Clinical and radiographic outcomes after total hip arthroplasty with the NANOS neck preserving hip stem: a 10 to 16-year follow-up study

Background Short-stem Hip Arthroplasty (SHA) are increasingly implanted in recent years thanks to their potential advantage in preserving metaphyseal bone-stock. Among them, the NANOS® short-stem implant demonstrated satisfactory results to short and mid-term. The purpose of this retrospective study was to evaluate the clinical and radiographic outcome of the Nanos® short stem at a minimum follow-up of 10 years. Methods Sixty-seven patients aged 53 ± 20 years were enlisted in the study, for a total of 72 hips. Primary outcomes were survivorship of the implant and clinical outcome measured using the Hip disability and Osteoarthritis Outcome scores (HOOS) and the Short Form Survey (SF12) questionnaire. The secondary outcome was a radiological evaluation calculating the inclination and the anteversion angle of the acetabular cup for each implant and investigating osteolysis, heterotopic ossifications and stem position. Results We observed a 95.5% stem survivorship. The complication rate was 7.6% and three implants underwent revision because of an aseptic loosening, an infection and a periprosthetic fracture due to trauma. Among 58 patients (63 hips) evaluated in an outpatient visit 10–16 years after surgery, improvement in clinically relevant scores comparing with baseline was observed: HOOS score increased after surgery in all its subcategories (from 32.25 ± 14.07% up to 91.91 ± 9.13%) as well as SF12 which increased by more than 18 percentage points. On clinical assessment, the range of motion (ROM) was restored at follow-up, 1 patient (1.7%) showed a squeaking hip and 2 (3.4%) reported leg-length discrepancy. Neutral stem positioning was achieved in 58 hips and heterotopic ossifications occurred in 10 hips (16%). Conclusions The current study reports good clinical and radiological outcomes following NANOS® short-stem hip implant at minimum 10 years-follow-up. Since the high rate of stem survivorship, the low complication rate demonstrated and the overall patient satisfaction, our results suggest NANOS® neck-preserving prostheses should be considered as a valid alternative to standard implants.

Extensive Heterotopic Ossification of Bilateral Hip and Knee Joints in a Patient with Recurrent Traumatic Injuries

Background: Heterotopic ossification (HO) refers to the growth of lamellar bone in soft tissues. Extensive heterotopic ossification is rarely seen. In this case, we illustrate a 35-year-old civilian patient with extensive HO due to recurrent traumatic injuries with no neurological deficit. Case Presentation: A 35-year-old man, with a history of recurrent trauma episodes in the past year, presented with pain and swellings in bilateral lower limbs. Physical examination showed stiffness and deformities of bilateral hip and knee joints. Plain x-ray showed patchy ossification extending from hip joints to knee joints bilaterally. 3-dimensional Computer Tomography (3D-CT) showed extensive heterotopic ossifications along gluteal muscles, quadratus muscles and the deep fascia beneath, confirming the diagnosis of extensive heterotopic ossifications of bilateral hip and knee joints. Excision of ossified tissues and re-mobilization of iliotibial bands were performed. Early recovery after surgery (ERAS) strategy was used to speed up recovery. Conclusion: i) Extensive heterotopic ossification in civilian patients is possible. Clinical history should be reviewed to rule out recurrent traumatic injury. Surgery should be considered. ii) Three-dimensional Computer Tomography (3D-CT) is a viable tool for surgical planning to show the extent, site, and anatomical relationship with adjacent tissues. iii) Post-op early recovery after surgery (ERAS) should be considered for better clinical outcomes.

Neurogenic Heterotopic Ossifications Recapitulate Hematopoietic Stem Cell Niche Development Within an Adult Osteogenic Muscle Environment

Hematopoiesis and bone interact in various developmental and pathological processes. Neurogenic heterotopic ossifications (NHO) are the formation of ectopic hematopoietic bones in peri-articular muscles that develop following severe lesions of the central nervous system such as traumatic cerebral or spinal injuries or strokes. This review will focus on the hematopoietic facet of NHO. The characterization of NHO demonstrates the presence of hematopoietic marrow in which quiescent hematopoietic stem cells (HSC) are maintained by a functional stromal microenvironment, thus documenting that NHOs are neo-formed ectopic HSC niches. Similarly to adult bone marrow, the NHO permissive environment supports HSC maintenance, proliferation and differentiation through bidirectional signaling with mesenchymal stromal cells and endothelial cells, involving cell adhesion molecules, membrane-bound growth factors, hormones, and secreted matrix proteins. The participation of the nervous system, macrophages and inflammatory cytokines including oncostatin M and transforming growth factor (TGF)-β in this process, reveals how neural circuitry fine-tunes the inflammatory response to generate hematopoietic bones in injured muscles. The localization of NHOs in the peri-articular muscle environment also suggests a role of muscle mesenchymal cells and bone metabolism in development of hematopoiesis in adults. Little is known about the establishment of bone marrow niches and the regulation of HSC cycling during fetal development. Similarities between NHO and development of fetal bones make NHOs an interesting model to study the establishment of bone marrow hematopoiesis during development. Conversely, identification of stage-specific factors that specify HSC developmental state during fetal bone development will give more mechanistic insights into NHO.

Etoricoxib is safe and effective in preventing heterotopic ossification after primary total hip arthroplasty

Background Heterotopic ossifications are a common complication after total hip arthroplasty. Low-dose radiation therapy and non-steroidal anti-inflammatory drugs have proven to effectively reduce the rate of heterotopic ossification after total hip arthroplasty. However, a low number of studies describe an equal efficiency of etoricoxib. This work shows first results on the examination of a larger group with 194 subjects to analyze efficiency and rate of side effects under treatment with etoricoxib. Methods Clinical examinations were performed the day before surgery and after at least 12 months. The survey of clinical and functional outcome was done with Harris Hip Score (HHS). Conventional antero-posterior radiographs and second plane in frog leg position were assessed. Results In total, 14 undesirable side effects (7.4%) and only four early terminations of therapy (2.1%) were documented. A complete 1-year follow-up examination including radiographs could be done in 143 subjects (79.4%). Only 28 subjects (19.6%) developed heterotopic ossifications from which 92.9% were classified in type 1 and 7.1% in type 2 using the method described by Brooker. The results do not show correlations with body mass index, extended treatment (more than ten days), or clinical and functional outcome (measured by “Harris Hip Score”). However, male subjects show a significantly higher rate of heterotopic ossifications. Conclusions The investigations presented in this study confirm a good efficiency of etoricoxib for the prevention of heterotopic ossifications in comparison with classical methods such as radiation or drug therapy and show a low rate of undesirable side effects.

Cardiopulmonary and Neurologic Dysfunctions in Fibrodysplasia Ossificans Progressiva

Fibrodysplasia Ossificans Progressiva (FOP) is an ultra-rare but debilitating disorder characterized by spontaneous, progressive, and irreversible heterotopic ossifications (HO) at extraskeletal sites. FOP is caused by gain-of-function mutations in the Activin receptor Ia/Activin-like kinase 2 gene (Acvr1/Alk2), with increased receptor sensitivity to bone morphogenetic proteins (BMPs) and a neoceptor response to Activin A. There is extensive literature on the skeletal phenotypes in FOP, but a much more limited understanding of non-skeletal manifestations of this disease. Emerging evidence reveals important cardiopulmonary and neurologic dysfunctions in FOP including thoracic insufficiency syndrome, pulmonary hypertension, conduction abnormalities, neuropathic pain, and demyelination of the central nervous system (CNS). Here, we review the recent research and discuss unanswered questions regarding the cardiopulmonary and neurologic phenotypes in FOP.

Severe Heterotopic Ossification with Proximal Entrapment of the Ulnar Nerve following Primary Anterior Shoulder Dislocation

Heterotopic ossifications (HO) in the shoulder are rare. The effectiveness of conservative treatment is limited, and therefore, symptomatic cases are usually treated surgically. However, there are no guidelines for the surgical treatment of HO. Herein, we report the case of a 45-year-old man with severe HO and proximal entrapment of the ulnar nerve following primary anterior shoulder dislocation without concomitant injuries (e.g., fracture and rotator cuff tears). Surgical intervention was indicated, including resection of HO and neurolysis of the brachial plexus. Nine months after surgery, the patient presented with restored shoulder function, pain relief, and good patient satisfaction. The case shows that the ulnar nerve can also be impaired due to HO following shoulder dislocation.

Pronounced Heterotopic Ossifications after Traumatic Hamstring Rupture: Is an Ossification Prophylaxis Useful?

Hamstring injuries include a wide range of injuries and affect mainly athletes with high eccentric loads (football, athletics, rugby, climbing). According to the latest literature, unrecognized traumatic ruptures can cause permanent discomfort and may be associated with a poorer postoperative outcome when delayed surgical therapy is performed. Heterotopic ossifications (HO) after hamstring rupture have been described in individual case reports and smaller studies so far. Heterotopic ossifications are mainly known in hip surgery and elbow fractures. In this case report, a 48-year-old patient presented with an increasing swelling with hardening in the area of the right ischial tuberosity. One year before, an impact trauma was the reason for a traumatic hamstring rupture which was diagnosed with a delay. The HO was excised and the tendon refixed with two suture anchors. By limiting the range of motion with a hip-knee orthosis for 9 weeks, a regular postoperative healing process was observed. Heterotopic ossifications after hamstring ruptures have been reported repeatedly but have not been evaluated in any major study so far. It should therefore be considered whether prophylaxis with NSAIDs should be used for conservatively and surgically treated hamstring ruptures, analogous to the ossification prophylaxis for hip endoprostheses or fractures in the elbow region.

Osteosarcoma of talus with heterotopic ossifications and lung metastases

Osteosarcoma is the most common malignant bone tumor and is known to occur mainly in the metaphyses of long bones. However, a few cases of osteosarcoma in talus have been reported in older patients. We experienced an osteosarcoma of an 80-year-old male patient with a talus which is rarely reported and evaluated disease patterns with four different imaging modalities.