Sealed osteons in animals and humans: low prevalence and lack of relationship with age.

Sealed osteons are unusual variants of secondary osteons that have received little attention, especially in non-human bones. Sealed osteons are characterized by central canals that are plugged with bone tissue. As with other variants of secondary osteons (e.g. drifting, dumbbell, multi-canal), understanding how and why sealed osteons form can shed light on the mechanisms that regulate normal bone remodeling and how this process can be perturbed with aging and some diseases. In a recent microscopic evaluation of human tibiae obtained after traumatic amputations, 4-5% of the osteons were sealed. It is suggested that this high prevalence reflects occasional localized microscopic ischemia from normal osteonal remodeling; hence sealed osteons are implicated in human skeletal fragility. Therefore, osteon prevalence would be expected to correlate with the bone remodeling seen with aging; for example, showing positive relationships between sealed osteons and the population density of typical secondary osteons (OPD). We evaluated the prevalence of partially sealed (80-99% sealed) and fully sealed osteons with respect to age and variations in OPD in 10 adult human femora (34-71 years) and in various non-human appendicular bones of mature animals that were not of advanced age, including deer calcanei, equine radii and equine third metacarpals. An additional sample of 10 bilateral human femora with unilateral non-cemented total hip replacements (F,+HR) and non-implanted contralateral femora (F,-HR) were evaluated (10 patients; 52-94 years). In non-human bones, sealed + partially sealed osteons were rare (~0.1%) even when having relatively high OPD. When considering sealed + partially sealed osteons in femora from patients without any HR, results showed that 1.6% of the osteons were sealed or partially sealed, which was much lower than anticipated, but this is 10- to 20-fold more than in any of the non-human bones. Additionally, in all bones, sealed + partially sealed osteons were significantly smaller than typical secondary osteons (mean diameters: 125 vs. 272 µm; P < 0.005). In the patients with HR, the percentage of sealed + partially sealed osteons: (i) did not correlate with age, (ii) showed no significant difference between F,-HR and F,+HR (1.9 vs. 2.1%; P = 0.2), and (iii) was positively correlated with OPD (r = 0.67, P = 0.001), which differs from the very weak or lack of correlations in the non-human bones and the other human femur sample. The lack of an age-related relationship, in addition to the very low prevalence of sealed + partially sealed osteons are inconsistent with the idea that they contribute to reduced bone quality seen in aging humans. The small size of sealed and partially sealed osteons, regardless of species affiliation, suggests that they represent closing cones at the termini of some osteons. Available evidence suggests that osteons of primates might have a greater capacity for branching that is associated with closing cones, which might explain the 10-20 times higher prevalence of sealed + partially sealed osteons in the human bones examined in this study.

Preoperative Imaging of Temporoparietal Scalp Thickness Predicts Off-the-Ear Sound Processor Retention in Cochlear Implants With Diametric Magnets.

OBJECTIVE: To determine if temporoparietal scalp thickness assessed via preoperative imaging predicts retention events in patients who have cochlear implants with diametric magnets and various sound processor types. STUDY DESIGN: Retrospective chart and radiological review. SETTING: Tertiary referral center. PATIENTS: One hundred forty-three adult patients who have cochlear implants with diametric magnets. MAIN OUTCOME MEASURES: Skin flap thickness, retention events, body mass index (BMI), and magnet strength. RESULTS: Of 42 patients with the most recent generation off-the-ear sound processor (OTE2), 13 (31.0%) had retention events. Of patients with a temporoparietal scalp thickness less than 8 mm, all patients could ultimately retain the device, though one of 26 was noted to have tenuous retention. Of patients with 8 to 10 mm skin flaps, 3 of 6 (50%) could not retain the device, and with more than 10 mm skin flaps, 7 of 10 (70%) could not retain the device. In the more than 10 mm group, two additional patients could not either retain the device at initial activation or were noted to have tenuous retention. Of 124 patients with behind-the-ear (BTE) sound processors, only 2 (1.6%) could not retain the device at initial activation, and 3 (2.4%) exhibited tenuous retention after 3 months of device use. Results from the first generation off-the-ear sound processor (OTE1) are also reported. CONCLUSIONS: Temporoparietal scalp thickness measured by preoperative imaging is associated with processor retention for patients with the OTE2 sound processor and diametric magnets. All patients with less than 8 mm scalp thickness could retain the OTE2, while 50% of patients with 8 to 10 mm scalp thickness and 70% with more than 10 mm scalp thickness could not retain the device. Patients should be counseled regarding their sound processor choice and/or considered candidates for skin flap reduction or other intervention as indicated. Retention events with BTE processors are rare.

Sarcoid of the Upper Humerus Found Incidentally on MR Images Obtained for Work-Up of Rotator Cuff Tear Where Compromised Tissue Quality Was a Concern for Surgical Success.

Sarcoidosis is an idiopathic systemic inflammatory disorder characterized histologically by noncaseating granulomas. The pathogenesis likely includes genetic, immunologic, and environmental factors. The lungs, skin, and eyes are most commonly affected. Although bone involvement is possible, sarcoidosis of the humerus is rare, with few cases reported. Furthermore, we are unaware of any reports of sarcoidosis of the upper humerus with a coexisting rotator cuff tear. We report the case of a 50-year-old female with sarcoidosis of the humerus and a coexisting tear of the supraspinatus tendon. Her medical history includes type 2 diabetes, depression, and fatigue. She had chronic shoulder pain that worsened after her dog jerked on the leash. Radiographs were grossly normal. Subsequent magnetic resonance imaging (MRI) demonstrated a possible small full-thickness rotator cuff tear. Multiple rounded lesions were also noted within the proximal humerus. A biopsy demonstrated noncaseating granulomas, confirming the diagnosis of sarcoidosis. There was concern that her sarcoid lesions would compromise bone quality, limiting options for surgical repair of her rotator cuff tear. However, it was determined that her lesion did not involve cortical bone, and surgery was performed. During surgery, the supraspinatus tendon was found to be partially torn and was treated with arthroscopic debridement and acromioplasty. An excellent result was ultimately achieved after her rheumatologist started adalimumab injections. This case demonstrates that there can be a rare incidental finding of osseous sarcoid lesions in the upper humerus where the bone might be compromised in the location of a planned rotator cuff repair.

Rotator cuff tear following long-standing axillary neuropathy in a female motocross racer.

A 'terrible triad' of anterior shoulder dislocation, axillary nerve damage and rotator cuff tear has been previously described. However, we are unaware of any report of anterior shoulder dislocation, humeral fracture, axillary neuropathy and subsequent rotator cuff tear requiring surgery when the axillary neuropathy was deemed permanent. We report the case of a 20-year-old woman who fell in a motocross accident and had an anterior shoulder dislocation, humeral fracture and axillary neuropathy. The fracture was treated surgically with open reduction and internal fixation. The axillary nerve injury was ultimately permanent. Thirteen months after the motocross accident, the patient sustained a rotator cuff tear from seemingly minor trauma. However, several months of aggressive physical therapy preceded the rotator cuff tear. The tear was repaired and the patient was followed for 5 years after the initial injury. She returned to competing in motocross, even though the axillary neuropathy remained complete and permanent.

Latissimus Dorsi Tendon Transfer with GraftJacket® Augmentation to Increase Tendon Length for an Irreparable Rotator Cuff Tear.

Massive irreparable rotator cuff tears can be reconstructed with latissimus dorsi tendon transfers (LDTT). Although uncommon, the natural length of the latissimus dorsi tendon (LDT) could be insufficient for transfer even after adequate soft tissue releases. Descriptions of cases where grafts were needed to lengthen the LDT are therefore rare. We located only two reports of the use of an acellular dermal matrix to increase effective tendon length in tendon transfers about the shoulder: (1) GraftJacket patch for a pectoralis major tendon reconstruction and (2) ArthroFlex® patch for LDTT. Both of these brands of allograft patches are obtained from human cadavers. These products are usually used to cover soft tissue repairs and offer supplemental support rather than for increasing tendon length. Extending the LDTT with GraftJacket to achieve adequate length, to our knowledge, has not been reported in the literature. We report the case of a 50-year-old male who had a massive, irreparable left shoulder rotator cuff tear that was reconstructed with a LDTT. The natural length of his LDT was insufficient for transfer. This unexpected situation was rectified by sewing two patches of GraftJacket to the LDT. The patient had greatly improved shoulder function at two-year follow-up.

Delaying shoulder motion and strengthening and increasing achilles allograft thickness for glenoid resurfacing did not improve the outcome for a 30-year-old patient with postarthroscopic glenohumeral chondrolysis.

Although interposition soft-tissue (biologic) resurfacing of the glenoid with humeral hemiarthroplasty has been considered an option for end-stage glenohumeral arthritis, the results of this procedure are highly unsatisfactory in patients less than 40 years old. Achilles tendon allograft is popular for glenoid resurfacing because it can be made robust by folding it. But one reason that the procedure might fail in younger patients is that the graft is not initially thick enough for the young active patient. Most authors report folding the graft only once to achieve two-layer thickness. We report the case of a 30-year-old male who had postarthroscopic glenohumeral chondrolysis that was treated with Achilles tendon allograft resurfacing of the glenoid and humeral hemiarthroplasty. An important aspect of our case is that the tendon was folded so that it was 50-100% thicker than most allograft constructs reported previously. We also used additional measures to enhance allograft resiliency and bone incorporation: (1) multiple nonresorbable sutures to attach the adjacent graft layers, (2) additional resorbable suture anchors and nonresorbable sutures in order to more robustly secure the graft to the glenoid, and (3) delaying postoperative motion and strengthening. However, despite these additional measures, our patient did not have an improved outcome.