion aged over 40 years entered this prospective comparative study and were randomly assigned to the arthroscopic LHB tenotomy or tenodesis group. Fifty-five patients (31 in the tenotomy group and 24 in the tenodesis group) were available for the 6- and 24-month post-operative evaluations. RESULTS: There were no statistically significant differences in post-operative Constant and Murley score, quality of life, pain, and strengths between groups. Higher rates of Popeye's sign were noted 6 and 24 months post-operatively in the tenotomy group compared to tenodesis. CONCLUSIONS: Although tenotomy is affected by a higher incidence of cosmetic deformity, there is no superiority of arthroscopic tenodesis over tenotomy in the treatment of LHBT lesion as a concomitant procedure to an arthroscopic repair of the supraspinatus tendon in terms of functional outcomes, quality of life, pain, and strength measured 6 and 24 months post-operatively. LEVEL OF EVIDENCE: I.

LQG Online Learning.

Optimal control theory and machine learning techniques are combined to formulate and solve in closed form an optimal control formulation of online learning from supervised examples with regularization of the updates. The connections with the classical linear quadratic gaussian (LQG) optimal control problem, of which the proposed learning paradigm is a nontrivial variation as it involves random matrices, are investigated. The obtained optimal solutions are compared with the Kalman filter estimate of the parameter vector to be learned. It is shown that the proposed algorithm is less sensitive to outliers with respect to the Kalman estimate (thanks to the presence of the regularization term), thus providing smoother estimates with respect to time. The basic formulation of the proposed online learning framework refers to a discrete-time setting with a finite learning horizon and a linear model. Various extensions are investigated, including the infinite learning horizon and, via the so-called kernel trick, the case of nonlinear models.

Quality of Life and Functional Results of Arthroscopic Partial Repair of Irreparable Rotator Cuff Tears.

PURPOSE: To evaluate the minimum 2-year results and possible outcomes of arthroscopic partial repair in different patterns of irreparable rotator cuff tears (RCTs). METHODS: Patients suffering from an irreparable supraspinatus and a reparable infraspinatus tendons who underwent arthroscopic partial repair with a minimum 24-month follow-up were included in this study. The Constant and Murley score (CMS) was used to assess patients' functionality pre- and postoperatively. Postoperative patient assessment included the Simple Shoulder Test (SST) and the Short Form Health Survey questionnaire (SF-36). A postoperative range of motion, CMS, and strength were compared with the contralateral side. Postoperative SF-36 was compared with age- and sex-matched norms. RESULTS: Ninety patients (95 shoulders) were reviewed after a mean follow-up of 7 (range 2-12) years. The subscapularis tendon was intact in 80 shoulders and torn but completely reparable in the remaining 15 shoulders. The CMS improved from 39.1 ± 8.4 (10-61) to 76.3 ± 9.7 (32-93) (P < .001). The mean postoperative SST was 9.1 ± 2.2 (1-12). Although the patients had lower postoperative abduction and internal rotation, strength in abduction and CMS in comparison with the measurements from the contralateral side, the median postoperative SF-36 physical and mental component summaries were 98% and 100% of the matched norms. No significant differences were found in postoperative outcomes according to the RCT pattern. Males showed significantly higher strengths in abduction (B = -1.384, 95% confidence interval [CI] -2.144 to -0.624, η2 = 0.123, P < .001, 95% power), external rotation (B = -3.646, 95% CI -5.2 to -2.092, η2 = 0.189, P < .001, 100% power), and internal rotation (B = -3.867, 95% CI -5.676 to -2.057, η2 = 0.162, P < .001, 99% power) than females. Significantly higher ranges of abduction (η2 = 0.431, P = .019, 98% power) and external rotation (η2 = 0.417, P < .03, 97% power) were noted in younger patients. Higher strengths in abduction (η2 = 0.495, P = .002, 100% power) and internal rotation (η2 = 0.464, P = .006, 99% power) were also reported in these patients. CONCLUSIONS: When there is an irreparable supraspinatus but there is still the possibility to repair the infraspinatus and subscapularis, the arthroscopic partial cuff repair should be considered as an effective surgical option. Indeed, a significant clinical improvement can be achieved and, differently from pure symptomatic surgical procedures, this technique represents a reasonable effort to restore, at least in part, the shoulder joint functionality. Successful and reliable results can be expected at an average 7-year follow-up, regardless of the RCT pattern. Female and older patients have a greater likelihood of lower functional outcomes. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Transient osteoporosis of the hip with a contralateral delayed involvement: a case report.

We describe a case of non-simultaneous bilateral hip pain with bone marrow edema occurring in an adult male, with the contralateral hip being involved 12 years later after the onset of symptoms. On the basis of clinical and imaging findings, together with a complete resolution after conservative management, a post-hoc diagnosis of metachronous bilateral transient osteoporosis of the hip (TOH) was made. Non-simultaneous bilateral presentation of TOH is exceptional, and contralateral involvement with a 12-year delay has never been previously described.

Hydatid cyst in the vastus lateralis muscle: a case report.

Hydatidosis is a zoonotic disease; human infection occurs through the consumption of food and water contaminated with the eggs of parasites of the Echinococcus type. While the liver is the most common site of infection, involvement of the musculoskeletal system is extremely rare. In the context of musculoskeletal involvement, the spine is the most commonly infected site, while the muscles are rarely infected and account for approximately <1% of cases. It has been suggested that muscles provide an unsuitable environment for the parasite, because of the presence of lactic acid. The cysts appear as slow-growing masses of soft tissue, and signs of inflammation and fistulization often coexist. We report a rare case of an hydatid cyst located in the vastus lateralis muscle of a 41-year-old man. Muscular echinococcosis is an extremely rare disease. A MRI evaluation should be taken into account as gold standard in the diagnosis. Surgical cystectomy is often indicated, and an excision with wide margins is mandatory to avoid the rupture of the cyst and anaphylaxis. Adjuvant pharmacological therapy is recommended to minimize the risk of recurrence.

Giant schwannoma of the foot: a case report and literature review.

A schwannoma is a rare, benign tumor originating from Schwann cells of peripheral nerve sheath. It commonly occurs in subjects between 20 and 50 years of age, and its malignant transformation is exceptional. While schwannomas usually affect the head and neck region, localization in the lower extremity is exceptionally rare, and even fewer cases have described schwannomas occurring in the foot. We report a case of a giant schwannoma of the foot diagnosed in a 65-year-old woman. A giant schwannoma of the foot is an extremely rare soft tissue tumor. MRI may allow an earlier diagnosis and provide valuable information about the size and possible bone invasion. This case report noted that a complete excision of the schwannoma may prevent the risk of local recurrence, regardless of its size.

Predictors of functional outcomes and recurrent shoulder instability after arthroscopic anterior stabilization.

PURPOSE: To investigate what factors might predict the results of arthroscopic stabilization for anterior shoulder instability. METHODS: One hundred and forty-three patients averaging 25 (15-58) years with traumatic anterior shoulder instability who underwent arthroscopic stabilization were reviewed at a median follow-up of 81 (24-172) months. Sixty-two (56.4 %) individuals were involved in contact sport activities, and there were 40 (30 %) patients who had only one dislocation prior to having surgery. Rowe score was measured preoperatively and at follow-up. RESULTS: Thirty-three (23.1 %) patients experienced recurrent instability 12 (1-120) months after surgery, and 15 of those underwent further surgery. There was a statistically significant lower risk of failure (p = 0.027) for patients who had a surgical procedure after only one episode of shoulder dislocation. Patients treated after the second or further episode of shoulder dislocation exhibited a mean odds ratio for failure of 3.8 (95 % confidence interval 1.2-11.6, p = 0.044) with regard to first-time dislocators. The Rowe score significantly improved from a preoperative value of 25 (5-55) to a postoperative value of 100 (40-100) (p < 0.001). A significantly higher postoperative Rowe score was found in patients older than 24 years of age at the operation (p = 0.011) and in patients with less than eight dislocations prior to surgery (p = 0.05). CONCLUSIONS: These results suggest that better functional results following arthroscopic stabilization can be expected in patients over 24 years of age and in those with a fewer number of dislocations preoperatively. A lower rate of recurrence can be expected if the patient undergoes surgery after the first episode of dislocation. LEVEL OF EVIDENCE: Prognostic study, Level II.

Functional status and failed rotator cuff repair predict outcomes after arthroscopic-assisted latissimus dorsi transfer for irreparable massive rotator cuff tears.

BACKGROUND: Arthroscopic-assisted latissimus dorsi tendon transfer (LDTT) has been recently introduced for treatment of irreparable, posterosuperior massive rotator cuff tears. We sought to evaluate the functional outcomes of this technique and to check for possible outcome predictors. METHODS: The study reviewed 86 patients (aged 59.8 ± 5.9 years) who underwent an arthroscopic-assisted latissimus dorsi tendon transfer after 36.4 ± 9 months of follow-up. Of these, 14 patients (16.3%) sustained an irreparable massive rotator cuff tear after a failed arthroscopic rotator cuff repair. The Constant and Murley score (CMS) was used to assess patients' functionality preoperatively and at follow-up. RESULTS: As a group, the CMS improved with surgery from 35.5 ± 6.1 to 69.5 ± 12.3 (P < .001). A lower preoperative CMS and a previous failed rotator cuff repair resulted in lower postoperative range of motion (P = .044 and P = .007, respectively) and CMS (P = .042 and P = .018, respectively). A previous rotator cuff repair resulted in lower satisfaction with surgery (P = .009). Gender and age did not affect the clinical outcomes. CONCLUSIONS: Our results support the effectiveness of arthroscopic-assisted LDTT in the treatment of patients with an irreparable, posterosuperior massive rotator cuff tears in pain relief, functional recovery, and postoperative satisfaction. Patients with lower preoperative CMS and a history of failed rotator cuff repair have a greater likelihood of having a lower clinical result. However, the favorable values of summary postoperative scores do not exclude these patients as candidates for arthroscopic-assisted LDTT.

Foundations of support constraint machines.

The mathematical foundations of a new theory for the design of intelligent agents are presented. The proposed learning paradigm is centered around the concept of constraint, representing the interactions with the environment, and the parsimony principle. The classical regularization framework of kernel machines is naturally extended to the case in which the agents interact with a richer environment, where abstract granules of knowledge, compactly described by different linguistic formalisms, can be translated into the unified notion of constraint for defining the hypothesis set. Constrained variational calculus is exploited to derive general representation theorems that provide a description of the optimal body of the agent (i.e., the functional structure of the optimal solution to the learning problem), which is the basis for devising new learning algorithms. We show that regardless of the kind of constraints, the optimal body of the agent is a support constraint machine (SCM) based on representer theorems that extend classical results for kernel machines and provide new representations. In a sense, the expressiveness of constraints yields a semantic-based regularization theory, which strongly restricts the hypothesis set of classical regularization. Some guidelines to unify continuous and discrete computational mechanisms are given so as to accommodate in the same framework various kinds of stimuli, for example, supervised examples and logic predicates. The proposed view of learning from constraints incorporates classical learning from examples and extends naturally to the case in which the examples are subsets of the input space, which is related to learning propositional logic clauses.

Clinical outcomes are unchanged after a mean of 12 years after reverse shoulder arthroplasty: a long-term re-evaluation.

Background: The medium-term results of reverse shoulder arthroplasty (RSA) that has been performed by a single surgeon have been previously reported. The purpose of this study was to investigate the minimum 10-year clinical and radiographic outcomes of these patients. Methods: In this prospective cohort study, 27 patients were evaluated after RSA for massive rotator cuff tear with or without eccentric osteoarthritis (OA) or concentric OA with the Constant-Murley Score (CMS), range of motion (ROM), and a radiologic assessment. Results: At a mean 12-year follow-up, the CMS and ROM were significantly improved when compared with the baseline values (all P < .001). Once stratified by diagnosis, no difference in the ROM or total CMS was found between patients with massive rotator cuff tear with/without eccentric OA and those with concentric OA. Neither ROM nor CMS decreased when compared to the mid-term values of the previous study, for both the overall population and the diagnosis-stratified groups. Scapular notching was reported in 66.7% of cases that was similar to the data reported at mid-term follow-up. The calcification rate was 59.3% at the long-term evaluation, and there were no differences between the same case-series population (51.9%; P = .785) and the whole population at mid-term follow-up (47%; P = .358). Conclusion: RSA led to excellent clinical and functional outcomes for patients up to 17 years postoperatively, and there was no decrease in the CMS over time. No loosening of implants was noted, and the rate of scapular notching was 66%, mostly grade 1 or 2.

Short- to Mid-Term Clinical and Radiological Results of Selective Laser Melting Highly Porous Titanium Cup in Primary Total Hip Arthroplasty.

(1) Background: The aim of this study was to evaluate short- to mid-term clinical and radiological results in patients undergoing primary total hip arthroplasty (THA) with the use of a Selective Laser Melting 3D-printed highly porous titanium acetabular cup (Jump System Traser®, Permedica Orthopaedics). (2) Methods: We conducted a retrospective study and collected prospective data on 125 consecutive patients who underwent primary THA with the use of highly porous titanium cup. Each patient was evaluated preoperatively and postoperatively with a clinical and radiological assessment. (3) Results: The final cohort consisted of 104 patients evaluated after a correct value of 52 (38-74) months. The median Harris Hip Score (HHS) significantly improved from 63.7 (16-95.8) preoperatively to 94.8 (38.2-95.8) postoperatively (p < 0.001), with higher improvement associated with higher age at surgery (ß = 0.22, p = 0.025). On postoperative radiographs, the average acetabular cup inclination and anteversion were 46° (30°-57°) and 15° (1°-32°), respectively. All cups radiographically showed signs of osseointegration with no radiolucency observed, or component loosening. (4) Conclusions: The use of this highly porous acetabular cup in primary THA achieved excellent clinical, functional, and radiological results at mid-term follow-up. A better clinical recovery can be expected in older patients. The radiological evaluation showed excellent osseointegration of the cup with complete absence of periprosthetic radiolucent lines.

Learning with boundary conditions.

Kernel machines traditionally arise from an elegant formulation based on measuring the smoothness of the admissible solutions by the norm in the reproducing kernel Hilbert space (RKHS) generated by the chosen kernel. It was pointed out that they can be formulated in a related functional framework, in which the Green's function of suitable differential operators is thought of as a kernel. In this letter, our own picture of this intriguing connection is given by emphasizing some relevant distinctions between these different ways of measuring the smoothness of admissible solutions. In particular, we show that for some kernels, there is no associated differential operator. The crucial relevance of boundary conditions is especially emphasized, which is in fact the truly distinguishing feature of the approach based on differential operators. We provide a general solution to the problem of learning from data and boundary conditions and illustrate the significant role played by boundary conditions with examples. It turns out that the degree of freedom that arises in the traditional formulation of kernel machines is indeed a limitation, which is partly overcome when incorporating the boundary conditions. This likely holds true in many real-world applications in which there is prior knowledge about the expected behavior of classifiers and regressors on the boundary.

Long-term follow-up results of the Cloward procedure for cervical spondylotic myelopathy.

PURPOSE: To assess the long-term results of anterior cervical discectomy and fusion using the Cloward procedure for the treatment of cervical spondylotic myelopathy, and to identify possible clinical outcome predictors. METHODS: A total of 14 cases with a 10-year postoperative follow-up were available (82.4 % of the surviving patients). Patients underwent preoperative and postoperative neurological examination. The symptom severity was graded according to the Nurick scale. MRI measurements were obtained preoperatively. Cervical spine radiographs were obtained preoperatively and at the time of follow-up. RESULTS: The mean improvement of the clinical status of patients on the Nurick scale was 1.43 ± 0.51 (range 1-2) with respect to the baseline values (p < 0.001), with a 62.5 % recovery rate. A positive association between the improvement of the Nurick scale and the length of follow-up was detected with an age-adjusted univariate analysis (p = 0.042). The Nurick grade improvement was also directly related to preoperative lower limb hyperreflexia (p = 0.039), spasticity (p = 0.017), and bladder dysfunction (p = 0.048). At the time of follow-up, an adjacent discopathy was noted above and below the operated level(s) in eight and six patients, respectively. CONCLUSIONS: The Cloward technique is a safe and effective procedure for the treatment of cervical spondylotic myelopathy. The patients' preoperative neurological status and the length of follow-up affect the grade of postoperative ambulatory improvement.

Health-related quality of life and functionality after reverse shoulder arthroplasty.

BACKGROUND: Modern semiconstrained reverse shoulder arthroplasty (RSA) has shown a great improvement in function and range of motion (ROM) in different etiologies, including revision surgery, sequelae of fractures, or tumors. Few studies have evaluated RSA for primary glenohumeral osteoarthritis, massive rotator cuff tear, or cuff tear arthropathy excluding any other shoulder disease, and data on patients' quality of life after this surgery are lacking. METHODS: In this prospective cohort study, 80 patients were evaluated after an RSA for either primary osteoarthritis, massive rotator cuff tear, or cuff tear arthropathy with the Constant-Murley score (CMS), ROM, and Short Form Health Survey (SF-36). A radiologic assessment was performed preoperatively and postoperatively in 62 of these patients. RESULTS: At a mean 5-year follow-up, the cumulative survival rate was 97.3% and significant improvements in the CMS and ROM were observed when compared with the baseline values. The CMS was 93.2% of the sex- and age-matched normal values. The postoperative SF-36 scores showed no significant differences compared with normative data. Younger patients and subjects with worse preoperative conditions achieved the greatest benefit after RSA. The length of follow-up was found to be associated with the severity of scapular notching. CONCLUSIONS: This study introduces new predictors for surgical outcomes, and it shows that patients who had undergone RSA a mean of 5 years earlier exhibit similar functionality and health-related quality of life with respect to healthy controls. Physicians should consider these results when discussing the outcomes of this surgery with patients. LEVEL OF EVIDENCE: Level IV, Case series, treatment study.

Midterm results and complications after minimally invasive distal metatarsal osteotomy for treatment of hallux valgus.

BACKGROUND: Minimally invasive distal metatarsal osteotomy (MIDMO) is a common technique used to correct the hallux valgus deformity, but controversy remains regarding the expected outcomes of this surgery. METHODS: Seventy-two patients (85 feet) suffering from hallux valgus underwent MIDMO with a modified Bösch technique. Patients were prospectively evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) hallux score, and the AOFAS recovery rate was calculated. Before surgery and at follow-up, the hallux valgus (HVA), intermetatarsal (IMA), and distal metatarsal articular (DMAA) angles were measured, and the severity of disease was categorized according to the preoperative HVA. The tibial sesamoid position and articular congruence were evaluated. Postoperative complications were noted. RESULTS: After an average follow-up of 73.3 ± 38.1 months, the total AOFAS score improved from 47.6 ± 13.3 to 87.3 ± 11.5 (P < .001). The HVA decreased from 34.7 ± 8.2 to 14.8 ± 7.8 degrees, the IMA from 14.7 ± 4 to 6.6 ± 3.6 degrees, and the DMAA from 20.9 ± 9.8 to 9 ± 6.6 degrees (P < .001 for all). Postoperative improvement in AOFAS was inversely related to the preoperative severity of disease (P < .001, ß = -.378). Sixteen (18.8%) deformity recurrences were noted, 9 of which were observed in patients with preoperative HVA more than 40 degrees. Worse preoperative congruence of the metatarsophalangeal joint and tibial sesamoid position correlated with a higher rate of recurrence of the disease after surgery (P = .001, ß = -.353 and P < .001, ß = .427, respectively). CONCLUSIONS: Satisfactory clinical and radiological results can be expected after MIDMO, but caution should be exercised when using this technique because of the likelihood of possible complications (29.4% overall complication rate). Predictors of surgical outcomes can be used to select the best candidates for this surgery. LEVEL OF EVIDENCE: Level IV, case series.