Inertial measurement units to evaluate the efficacity of Equino Varus Foot surgery in post stroke hemiparetic patients: a feasibility study.

INTRODUCTION: This study evaluates the gait analysis obtained by Inetial Measurement Units (IMU) before and after surgical management of Spastic Equino Varus Foot (SEVF) in hemiplegic post-stroke patients and to compare it with the functional results obtained in a monocentric prospective cohort. METHODS: Patients with post-stroke SEVF, who underwent surgery in a single hospital between November 2019 and December 2021 were included. The follow-up duration was 6 months and included a functional analysis using Goal Attainment Scaling (GAS) and a Gait analysis using an innovative Multidimensional Gait Evaluation using IMU: the semiogram. RESULTS: 20 patients had a gait analysis preoperatively and at 6 months postoperatively. 90% (18/20) patients had a functional improvement (GAS T score ≥ 50) and 50% (10/20) had an improvement in walking technique as evidenced by the cessation of the use of a walking aid (WA). In patients with functional improvement and modification of WA the change in the semiogram area was + 9.5%, sd = 27.5%, and it was + 15.4%, sd = 28%. In the group with functional improvement without change of WA. For the 3 experiences (two patients) with unfavorable results, the area under the curve changed by + 2.3%, -10.2% and - 9.5%. The measurement of the semiogram area weighted by average speed demonstrated very good reproducibility (ICC(1, 3) = 0.80). DISCUSSION: IMUs appear to be a promising solution for the assessment of post-stroke hemiplegic patients who have undergone SEVF surgery. They can provide a quantified, objective, reliable in individual longitudinal follow up automated gait analysis solution for routine clinical use. Combined with a functional scale such as the GAS, they can provide a global analysis of the effect of surgery.

International Recommendations to Manage Poststroke Equinovarus Foot Deformity Validated by a Panel of Experts Using Delphi.

OBJECTIVE: To establish international recommendations for the management of spastic equinovarus foot deformity. DESIGN: Delphi method. SETTING: International study. PARTICIPANTS: A total of 24 international experts (N=24) in neuro-orthopedic deformities, from different specialties (Physical and Rehabilitation Medicine physicians, neurologists, geriatricians, orthopedic surgeons, neurosurgeons, plastic surgeons). INTERVENTIONS: Experts answered 3 rounds of questions related to important aspects of diagnosis, assessment, and treatment of spastic equinovarus foot deformity. MAIN OUTCOME MEASURES: A consensus was established when at least 80% of experts agreed on a statement RESULTS: A total of 52 items reached consensus. Experts recommend assessing effect of the deformity on functional activities before treatment. Before treatment, it is crucial to differentiate spastic muscle overactivity from soft tissue contractures, identify which muscles are involved in the deformity, and evaluate the activity of antagonist muscles. Motor nerve blocks, 2-dimensional video analysis, and radiologic examinations are often required to complement a clinical examination. The treatment of equinovarus foot depends on the correctability of the deformity and the patient's ability to stand or walk. The preoperative assessment should include an interdisciplinary consultation that must finalize a formal agreement between physicians and the patient, which will define personalized attainable goals before surgery. CONCLUSION: The establishment of guidelines on managing equinovarus foot will help physicians and surgeons, specialists, and nonspecialists to diagnoses and assess the deformity and direct patients to a network of experts to optimize patient functional recovery and improve their autonomy.

Neuro-Orthopedic Surgery for Equinovarus Foot Deformity in Adults: A Narrative Review.

Neuro-orthopedic surgery is an alternative to the conservative treatment of spastic equinovarus foot (SEF) in adults. The objective of the present narrative review was to summarize current practice with regard to patient assessment, the choice of treatment, the various neuro-orthopedic procedures, and the latter's outcomes. We searched literature databases (MEDLINE, EMBASE, Cochrane) for original articles or opinion papers on surgical treatment of spastic equinovarus foot in adults. Neuro-orthopedic approaches require a careful analysis of the patient's and/or his/her caregiver needs and thus relevant treatment goals. Surgical planning requires detailed knowledge of impairments involved in the spastic equinovarus foot deformity based on a careful clinical examination and additional information from diagnostic nerve blocks and/or a quantitative gait analysis. Procedures mainly target nerves (neurotomy) and tendons (lengthening, transfer, tenotomy). These procedures reduce impairments (spasticity, range of motion, and foot position), improve gait and walking function, but their impact on participation and personalized treatment goals remains to be demonstrated. Neuro-orthopedic surgery is an effective treatment option for spastic equinovarus foot in adults. However, practice is still very heterogeneous and there is no consensus on the medical strategies to be applied before, during and after surgery (particularly the type of anesthesia, the need for immobilization, rehabilitation procedures).

Efficacy of colistin alone and in various combinations for the treatment of experimental osteomyelitis due to carbapenemase-producing Klebsiella pneumoniae.

OBJECTIVES: In a new experimental model of carbapenemase-producing Klebsiella pneumoniae osteomyelitis we evaluated the efficacy of colistin alone and in various combinations and examined the emergence of colistin-resistant strains and cross-resistance to host defence peptides (HDPs). METHODS: KPC-99YC is a clinical strain with intermediate susceptibility to meropenem (MIC = 4 mg/L) and full susceptibility to gentamicin, colistin and tigecycline (MICs = 1 mg/L) and fosfomycin (MIC = 32 mg/L). Time-kill curves were performed at 4× MIC. Osteomyelitis was induced in rabbits by tibial injection of 2 × 108 cfu. Treatment started 14 days later for 7 days in seven groups: (i) control; (ii) colistin; (iii) colistin + gentamicin; (iv) colistin + tigecycline; (v) colistin + meropenem; (vi) colistin + meropenem + gentamicin; and (vii) colistin + fosfomycin. RESULTS: In vitro, colistin was rapidly bactericidal, but regrowth occurred after 9 h. Combinations of colistin with meropenem or fosfomycin were synergistic, whereas combination with tigecycline was antagonistic. In vivo, colistin alone was not effective. Combinations of colistin with meropenem or fosfomycin were bactericidal (P < 0.001) and the addition of gentamicin enhanced the efficacy of colistin + meropenem (P = 0.025). Tigecycline reduced the efficacy of colistin (P = 0.007). Colistin-resistant strains emerged in all groups except colistin + fosfomycin and two strains showed cross-resistance to HDP LL-37. CONCLUSIONS: In this model, combinations of colistin plus meropenem, with or without gentamicin, or colistin plus fosfomycin were the only effective therapies. The combination of colistin and tigecycline should be administered with caution, as it may be antagonistic in vitro and in vivo.

Soft Tissue Surgery for Adults With Nonfunctional, Spastic Hands Following Central Nervous System Lesions: A Retrospective Study.

PURPOSE: Soft tissue surgery for upper extremity contractures can improve hygiene, pain, and appearance in adults with central nervous system lesions. The goal of such interventions is highly individual; thus, goal attainment scaling (GAS; a method of scoring the extent to which patient's individual goals are achieved [5 levels] in the course of intervention and using T score values) is pertinent to evaluate outcome. The objective of this study was to assess the effect of soft tissue surgery for upper extremity muscle contractures in patients with central nervous system lesions using GAS. METHODS: Retrospective data from 70 interventions were included (63 patients; 23 women). The mean age was 51.3 ± 16.2 years (range, 24.2-87.0 years). The primary goal was to improve hygiene (n = 58), pain (n = 10), or appearance (n = 2). The etiologies were stroke (n = 35), traumatic brain injury (n = 16), cerebral anoxia (n = 4), neurodegenerative disease (n = 6), and cerebral palsy (n = 2). The GAS score was calculated before surgery and 3 months after surgery. RESULTS: The T score (which took into account the weight of each goal) was 52.3 at 3 months (38.5 before surgery), corresponding to a "better than expected" outcome. The mean of the differences of the GAS score for each goal before and after surgery increased by 1.27 for hygiene, 1.06 for pain, and 1.00 for appearance. CONCLUSIONS: Soft tissue surgery can safely and effectively improve hygiene, pain, and appearance in adults with cerebral damage. The preoperative evaluation should be multidisciplinary. The GAS is a useful tool to assess the effectiveness of orthopedic surgery for these patients. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Osteonecrosis of the Femoral Head: A Proposed New Treatment in Homozygous Sickle Cell Disease.

UNLABELLED: Possibilities for bone reconstruction in osteonecrosis of the femoral head in sickle cell hemoglobinopathies before the end of growth have not been assessed. The aim of our study was to evaluate the morphological and functional results in 11 osteonecrosis of the femoral head because of homozygous sickle cell disease. Surgical treatment consisted of a triple acetabular osteotomy in seven cases, femoral varus osteotomy in two cases and a combination of both in two cases. The severity of the osteonecrosis was evaluated on radiographs and magnetic resonance imaging (MRI), pre- and postoperative, and function of the hip joint was assessed by Harris and Postel Merle d'Aubigné scores. The anesthetic part (pre- and postoperative) and eventual complications were collected and analyzed. The maximum follow-up was between 1 to 9.6 years. All patients were considered to be satisfactory at maximum follow-up. The severity of the initial damage was not associated with any morphological or functional outcome at maximum follow-up. All patients had an objective functional gain. We found no general complications. We proposed a decision tree for the patient's management of avascular necrosis of the femoral head in sickle cell hemoglobinopathies before bone maturity, and with an Arlet and Ficat's stage of 3 or 4. The results of this study confirmed the interest of conservative surgical treatment in children with homozygous sickle cell anemia in case of osteonecrosis of the femoral head. LEVEL OF EVIDENCE: IV (cases series of our department).

Pharmacokinetic variability of clindamycin and influence of rifampicin on clindamycin concentration in patients with bone and joint infections.

PURPOSE: Clindamycin, a lincosamide antibiotic with a good penetration into bone, is widely used for treating bone and joint infections by Gram-positive pathogens. To be active against Staphylococcus spp, its concentration at the infection site, C, must be higher than 2× the minimal inhibitory concentration (MIC). The aims of the work were to study the determinants of plasma clindamycin trough concentration, C min, especially the effect of co-treatment with rifampicin, and the consequences on clinical outcome. METHODS: An observational study was performed, involving patients hospitalized for a bone and joint infection who received clindamycin as part of their antibiotic treatment. Target C min was 1.7 mg/L, to reach the desired bone concentration/MIC >2, assuming a 30% diffusion into bone and MIC = 2.5 mg/L. RESULTS: Sixty one patients (mean age: 56.8 years, 57.4% male) were included between 2007 and 2011. 72.1% underwent a surgery on a foreign material, and 91.1% were infected by at least a Gram-positive micro-organism. Median C min value was 1.39 mg/L, with 58% of the values below the threshold value of 1.7 mg/L. Median C min was significantly lower for patients taking rifampicin (0.46 vs 1.52 mg/L, p = 0.034). No patient with rifampicin co-administration reached the target concentration (maximal C min: 0.85 mg/L). After a median follow-up of 17 months (1.5-38 months), 4 patients relapsed, 2 died and 47 (88.7% of the patients with known outcome) were cured, independently of association with rifampicin. CONCLUSIONS: This study shows the high inter-variability of plasma clindamycin concentration and confirms that co-treatment with rifampicin significantly decreases clindamycin trough concentrations.

Ceftaroline-Fosamil efficacy against methicillin-resistant Staphylococcus aureus in a rabbit prosthetic joint infection model.

Ceftaroline (CPT), the active metabolite of the prodrug ceftaroline-fosamil (CPT-F), demonstrates in vitro bactericidal activity against methicillin-resistant Staphylococcus aureus (MRSA) and is effective in rabbit models of difficult-to-treat MRSA endocarditis and acute osteomyelitis. However, its in vivo efficacy in a prosthetic joint infection (PJI) model is unknown. Using a MRSA-infected knee PJI model in rabbits, the efficacies of CPT-F or vancomycin (VAN) alone and combined with rifampin (RIF) were compared. After each partial knee replacement with a silicone implant that fit into the tibial intramedullary canal was performed, 5 × 10(7) MRSA CFU (MICs of 0.38, 0.006, and 1 mg/liter for CPT, RIF, and VAN, respectively) was injected into the knee. Infected animals were randomly assigned to receive no treatment (controls) or CPT-F (60 mg/kg of body weight intramuscularly [i.m.]), VAN (60 mg/kg i.m.), CPT-F plus RIF (10 mg/kg i.m.), or VAN plus RIF starting 7 days postinoculation and lasting for 7 days. Surviving bacteria in crushed tibias were counted 3 days after ending treatment. Although the in vivo mean log10 CFU/g of CPT-treated (3.0 ± 0.9, n = 12) and VAN-treated (3.5 ± 1.1, n = 12) crushed bones was significantly lower than those of controls (5.6 ± 1.1, n = 14) (P < 0.001), neither treatment fully sterilized the bones (3/12 were sterile with each treatment). The mean log10 CFU/g values for the antibiotics in combination with RIF were 1.9 ± 0.5 (12/14 were sterile) for CPT-F and 1.9 ± 0.5 (12/14 were sterile) for VAN. In this MRSA PJI model, the efficacies of CPT-F and VAN did not differ; thus, CPT appears to be a promising antimicrobial agent for the treatment of MRSA PJIs.

Efficacy of ceftazidime-avibactam in various combinations for the treatment of experimental osteomyelitis due to Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae.

BACKGROUND: Optimal treatment of carbapenemase-producing Enterobacterales (CPE) bone infections is poorly defined. This study evaluated the efficacy of the novel beta-lactam-beta-lactamase inhibitor-ceftazidime-avibactam (CAZ-AVI)-with different antibiotic combinations in an experimental model of CPE osteomyelitis. METHODS: KPC-99YC is a clinical strain of Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae with intermediate susceptibility to meropenem (MIC 4 mg/L), gentamicin (MIC 0.25 mg/L), colistin (MIC 0.25 mg/L), fosfomycin (MIC 4 mg/L) and ceftazidime-avibactam (MIC 1 mg/L). Time-kill curves were performed at 4x MIC. Osteomyelitis was induced in rabbits by tibial injection of 2×108 CFU of KPC-99YC. Six groups started treatment 14 days later for 7 days: control, colistin, CAZ-AVI, CAZ-AVI plus gentamicin, CAZ-AVI plus colistin and CAZ-AVI plus fosfomycin. Antibiotic dosages were selected to simulate plasma concentrations obtained in humans. Treatment was evaluated according to bone cultures quantified in log10 CFU. RESULTS: In vitro, CAZ-AVI plus colistin or gentamicin were rapidly bactericidal in contrast with CAZ-AVI plus fosfomycin. In vivo, compared with controls, colistin alone (P = 0.045) and CAZ-AVI alone or in combination significantly lowered bone bacterial counts (P < 0.001). Bone sterilisation was achieved in 67% and 100% of animals with combinations of CAZ-AVI plus colistin or gentamicin (P = 0.001 and P < 0.001, respectively) whereas other treatments were no different from controls. CAZ-AVI plus gentamicin provided greater bone bacterial reduction than CAZ-AVI plus colistin (P = 0.033). No CAZ-AVI-resistant strains emerged in treated rabbits, regardless of combination. CONCLUSIONS: CAZ-AVI plus gentamicin was the best effective combination therapy. Combinations with CAZ-AVI appear to be a promising treatment of KPC-producing Klebsiella pneumoniae osteomyelitis.

Bacterial Lipopolysaccharides Exacerbate Neurogenic Heterotopic Ossification Development.

Neurogenic heterotopic ossifications (NHO) are heterotopic bones that develop in periarticular muscles after severe central nervous system (CNS) injuries. Several retrospective studies have shown that NHO prevalence is higher in patients who suffer concomitant infections. However, it is unclear whether these infections directly contribute to NHO development or reflect the immunodepression observed in patients with CNS injury. Using our mouse model of NHO induced by spinal cord injury (SCI) between vertebrae T11 to T13 , we demonstrate that lipopolysaccharides (LPS) from gram-negative bacteria exacerbate NHO development in a toll-like receptor-4 (TLR4)-dependent manner, signaling through the TIR-domain-containing adapter-inducing interferon-ß (TRIF/TICAM1) adaptor rather than the myeloid differentiation primary response-88 (MYD88) adaptor. We find that T11 to T13 SCI did not significantly alter intestinal integrity nor cause intestinal bacteria translocation or endotoxemia, suggesting that NHO development is not driven by endotoxins from the gut in this model of SCI-induced NHO. Relevant to the human pathology, LPS increased expression of osteoblast markers in cultures of human fibro-adipogenic progenitors isolated from muscles surrounding NHO biopsies. In a case-control retrospective study in patients with traumatic brain injuries, infections with gram-negative Pseudomonas species were significantly associated with NHO development. Together these data suggest a functional association between gram-negative bacterial infections and NHO development and highlights infection management as a key consideration to avoid NHO development in patients. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Functional and/or hygienic surgery of the hypertonic upper limb.

Neuro-orthopedic complications of the upper limb affect all of its joints and lead to a multitude of clinical pictures. The clinical assessment, which should be multidisciplinary, will have to answer basic questions to define the goal(s) and the appropriate surgical strategy. What is the patient's and family's complaint? What is the possible utility of the deformities? What is the type of deformity? Is it reducible or not? What is the contribution of the upper limb deformities versus that of any associated injuries to the discomfort? Several difficulties exist in the clinical assessment: evaluation of the antagonists especially the wrist extensor muscles; the intrinsic deformity component, which can be masked by the extrinsic component when retracted, the muscles responsible for a wrist flexion contracture and the complex shoulder deformities. Many patients have multiple deformities, which creates a problem for the hierarchy of corrections depending on the objectives. The answer to these questions helps to define a clear objective that will be formalized in a contract with the patient and subsequently to define the surgical strategy. Surgery is based on a simple principle: relax the muscles on the side of the deformity, either by selective neurotomy if there is a simple hypertonia, or by a tendon procedure if the muscle is retracted; compensate for the antagonists if they are deficient, and potentially stabilize the joint. Conservative procedures are preferred to preserve the possibility of functional recovery in the future. The wide range of medical and surgical solutions allows the patient's care to be personalized. In the upper limb, the results are better for hygienic, positioning, and analgesic objectives. They remain more difficult to obtain for functional objectives, due to the biomechanical complexity of gripping.

Early diagnosis of heterotopic ossification among patients admitted to a neurological Post-Intensive Care Rehabilitation Unit.

BACKGROUND: Heterotopic ossification (HO) is defined as the formation of endochondral bone within soft tissue. Non-genetic forms, mainly corresponding to a consequence of bone, brain or spinal cord injury, are the most common. HO leads to important functional limitations and alteration of quality of life. To our knowledge, the time between brain, bone, or spinal cord injury and clinical suspicion of HO has never been studied. By admitting patients with severe neurological disorders, we hypothesized that the prevalence of HO in neurological post-intensive care rehabilitation units (PICRU) might be significant as these patients have recognized risk factors for HO. AIM: This study aimed to investigate HO among patients admitted to a neurological PICRU with two objectives: 1) to describe the prevalence of HO in PICRU; 2) to assess the time between neurological disorder, clinical suspicion of HO and radiological diagnosis. DESIGN: A monocentric retrospective cohort study. SETTING: PICRU in our public university teaching hospital. This inpatient referral department is specifically dedicated to the early discharge from Intensive Care Units (ICU) of patients with severe neurological impairment who need rehabilitation. POPULATION: We study all patients admitted between April 2016 and January 2019. One hundred twenty-five subjects were admitted for a rehabilitation program after neuro-trauma or stroke. We included all first-time stays in PICRU lasting 7 days or longer. METHODS: Retrospective data extraction using administrative data from an electronic patient management program was done to select eligible subjects. Included subjects were then identified by a retrospective review of electronic inpatient medical records after patient discharge. Data of interest were collected from these same medical records. RESULTS: Forty-four HO were diagnosed in 24 subjects (24/125; 19%), with a median number of 2 [1; 2] HO per subject. Neurological trauma was the main reason for admission to ICU (89/125; 71%) and half of patients had a traumatic brain injury (TBI) (67/125; 54%). The diagnosis of HO was made in PICRU in 75% of cases. Clinical suspicion of HO (autonomic dysfunction, local inflammatory signs, pain, or reduced joint range of motion) was made 6 [5; 7] weeks after admission to ICU. Radiological confirmation of clinical suspicion or fortuitous diagnosis by imaging (50% of the cases) occurred 8 [7; 12] weeks after admission to ICU. The median time of clinical suspicion or radiological diagnosis was 1 week after admission to PICRU. CONCLUSIONS: HO is a sub-acute complication which develops in patients admitted to ICU for severe central nervous system disorders as clinical suspicion or radiological confirmation of diagnosis was made within the first week after admission in neurological PICRU (i.e. 6 to 8 weeks after ICU admission). CLINICAL REHABILITATION IMPACT: As treatment for HO may at least partially improves rehabilitation and quality of life, we recommend a systematic screening in PICRU patients for HO by clinical examination supplemented by imaging in case of suspicion.

Comparison of magnetic resonance imaging and computed tomography for bone assessment of neurogenic heterotopic ossification of the hip: a preliminary study.

BACKGROUND: Neurogenic heterotopic ossification (NHO) is a frequent complication, often involving the hip. The functional impact may require surgical management and pre-surgical imaging assessment is necessary, usually by computed tomography (CT). We aimed to compare the performances of magnetic resonance imaging (MRI) and CT for bone assessment on pre-surgical imaging of the heterotopic ossifications and their features in NHO of the hip. METHODS: This single-center prospective preliminary study included all patients who underwent surgery for NHO with joint limitation from July 2019 to March 2020. All patients had a CT after biphasic iodinated solution injection and an MRI including T1-weighted, STIR and ZTE sequences. Standardized reports were completed for both exams for each patient, evaluating location, implantation and fragmentation of NHO, relation to the joint capsule and bone mineralization, then were compared. RESULTS: Seven patients from 32 to 70 years old (mean = 50.2 ± 17.2 years) were evaluated. NHO were bilateral in 2 patients, for a total of nine hips: six right hips and three left hips. Observed concordance rates between MRI and CT were, respectively, 94.4% for location, 100% for circumferential extension, 87.3% for implantation 88.9% for fragmentation, 77.8% for relation to the joint capsule and 66.7% for bone mineralization. It was 100% for femoral neck fracture and osteonecrosis of the femoral head. CONCLUSION: This preliminary study suggests that pre-surgical MRI imaging should be considered as effective as CT for bone assessment of NHO and their features. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03832556. Registered February 6, 2019, https://clinicaltrials.gov/ct2/show/NCT03832556 .

Resection of heterotopic ossification around the hip after trauma.

Traumatic neurological lesions may lead to development of heterotopic ossification. These cases are classified as 'neurogenic heterotopic ossifications' (NHOs). The associated neurological lesions can be caused by cranial trauma or spinal cord injury and may sometimes include a local trauma.NHOs that form around the hip joints are of particular interest because they often cause the patient to avoid the sitting position or the resumption of walking.Whilst NHO can involve the knee, shoulder and elbow joints, hip-involving NHOs are more numerous, and sometimes develop in close contact with vascular or neurological structures.Multi-disciplinary clinical examination is fundamental to evaluate patients for surgical intervention and to define the objectives of the surgery. The best investigation to define an NHO mass is a computerized tomography (CT) scan.Resection is performed to liberate a fused joint to provide functionality, and this need not be exhaustive if it is not necessary to increase the range of motion.While recurrence does occur post-surgery, a partial resection does not pose a greater risk of recurrence and there are no adjuvant treatments available to reduce this risk.The greatest risks associated with NHO surgical resection are infection and haematoma; these risks are very high and must be considered when evaluating patients for surgery. Cite this article: EFORT Open Rev 2019;4 DOI: 10.1302/2058-5241.4.180098.

Phenol-Soluble Modulins Contribute to Early Sepsis Dissemination Not Late Local USA300-Osteomyelitis Severity in Rabbits.

INTRODUCTION: In bone and joint infections (BJIs), bacterial toxins are major virulence factors: Panton-Valentine leukocidin (PVL) expression leads to severe local damage, including bone distortion and abscesses, while α-hemolysin (Hla) production is associated with severe sepsis-related mortality. Recently, other toxins, namely phenol-soluble modulins (PSMs) expressed by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain USA300 (LAC WT) were shown to have ex vivo intracellular cytotoxic activity after S. aureus invasion of osteoblasts, but their in vivo contribution in a relatively PVL-sensitive osteomyelitis model remains poorly elucidated. MATERIALS AND METHODS: We compared the outcomes of experimental rabbit osteomyelitises induced with pvl+hla+psms+ LAC WT and its isogenic Δpsm derivatives (LAC Δpsmα and LAC Δpsmαßhld) using an inoculum of 3 × 108 CFUs. Mortality, hematogenous spread (blood culture, spleen and kidney), lung and bone involvements were assessed in two groups (non-survivors of severe sepsis and survivors sacrificed on day (D) 14). RESULTS: Severe sepsis-related mortality tended to be lower for Δpsm derivatives (Kaplan-Meier curves, P = .06). Non-survivors' bone LAC-Δpsmα (6.9 log10 CFUs/g of bone, P = .04) or -Δpsmαßhld (6.86 log10 CFUs/g of bone, P = .014) densities were significantly higher than LAC WT (6.43 log10 CFUs/g of bone). Conversely, lung Δpsmαßhld CFUs were significantly lower than LAC WT (P = .04). LAC Δpsmα, Δpsmαßhld and WT induced similar bone damage in D14 survivors, with comparable bacterial densities (respectively: 5.89, 5.91, and 6.15 log10 CFUs/g of bone). Meanwhile, pulmonary histological scores of inflammation were significantly higher for LAC Δpsmα- and Δpsmαßhld-infected rabbits compared to LAC WT (P = .04 and .01, respectively) but with comparable lung bacterial densities. CONCLUSION: Our experimental results showed that deactivating PSM peptides significantly limited bacterial dissemination from bone during the early phase of infection, but did not affect local severity of USA300 rabbit osteomyelitis.