Humeral head size predicts baseplate lateralization in reverse shoulder arthroplasty: a comparative computer model study.

Background: In reverse shoulder arthroplasty (RSA), the ideal combination of baseplate lateralization (BL), glenosphere size (GS), and glenosphere overhang (GOH) with a commonly used 145° neck shaft angle (NSA) is unclear. This is the first study evaluating correlations of body height (BH), humeral head size (HS), glenoid height (GH), and association of gender with best glenoid configurations for range of motion (ROM) maintaining anatomic lateralization (aLAT) for optimized muscle length in 145° and less distalized 135° RSA. Methods: In this computer model study, 22 computed tomographies without joint narrowing were analyzed (11 male/female). A standardized semi-inlay 145° platform stem was combined with 20 glenoid configurations (baseplate [B] 25, 25 + 3/+6 lateralized [l], 29, 29 + 3/6l combined with glenosphere 36, 36 + 2 eccentric [e], 36 + 3l, 39, 39 + 3e, 39 + 3l , 42, 42 + 4e). Abduction-adduction, flexion-extension, external rotation-internal rotation, total ROM (TROM), and total notching relevant (TNR) ROM were computed, best TROM models respecting aLAT (-1 mm to +1 mm) and HS/GH recorded. Second, the 145° models (Ascend Flex stem; Stryker, Kalamazoo, MI, USA) were converted and compared to a 135° inlay RSA (New Perform stem; Stryker, Kalamazoo, MI, USA) maintaining GOH (6.5-7 mm) and aLAT. Results: Best 145° models had eccentric glenospheres (mean BL: 3.5 mm, GOH 8.8 mm, GS 38.1 mm, distalization 23 mm). The 135° models had concentric glenospheres, mean BL 3.8 mm, GOH 6.9 mm, GS 39.7 mm, and distalization 14.1 mm. HS showed the strongest positive correlation with BL in 145° and 135° models (0.65/0.79). Despite reduced GOH in smaller females with a 135° NSA, adduction, external rotation, extension, TNR ROM, and TROM were significantly increased (P = .02, P = .005, P = .005, P = .004, P = .003), abduction however reduced (P = .02). The same trends were seen for males. Conclusion: HS is a practical measure in surgery or preoperatively, and the strong positive correlation with BL is a useful planning aid. Despite reduction of GOH, conversion to a less distalized 135° NSAinlay design is powerful to maintain and even significantly increase all components of TNR ROM (extension/external rotation/adduction) in small females with the drawback of reduced abduction which may however be compensated by scapula motion. Lateralization with a less distalized 135° RSA optimizes muscle length, may facilitate subscapularis repair, and maintains highest rigid body motion.

Influence of the anatomy of the proximal articular surface of the trapezium (PAST) and the trapezoidal articular surface of the trapezium (TRAST) in cup placement during trapeziometacarpal arthroplasty.

The influence of the anatomy of the proximal articular surface of the trapezium (PAST) and the trapezoidal articular surface of the trapezium (TRAST) on cup placement during trapeziometacarpal arthroplasty was retrospectively evaluated on 56 preoperative anteroposterior radiographs of patients who underwent surgery for trapeziometacarpal osteoarthritis. The percentage coverage of the prosthetic cup by the PAST and the available height of the trapezium were calculated. In 39% of cases, there was a significant difference (up to a mean 4.5 mm, p < 0.001) between the radial height of the trapezium (which is usually considered) and the available height of the trapezium. The anatomy of the PAST and the TRAST has an impact on the placement of the prosthetic cup when trapezium height is low. The results of the present study suggest that these considerations must be known by all operators performing trapeziometacarpal arthroplasty; that lateralization, implant suspension, or surgical alternatives should be considered to prevent several intra- and postoperative surgical complications. Level of evidence: IV.

Are glenoid retroversion, humeral subluxation and Walch classification associated with a muscle imbalance.

INTRODUCTION: The etiology of humeral posterior subluxation remains unknown, and it has been hypothesized that horizontal muscle imbalance could cause this condition. The objective of this study was to compare the ratio of anterior to posterior rotator cuff muscle and deltoid volumes as a function of humeral subluxation and glenoid morphology when analyzed as continuous variable in arthritic shoulders. METHODS: Three hundred and thirty-three (273 arthritic and 60 healthy controls) CT-scans of shoulders were included in this study and were segmented automatically. For each muscle, the volume of muscle fibers without intra-muscular fat was then measured. The ratio between the volume of the subscapularis and the volume of the infraspinatus + teres minor (AP ratio) and the ratio between the anterior and posterior deltoid (APdeltoid) were calculated. Statistical analyses were performed to determine whether a correlation could be found between these ratios and glenoid version/ humeral subluxation/glenoid type in the Walch classification. RESULTS: Within the arthritic cohort, no statistically significant difference was found between the AP ratio between A and type B glenoids (1.09 ± 0.22 versus 1.03 ± 0.16 p=0.09), between A and D type glenoids (1.09 ± 0.22 versus 1.12 ± 0.27, p=0.77) nor between the A and C type glenoids (1.09 ± 0.22 versus 1.10 ± 0.19, p=1). No correlation was found between AP ratio and glenoid version/humeral subluxation (rho =-0.0360, p=0.55; rho = 0.076; p=0.21). The APdeltoid ratio of type A glenoids was significantly greater than that of type B glenoids (0.48 ± 0.15 versus 0.35 ± 0.16, p< 0.01), and type C glenoids (0.48 ± 0.15 versus 0.21±0.10, p < 0.01) but not significantly different from the APdeltoid ratio of type D glenoids (0.48 ± 0.15 versus 0.64 ± 0.34, p=1). When evaluating both healthy control and arthritic shoulders, moderate correlations were found between APdeltoid ratio and glenoid version/humeral subluxation (rho=0.55, p<0.01; rho=-0.61, p<0.01). CONCLUSION: This in vitro study supports the use of a software for fully automated 3D reconstruction of the four rotator cuff muscles and the deltoid. Compared to previous two-dimensional CT-scan studies, we did not find any correlation between AP muscle volume ratio and glenoid parameters in arthritic shoulders. However, once deformity occurred, the observed APdeltoid ratio was lower with Type B and C glenoids. These findings suggest that rotator cuff muscle imbalance may not be the precipitating etiology for the posterior humeral subluxation and secondary posterior glenoid erosion characteristic of Walch B glenoids.

Premorbid glenoid anatomy reconstruction from contralateral shoulder 3-dimensional measurements: a computed tomography scan analysis of 260 shoulders.

BACKGROUND: Total shoulder arthroplasty (TSA) aims to reconstruct the premorbid anatomy of a pathologic shoulder. A healthy contralateral shoulder could be useful as a template in planning TSA. The symmetry between the left and right shoulders in healthy patients remains to be proved. The purpose of this study was to compare the 3-dimensional anatomy of the glenoid between sides in a healthy population. METHODS: A multinational computed tomography scan database was retrospectively reviewed for all healthy bilateral shoulders in patients aged between 18 and 50 years. One hundred thirty pairs of healthy shoulder computed tomography scans were analyzed, and glenoid version, inclination, width, and height, as well as glenoid lateral offset and scapula lateral offset, were measured. All anatomic measures were computed with Blueprint, validated 3-dimensional planning software. The intraclass correlation coefficient was determined for each measure between left and right shoulders. The minimal detectable change (MDC) was calculated using the following formula: MDC=2×1.96×Standarderrorofmeasurement. RESULTS: The comparison between 130 pairs of healthy scapulae showed statistically significant differences in absolute values between right and left glenoid version (-5.3° vs. -4.6°, P < .01), inclination (8.4° vs. 9.3°, P < .01), and width (25.6 mm vs. 25.4 mm, P < .01), as well as scapula offset (105.8 mm vs. 106.2 mm, P < .01). Glenoid height was comparable between right and left shoulders (33.3 mm vs. 33.3 mm, P = .9). The differences between the means were always inferior to the MDC regarding glenoid version, inclination, height, and width, as well as scapula offset. Very strong intraclass correlation coefficients between the left and right shoulders were found for all evaluated paired measures. CONCLUSION: Healthy contralateral scapulae are highly reliable to predict inclination, height, width, and scapula offset and are reliable to predict version of a given scapula. Paired right and left scapulae were not statistically symmetrical regarding mean glenoid version, inclination, and width, as well as scapula offset. Nevertheless, the reported differences were not higher than the MDC for this cohort, confirming that healthy contralateral shoulders can be a useful template in TSA preoperative planning.

Are glenoid retroversion, humeral subluxation and Walch classification associated with a muscle imbalance.

INTRODUCTION: The etiology of humeral posterior subluxation remains unknown, and it has been hypothesized that horizontal muscle imbalance could cause this condition. The objective of this study was to compare the ratio of anterior to posterior rotator cuff muscle and deltoid volumes as a function of humeral subluxation and glenoid morphology when analyzed as continuous variable in arthritic shoulders. METHODS: Three hundred and thirty-three (273 arthritic and 60 healthy controls) CT scans of shoulders were included in this study and were segmented automatically. For each muscle, the volume of muscle fibers without intra-muscular fat was then measured. The ratio between the volume of the subscapularis and the volume of the infraspinatus + teres minor (AP ratio) and the ratio between the anterior and posterior deltoid (APdeltoid) were calculated. Statistical analyses were performed to determine whether a correlation could be found between these ratios and glenoid version/ humeral subluxation/glenoid type in the Walch classification. RESULTS: Within the arthritic cohort, no statistically significant difference was found between the AP ratio between A and type B glenoids (1.09 ± 0.22 versus 1.03 ± 0.16 p=0.09), between A and D type glenoids (1.09 ± 0.22 versus 1.12 ± 0.27, p=0.77) nor between the A and C type glenoids (1.09 ± 0.22 versus 1.10 ± 0.19, p=1). No correlation was found between AP ratio and glenoid version/humeral subluxation (rho =-0.0360, p=0.55; rho = 0.076; p=0.21). The APdeltoid ratio of type A glenoids was significantly greater than that of type B glenoids (0.48 ± 0.15 versus 0.35 ± 0.16, p< 0.01), and type C glenoids (0.48 ± 0.15 versus 0.21±0.10, p < 0.01) but not significantly different from the APdeltoid ratio of type D glenoids (0.48 ± 0.15 versus 0.64 ± 0.34, p=1). When evaluating both healthy control and arthritic shoulders, moderate correlations were found between APdeltoid ratio and glenoid version/humeral subluxation (rho=0.55, p<0.01; rho=-0.61, p<0.01). CONCLUSION: As opposed to previous two-dimensional CT scan studies, we did not find any correlation between AP muscle volume ratio and glenoid parameters in arthritic shoulders. Therefore, rotator cuff muscle imbalance does not seem to be associated with posterior humeral subluxation leading to posterior glenoid erosion and subsequent retroversion characteristic of Walch B glenoids. However, our results could suggest that a larger posterior deltoid pulls the humerus posteriorly into posterior subluxation, but this requires further evaluation as the deltoid follows the humerus possibly leading to secondary asymmetry between the anterior and the posterior deltoid.

Technique for Surgical Dissection and Histological Investigation of the Anterolateral Ligament in the Fetal Knee.

There is growing evidence into the structure and function of the anterolateral ligament (ALL) of the knee. However, debate still exists about the anatomical characteristics, biomechanical role, and even the existence of the ALL, despite numerous cadaveric, biomechanical, and clinical studies. This article describes, with video illustration, the surgical dissection of the ALL in human fetal lower limbs, including determination of detailed anatomical and histological features of the ALL during fetal development. The ALL was clearly identified in dissected fetal knees, and histologic analysis shows well-organized, dense collagenous tissue fibers with elongated fibroblasts, consistent with the properties of a ligament.

Long-term patient-reported outcome measures of fingertip coverage with a homodigital unipedicle neurovascular island flap.

We report the long-term patient-reported outcomes and objective outcomes of a homodigital neurovascular island flap for distal phalangeal amputations in the fingers (with the thumb excluded) for 20 patients at a median follow-up of 4.4 years (IQR 2.2 to 12.3). We assessed the global subjective and aesthetic outcomes, range of motion, sensitivity and strength. The patient-reported median subjective global score was 7.5/10 points (IQR 7 to 9) and the aesthetic score was 8/10 points (IQR 8 to 9). Range of motion, sensitivity and strength were similar to the uninjured side. Stiffness was present in more than half of the cases; 14 patients had a hook nail deformity and seven patients reported symptomatic cold intolerance. At a long-term follow-up, the patient-reported outcome measures and objective outcomes of this flap are satisfactory and it is a safe and reliable flap.Level of evidence: IV.

Role of middle glenohumeral ligament in external shoulder rotation.

Background: The middle glenohumeral ligament (MGHL) is one of the three ligaments that stabilize the anterior capsule of the shoulder. Recent work suggests that it inserts distally into the deep layer of the subscapularis tendon. The role of the MGHL remains debated. The hypothesis of this study was that the MGHL plays a significant functional role in limiting external rotation of the shoulder while allowing a wide range of motion through its distal insertion into the subscapularis rather than directly onto the humerus. Methods: In a cadaveric study performed on 20 shoulders (10 subjects), the MGHL and the other anterior structures of the shoulder were successively cut according to a standardized protocol. At each stage, the external rotation range of the shoulder was measured with the arm at the side (ER 1) and in 90° abduction (ER 2) using a goniometer. After dissection, the structure of the MGHL and its distal insertion were analyzed. Results: Cutting the MGHL led to significant increases in ER 1 but not in ER 2. Shoulder range of motion in ER 1 increased on average by 15 ± 5° (P < .001) after cutting the MGHL and by 21 ± 11° (P < .001) after subscapularis peel. The range of motion in ER 2 increased by 3 ± 4° (P = .048) after cutting the MGHL, by 4 ± 6° (P = .02) after subscapularis peel and by 25 ± 8° (P < .001) after cutting the inferior glenohumeral ligament. The MGHL was present in all dissected shoulders. It was leaf-like in 12 cases, cord-like in 6 cases and had a vestigial appearance in 2 cases. The distal insertion was in all cases in the deep layer of the subscapularis in a thickening of the anterior capsule in the superior part of the muscle, except for two cases in which the tendinous part of the subscapularis was also involved. Conclusion: The MGHL limited shoulder external rotation by a similar amount as the subscapularis muscle. Further studies are required to understand the clinical relevance of these findings, notably for the treatment of shoulder stiffness.

Intraoperative modification of total elbow arthroplasty implants.

BACKGROUND: Modification of total elbow arthroplasty (TEA) implants may be necessary in selected patients with substantial anatomic bone deformity or those undergoing revision surgery. The purpose of this study was to investigate the prevalence and consequences of implant modifications during TEA at our institution. We hypothesized that TEA implant modification would be more common in revisions than in primary replacements, and that it would not be associated with worse clinical outcomes or increased rates of radiographic or surgical complications directly related to the implant modification. METHODS: Elbows that had undergone TEA by any of 3 surgeons at our institution with use of intraoperative implant modification between January 1992 and October 2019 were retrospectively reviewed for the type of modification and complications. Complications were classified as definitely related, probably related, possibly related, or nonrelated to the implant's modification according to the consensus review by the 3 senior surgeons. A survey was sent out to surgeons outside of our institution to investigate whether intraoperative modification to TEA implants is a common clinical practice. RESULTS: A total of 106 implant components were modified during 94 of 731 TEA procedures (13%) in 84 of 560 patients. Implant modifications were performed in 60 of 285 revision cases (21%) compared with 34 of 446 (8%) primary cases (P < .0001). These included shortening the stem in 40 (44%), bending the stem in 16 (15%), notching the stem in 16 (15%), tapering the stem in 9 (9%), and a combination of 2 or more of these modifications in 19 implants (17%). Among the 55 index surgeries available for complication analysis, 40 complications occurred in 28 index surgeries (11 primary and 17 revisions; 25 patients), making the overall complication rate 51%. Of these 40 complications, 23 were considered independent of any implant modification. Of the remaining 17 complications, 9 were considered nonrelated to the implant modification, 6 were possibly related, and 2 were probably related to the implant modification. Therefore, the complication rate possibly related or probably related to implant modification was 15% (8 of 55). No complication was classified as definitely related to the implant modification. No implant breakage or malfunction occurred after any modification. A total of 442 survey responses were received representing 29 countries, of which 144 surgeons (39%) performed modification to implants during TEA procedures. DISCUSSION: This study confirmed our hypothesis that modification of TEA implants is not uncommon at our institution, particularly in revision arthroplasty. Surgeons should keep in mind that complications possibly related or probably related to implant modification were at minimum 15% and could have been as high as 30% if the patients lost to follow-up had all had complications. Implant modification may be necessary in some cases but should be exercised with thoughtful consideration and caution.

Hemi-reverse revision arthroplasty in the setting of severe glenoid bone loss.

BACKGROUND: Glenoid bone loss is one of the main challenges in revision of failed shoulder arthroplasties. The concept of a hemi-reverse procedure is to implant a glenoid baseplate and glenosphere to protect the glenoid reconstruction to allow it to heal and to preserve the joint space for a potential second-stage humeral component implantation. The purpose of this study was to report the results of hemi-reverse procedures. METHODS: Revision to a hemi-reverse procedure was performed in 15 patients: 8 with a failed anatomic total shoulder arthroplasty, 3 with a failed reverse shoulder arthroplasty, 3 with a failed humeral hemiarthroplasty, and 1 with placement of a cement spacer owing to sepsis after a total shoulder arthroplasty. After complete removal of the initial prosthesis, all patients underwent glenoid reconstruction with bone grafting and implantation of a reverse arthroplasty baseplate and glenosphere. A humeral implant was not placed in any case. The patients were prospectively followed up and underwent complete clinical and radiologic studies preoperatively and postoperatively at a minimum of 2 years after the surgical procedure. RESULTS: Thirteen hemi-reverse implants and glenoid bone grafts healed (86%) and remained radiographically stable. One hemi-reverse construct migrated and became mechanically loose, which was attributed to absent fixation of the central post in the native glenoid bone. In 1 patient, an implant-related infection developed; irrigation and debridement were performed, in addition to revision to a resection arthroplasty. After documented radiographic healing of the hemi-reverse glenoid reconstruction, 5 patients underwent a second-stage revision to a reverse procedure with insertion of a humeral component at a median of 6 months (interquartile range [IQR], 6-8 months). In this group, the median follow-up period was 73 months (IQR, 45-153 months), the median Constant score was 48 (IQR, 41-56), median active forward elevation was 135° (IQR, 100°-150°), and the median Subjective Shoulder Value was 50% (IQR, 50%-60%). In the group of 9 patients with remaining hemi-reverse implants, the median follow-up period was 38 months (IQR, 29-60 months), the median Constant score was 41 (IQR, 38-46), median active forward elevation was 100° (IQR, 80°-100°), and the median Subjective Shoulder Value was 50% (IQR, 40%-60%). CONCLUSION: The hemi-reverse procedure is an effective revision procedure to reconstruct a severely deficient glenoid. The hemi-reverse procedure may function as the definitive procedure, with satisfactory outcomes. Additionally, in patients who undergo the hemi-reverse procedure, second-stage revision to a total reverse procedure can be performed once imaging confirms bone graft and construct stability.

Computed tomography analysis of the relationship between the coronoid and the radial head.

BACKGROUND: The coronoid process is an important stabilizer of the elbow, and its anatomy has been extensively studied. However, data documenting the relationship of the coronoid relative to the radial head (RH) are limited. The latter is a good landmark for the surgeon when débriding or reconstructing the coronoid. This imaging-based study quantified the anatomic relationship between the coronoid and the proximal radius and ulna. METHODS: We investigated 80 cadaveric upper extremities (18 paired elbows) by 3-dimensional digital analysis of computed tomography data. After construction of a standardized coordinate system, the relationships between the coronoid, the anterior-most point of the RH, the deepest point of the articular surface of the RH, the top of the lesser sigmoid notch, and the deepest point of the guiding ridge of the trochlear notch were analyzed. RESULTS: The mean height of the tip of the coronoid was 36 ± 4 mm (range, 26-43 mm). The mean height of the anterior-most point of the RH was 40 ± 4 mm (range, 28-47 mm). The mean distance between the tip of the coronoid and the anterior-most point of the RH was 4.5 ± 1 mm (range, 2-10 mm). For paired elbows, the heights of the tip of the coronoid and the anterior-most point of the RH were similar between sides. CONCLUSION: This study described the relationship between the coronoid and RH. This information should prove useful when reconstructing a coronoid from a medial approach in the case of an intact RH. The difference in radiographic height between the tip of the coronoid and anterior RH in the normal elbow averages 5 mm. However, when we account for the normal cartilage thickness of the RH and coronoid, a 3- to 6-mm difference in height would be seen at surgery depending on whether the cartilage of the coronoid process is intact or removed. The distance between the tip of the coronoid and the anterior-most point of the RH is similar to the size of shavers used when débriding osteophytes during arthroscopy.

Ultrasound Evaluation of the Protector Role of the Pronator Quadratus Suture in Volar Plating.

The main complication of volar locking plates for distal radius fractures is flexor tendon rupture. The flexor pollicis longus (FPL) is the most commonly ruptured. Repair of the pronator quadratus (PQ) is one of the ways to prevent tendon rupture. The main purpose of this series was to evaluate the role of PQ repair after volar plating to prevent flexor tendon rupture using ultrasound (US). This work was a mono-operator prospective series of 20 consecutive patients with volar locking plates for distal radius fracture between September 2014 and May 2015. The PQ was repaired in all patients. A clinical, ultrasound, and perioperative evaluation of the flexor tendon was performed by this same surgeon. There was no flexor tendon rupture or tenosynovitis. There were no type A cases, which are characterized by contact between the plate and the FPL, and mostly type C cases, which are characterized by no contact between the plate and the FPL on US imaging. The suture of the PQ was sustainable over time when we removed the plate. Pronator quadratus repair is one of the ways to prevent flexor tendon rupture after volar plating. The outward-running suture is an effective technique for repairing the PQ. Ultrasound may be helpful during follow-up to detect asymptomatic flexor tendon irritation.

Bipolar transfer of the pectoralis major muscle for restoration of elbow flexion in 29 cases.

BACKGROUND: This study evaluated the functional outcomes of bipolar pedicled pectoralis major (PM) transfer to restore elbow flexion. METHODS: We retrospectively reviewed 29 transfers in 28 patients with a mean age of 31.2 years (range, 5-65 years). The loss of elbow flexion was due to brachial plexus palsy in 24 patients, elbow flexors necrosis in 4, and poliomyelitis in 1. The entire PM muscle was mobilized and fixed proximally to the coracoid process. Intraoperative positioning and postoperative immobilization of the shoulder and the elbow flexed at 60° and 120°, respectively, allowed direct distal fixation of the muscle to the biceps brachii tendon. RESULTS: At the last follow-up (mean, 13 months; range, 4-37 months), 41% of the transfers (n = 12) recovered grade 4 elbow flexion strength and were able to lift 2.2 kg on average (range, 0.5-5 kg), 52% (n = 15) recovered grade 3 strength, and 7% (n = 2) had a poor result (ie, grade 2 elbow flexion). The mean active elbow flexion was 100° (ranging, 30°-150°), and the patients had 0° to 10° elbow flexion contracture. CONCLUSIONS: Our results indicate that bipolar PM transfer is a reliable and effective procedure to restore elbow flexion. Flexion of the shoulder and elbow allowed the transfer to reach the elbow fold and avoided an interposition graft between the distal PM and the biceps brachii tendon.

Wrist hemiarthroplasty for irreparable DRF in the elderly.

INTRODUCTION: The authors update their results of wrist hemiarthroplasty for irreparable distal radius fracture in the elderly, at a minimum of 2-year follow-up. MATERIALS AND METHODS: Between 2011 and 2018, 25 consecutive independent elderly patients (24 female, 27 wrists) were treated with wrist hemiarthroplasty for distal radius fracture at a single institution. The average age was 77 years (range 65-88). They all were independent at home. A total of 19 wrists were treated at the acute stage, and 8 secondary procedures. The average follow-up was 32 months (range 24-44). RESULTS: There was no dislocation, loosening, infection nor removal of the implants. We observed 3 CRPS. At final follow-up, the average VAS pain was 1/10, mean forearm pronation/supination arc was 150°, and mean active flexion-extension arc was 60°. Average wrist extension was 36°. Mean grip strength was 68% of contralateral side. Mean Lyon wrist score was 74%. Mean Quick DASH score was 26%, and mean PRWE score was 25%. DISCUSSION: Our data suggest that treatment of acute irreparable distal radius fracture in the independent elderly patient with a bone-preserving primary wrist hemiarthroplasty may be a viable option. Longer-term follow-up are needed to confirm these preliminary data.