Strain-mode-specific mechanical testing and the interpretation of bone adaptation in the deer calcaneus.

The artiodactyl (deer and sheep) calcaneus is a model that helps in understanding how many bones achieve anatomical optimization and functional adaptation. We consider how the dorsal and plantar cortices of these bones are optimized in quasi-isolation (the conventional view) versus in the context of load sharing along the calcaneal shaft by "tension members" (the plantar ligament and superficial digital flexor tendon). This load-sharing concept replaces the conventional view, as we have argued in a recent publication that employs an advanced analytical model of habitual loading and fracture risk factors of the deer calcaneus. Like deer and sheep calcanei, many mammalian limb bones also experience prevalent bending, which seems problematic because the bone is weaker and less fatigue-resistant in tension than compression. To understand how bones adapt to bending loads and counteract deleterious consequences of tension, it is important to examine both strain-mode-specific (S-M-S) testing (compression testing of bone habitually loaded in compression; tension testing of bone habitually loaded in tension) and non-S-M-S testing. Mechanical testing was performed on individually machined specimens from the dorsal "compression cortex" and plantar "tension cortex" of adult deer calcanei and were independently tested to failure in one of these two strain modes. We hypothesized that the mechanical properties of each cortex region would be optimized for its habitual strain mode when these regions are considered independently. Consistent with this hypothesis, energy absorption parameters were approximately three times greater in S-M-S compression testing in the dorsal/compression cortex when compared to non-S-M-S tension testing of the dorsal cortex. However, inconsistent with this hypothesis, S-M-S tension testing of the plantar/tension cortex did not show greater energy absorption compared to non-S-M-S compression testing of the plantar cortex. When compared to the dorsal cortex, the plantar cortex only had a higher elastic modulus (in S-M-S testing of both regions). Therefore, the greater strength and capacity for energy absorption of the dorsal cortex might "protect" the weaker plantar cortex during functional loading. However, this conventional interpretation (i.e., considering adaptation of each cortex in isolation) is rejected when critically considering the load-sharing influences of the ligament and tendon that course along the plantar cortex. This important finding/interpretation has general implications for a better understanding of how other similarly loaded bones achieve anatomical optimization and functional adaptation.

Roles of collagen cross-links and osteon collagen/lamellar morphotypes in equine third metacarpals in tension and compression tests.

Many bones experience bending, placing one side in net compression and the other in net tension. Because bone mechanical properties are relatively reduced in tension compared with compression, adaptations are needed to reduce fracture risk. Several toughening mechanisms exist in bone, yet little is known of the influences of secondary osteon collagen/lamellar 'morphotypes' and potential interplay with intermolecular collagen cross-links (CCLs) in prevalent/predominant tension- and compression-loaded regions. Paired third metacarpals (MC3s) from 10 adult horses were prepared for mechanical testing. From one MC3/pair, 5 mm cubes were tested in compression at several mid-shaft locations. From contralateral bones, dumbbell-shaped specimens were tested in tension. Hence, habitual/natural tension- and compression-loaded regions were tested in both modes. Data included: elastic modulus, yield and ultimate strength, and energy absorption (toughness). Fragments of tested specimens were examined for predominant collagen fiber orientation (CFO; representing osteonal and non-osteonal bone), osteon morphotype score (MTS, representing osteonal CFO), mineralization, porosity and other histological characteristics. As a consequence of insufficient material from tension-tested specimens, CCLs were only examined in compression-tested specimens (HP, hydroxylysylpyridinoline; LP, lysylpyridinoline; PE, pentosidine). Among CCLs, only LP and HP/LP correlated significantly with mechanical parameters: LP with energy absorption, HP/LP with elastic modulus (both r=0.4). HP/LP showed a trend with energy absorption (r=-0.3, P=0.08). HP/LP more strongly correlated with osteon density and mineralization than CFO or MTS. Predominant CFO more strongly correlated with energy absorption than MTS in both testing modes. In general, CFO was found to be relatively prominent in affecting regional toughness in these equine MC3s in compression and tension.

Exploration of the synergistic role of cortical thickness asymmetry ("Trabecular Eccentricity" concept) in reducing fracture risk in the human femoral neck and a control bone (Artiodactyl Calcaneus).

The mechanobiology of the human femoral neck is a focus of research for many reasons including studies that aim to curb age-related bone loss that contributes to a near-exponential rate of hip fractures. Many believe that the femoral neck is often loaded in rather simple bending, which causes net tension stress in the upper (superior) femoral neck and net compression stress in its inferior aspect ("T/C paradigm"). This T/C loading regime lacks in vivo proof. The "C/C paradigm" is a plausible alternative simplified load history that is characterized by a gradient of net compression across the entire femoral neck; action of the gluteus medius and external rotators of the hip are important in this context. It is unclear which paradigm is at play in natural loading due to lack of in vivo bone strain data and deficiencies in understanding mechanisms and manifestations of bone adaptation in tension vs. compression. For these reasons, studies of the femoral neck would benefit from being compared to a 'control bone' that has been proven, by strain data, to be habitually loaded in bending. The artiodactyl (sheep and deer) calcaneus model has been shown to be a very suitable control in this context. However, the application of this control in understanding the load history of the femoral neck has only been attempted in two prior studies, which did not examine the interplay between cortical and trabecular bone, or potential load-sharing influences of tendons and ligaments. Our first goal is to compare fracture risk factors of the femoral neck in both paradigms. Our second goal is to compare and contrast the deer calcaneus to the human femoral neck in terms of fracture risk factors in the T/C paradigm (the C/C paradigm is not applicable in the artiodactyl calcaneus due to its highly constrained loading). Our third goal explores interplay between dorsal/compression and plantar/tension regions of the deer calcaneus and the load-sharing roles of a nearby ligament and tendon, with insights for translation to the femoral neck. These goals were achieved by employing the analytical model of Fox and Keaveny (J. Theoretical Biology 2001, 2003) that estimates fracture risk factors of the femoral neck. This model focuses on biomechanical advantages of the asymmetric distribution of cortical bone in the direction of habitual loading. The cortical thickness asymmetry of the femoral neck (thin superior cortex, thick inferior cortex) reflects the superior-inferior placement of trabecular bone (i.e., "trabecular eccentricity," TE). TE helps the femoral neck adapt to typical stresses and strains through load-sharing between superior and inferior cortices. Our goals were evaluated in the context of TE. Results showed the C/C paradigm has lower risk factors for the superior cortex and for the overall femoral neck, which is clinically relevant. TE analyses of the deer calcaneus revealed important synergism in load-sharing between the plantar/tension cortex and adjacent ligament/tendon, which challenges conventional understanding of how this control bone achieves functional adaptation. Comparisons with the control bone also exposed important deficiencies in current understanding of human femoral neck loading and its potential histocompositional adaptations.

Sea Urchin Spine Embedded in the Sole of the Foot: Eight-Year Radiographic Follow-Up Without Removal.

When sea urchin puncture injuries occur during coastal recreation or work activities, they often affect extremities, such as hands and feet. There is a plethora of information on treatments for these puncture injuries, with the most common among medical professionals being the removal of all partially embedded spines and the removal of as many fully embedded spines as possible. When the spines are deeply embedded and/or fragmented, they might not be removed, especially when they are not located in critical areas such as tendons or joints. This reflects the generally held notion that smaller spines and spine fragments will eventually dissolve or be absorbed. Here we report an unusual case where the tip of a sea urchin spine became embedded in the soft tissue of the sole of the foot of a 21-year-old male after he stepped on one after falling off a kayak off the coast of Oahu, Hawai'i. The deeply embedded spine was not removed. By three weeks after the injury, the patient did not have any symptoms, and eight years later, he was still symptom-free. Radiographs taken one year after the injury showed that the spine had fragmented into two pieces. The smaller piece was about 15% of the size of the original embedded spine, and it had apparently been absorbed (it was not seen on final radiographs eight years later). Analysis of radiographs eight years after the injury showed that the main or large spine fragment was still distinctly detectable in the soft tissue; there was no visible evidence that it had undergone significant absorption or migrated from the original location. The absence of any obvious radiographic rarefaction over eight years is contrary to the lore that sea urchin spines that remain in human soft tissue will exhibit significant, or complete, absorption or dissolution over months to a few years.

Schaalia (Formerly Actinomyces) turicensis Infection Following Open Rotator Cuff Repair.

We report the case of a male in his early 70s who developed a deep infection after an open rotator cuff repair, with Schaalia turicensis as the only organism isolated from a surgical biopsy of the tendon remnants and phlegmatic/purulent material at the failed repair site. This species was originally within the genus Actinomyces. We report this case because it is the only one that we could locate where an infected open rotator cuff repair site grew S. turicensis. Our patient was not diabetic, did not smoke, and did not have other recent or concurrent infections. He had hypertension, hypothyroidism, depression, and a hyperactive bladder. Hence, he only had minor risk factors for infection. His postoperative shoulder infection was eradicated with surgical irrigation and debridement, and 6.5 weeks of primarily oral antibiotic treatment. We also review the literature on infections after any shoulder surgery where Schaalia or Actinomyces species were isolated.

Osteomyelitis with abscess associated with acute closed upper humerus fracture in an adult: A case report.

A 64-year-old female presented with malaise and fever 11 days after a closed, minimally displaced humerus surgical neck fracture. MR imaging revealed an abscess around the fracture, which is a very rare occurrence in adults. Two open debridements and IV antibiotics eradicated the infection. Reverse total shoulder arthroplasty was eventually performed for fracture nonunion.

Septic Olecranon Bursitis With Osteomyelitis Attributed to Cutibacterium acnes: Case Report and Literature Overview of the Dilemma of Potential Contaminants and False-Positives.

We report an unusual case of acute septic olecranon bursitis, with probable olecranon osteomyelitis, where the only organism isolated in culture was initially considered a contaminant, Cutibacterium acnes. However, we ultimately considered it the likely causal organism when treatment for most of the other more likely organisms failed. This typically indolent organism is prevalent in pilosebaceous glands, which are scarce in the posterior elbow region. This case illustrates the often challenging empirical management of a musculoskeletal infection when the only organism isolated might be a contaminant, but successful eradication requires continued treatment as if it is the causal organism. The patient is a Caucasian 53-year-old male who presented to our clinic with a second episode of septic bursitis at the same location. Four years prior, he had septic olecranon bursitis from methicillin-sensitive Staphylococcus aureus that was treated uneventfully with one surgical debridement and a one-week course of antibiotics. In the current episode reported here, he sustained a minor abrasion. Cultures were obtained five separate times because of no growth and difficulty eradicating the infection. One culture grew C. acnes on day 21 of incubation; this long duration has been reported. The first several weeks of antibiotic treatment failed to eradicate the infection, which we ultimately attributed to inadequate treatment of C. acnes osteomyelitis. Although C. acnes has a well-known propensity for false-positive cultures as typically reported in post-operative shoulder infections, treatment for our patient's olecranon bursitis/osteomyelitis was successful only after several surgical debridements and a prolonged course of intravenous and oral antibiotics that targeted it as the presumptive causal organism. However, it was possible that C. acnes was a contaminant/superinfection, and another organism was the culprit, such as a Streptococcus or Mycobacterium species that was eradicated by the treatment regime targeted for C. acnes.

Acute Sternoclavicular Joint Sepsis With Medial Clavicle Osteomyelitis (Staphylococcus aureus) and Cervical-Thoracic Epidural Phlegmon in an Adult Female With No Apparent Risk Factors.

This is a case of a 71-year-old female with a history of only one known medical problem (hypertension) who presented with a right sternoclavicular joint (SCJ) infection in addition to (1) a contiguous lower cervical and upper thoracic epidural phlegmon and (2) cellulitis and a phlegmon in her posterior neck, which was subcutaneous and near the lower cervical and upper thoracic spinous processes. These loci of infection developed several days after she had pricked her fingers when cutting rose bushes and were initially considered to be epidural abscesses. However, after the patient was transferred to our tertiary medical center, a neurosurgeon and radiologist determined that the cervicothoracic infections were phlegmons rather than fully developed abscesses. The phlegmons were treated with only IV antibiotics. The SCJ infection was surgically debrided, and the medial clavicle was excised. Bone and fluid cultures grew methicillin-sensitive Staphylococcus aureus (S. aureus). The patient recovered uneventfully (the final follow-up was four years later). This case is uncommon because of the concurrent SCJ infection with medial clavicle osteomyelitis, cervical-thoracic epidural, and paraspinous phlegmons.

Octogenarian With Acromion Stress Fracture Nonunion With Reverse Total Shoulder Prosthesis Reconstructed With Plates and Screws: A Case Report.

An 85-year-old male underwent open reduction and internal fixation (ORIF) for a displaced acromion stress fracture that occurred two years prior. The complete fracture occurred two months after an ipsilateral reverse total shoulder arthroplasty (RTSA). Four weeks after his RTSA, the pain was felt at the posterior-superior shoulder with activities of his daily living as a rancher, reflecting non-compliant use. A stress fracture was suspected but not detected radiographically. Four weeks later, higher pain occurred after he lifted a hay bale, and a displaced basilar acromion fracture was detected. Non-operative management spanned 20 months, which he ultimately deemed unacceptable because of pain with minor activities. ORIF was then done. Approximately 10 months after the ORIF surgery, both plates sustained fatigue breakage; however, the fracture consolidated, and his pain remained low. He is the oldest patient described to ultimately have a successful acromion fracture ORIF and only the third reported acromion fracture ORIF in octogenarians following RTSA. We report the ORIF technique, its good outcome, and a literature review of elderly patients who had ORIF for this problem.

Presumed Glenoid SLAP Tear in an Adolescent Football Player Belied the Presence of a Coracoid Growth Plate Fracture: A Diagnostic Conundrum.

We report the case of a 13-year-old male who sustained a right shoulder injury while playing quarterback in an American football game. A noncontrast MRI scan showed evidence of a possible grade 1 SLAP tear (SLAP = superior labral anterior-posterior), and surgery was recommended. However, at the preoperative visit, the surgeon was suspicious that the main source of pain had been missed. Bilateral shoulder radiographs taken for comparative analysis revealed a Salter-Harris type I coracoid growth-plate fracture. Therefore, the surgeon planned to manage the patient nonoperatively and postponed the proposed SLAP tear surgery. The patient was instructed to cease participation in athletic events and undergo physical therapy. Hoping to expedite his healing with platelet or stem cell injections, the parents sought an opinion from another physician who obtained a right shoulder MRI with intra-articular contrast. This confirmed that there was no SLAP tear. We concluded that the patient initially had glenohumeral and coracoclavicular ligament strains and a coracoid growth-plate fracture. The SLAP tear suggested by the initial MRI proved to be a red herring, belying an accurate diagnosis. The patient ultimately recovered fully with physical therapy and without surgery or other interventions.

Acute compartment syndrome of the contralateral thigh following reconstructive shoulder surgery done for multidirectional shoulder instability in lateral decubitus position.

A man in his early 40s had revision reconstructive surgery on his left shoulder while in a right lateral decubitus position. The prolonged surgery (7 hours) caused acute compartment syndrome (ACS) in the contralateral (right) thigh. Moderate pain and swelling of the contralateral thigh ('well limb') was first noted in the recovery room. After progression to severe swelling and numbness in his right toes, fasciotomies of the right thigh were performed, confirming ACS. Thirteen months later he returned to his prior work without lower extremity discomfort or limitations, and he reported a good result from the revision shoulder surgery. Non-traumatic ACS of a well limb is a rare complication of surgery performed in the lateral decubitus position. We suggest that moving the patient temporarily, or to a new position (eg, beach chair), should be considered when the duration of surgery approaches 4.5 hours.

Manual wheelchair use leads to a series of failed shoulder replacements: A case report and literature review.

Manual wheelchair users place high stress on their shoulders. We describe a 69-year-old male who developed end-stage shoulder osteoarthritis from chronic manual wheelchair (MW) use. Three prosthetic total shoulder replacements failed, reflecting his refusal to transition to an electric wheelchair. MW use must be avoided in some of these patients.

Priorities for improvement across cancer and non-cancer related preventive services among rural and non-rural clinicians.

INTRODUCTION: It is not realistic for most clinicians to perform the multitude of recommended preventive primary care services. This is especially true in low resource and rural settings, creating challenges to delivering high-quality care. This study collected stakeholder input from clinicians on which services they most need to improve. METHODS: The authors conducted a survey of primary care physicians 9-12/2021, with an emphasis on rural practices, to assess areas in which clinicians felt the greatest needs for improvement. The survey focused on primary prevention (behavior change counseling) and cancer screening, and contrasted needs for improvement for these services vs. other types of screening, and between clinicians in rural vs. non-rural practices. RESULTS: There were 326 respondents from 4 different practice-based research networks, a wide range of practice types, 49 states and included 177 clinicians in rural settings. Respondents rated the need to improve delivery of primary prevention counseling services highest, with needs for nutrition and dietary assessment and counseling rated highest followed by physical activity and with almost no differences between rural and nonrural. Needs for improvement in cancer screenings were rated higher than non-cancer screenings, except for blood pressure screening. CONCLUSIONS: Both rural and nonrural primary care clinicians feel a need for improvement, especially with primary prevention activities. Although future research is needed to replicate these findings with different populations and other types of preventive service activities, greater priority should be given to development of practical, stakeholder informed assistance and resources for primary care to conduct primary prevention.