Long, titanium, cemented stems decreased late periprosthetic fractures and revisions in patients with severe bone loss and previous revision.

PURPOSE: Long, cementless, femoral stem revisions are being used with increasing frequency. There is a relative lack of studies of late fractures after cementless implants, particularly in those patients who had a previous stem revision and are at higher risk for periprosthetic fracture after revision. In this paper, we review risk factors for periprosthetic fracture and revisions of long, cementless, locked stems and report implant survival compared with conventional, cemented, long-stem hip revision arthroplasties in such a group of patients. METHODS: We used data recorded in our institution. Between 1996 and 2002, 85 cementless femoral stem Aura™ (distal locked stem) prostheses were implanted in 85 patients. Of the 85 revisions with long, cementless stems, 32 were performed after one stem revision, 20 after two stem revisions and 12 after three stem revisions. Between 2003 and 2010, 124 femoral revision stems were performed in 124 patients using an extensively long, titanium femoral stem (Ceraver Osteal™). Kaplan-Meier analysis was used to determine implant survival. The Cox regression model was used to study risk factors for reoperation and revision. RESULTS: The increase in stem length corresponded to a mean of 4.5 ± 2.1 femoral canal diameters and was not significantly different (p = 0.02) between the two groups. Cardiopulmonary distress, intraoperative or postoperative complications were not significantly different between the two groups. There was an overall increased risk of pain, periprosthetic fractures and revision for the cementless prostheses compared with the cemented stems. With regard to thigh pain at the last follow-up, most patients (95 %) reported no pain in the cemented group, while 15 % of the cementless group experienced thigh pain under stress and 6 % had incapacitating pain. In the cemented group, stem re-revision was not required in any hip; there was no periprosthetic fracture; five stems had radiological loosening but in the absence of pain were not revised. Among patients of the cementless group, 21 % sustained failure or revision of their interlocked stem with periprosthetic fractures observed in 15 cases; factors which contributed significantly to a higher risk of fracture included the number of previous revisions; the average time between surgery and failure was 3.2 years after one revision, 2.8 years after two revisions, and 1.6 years after three revisions. CONCLUSIONS: The long, cementless, locked stem showed more early complications compared with recementing of long-stem prosthesis. We therefore recommend the use of cemented long stems in patients with severe bone loss and previous revision.

Stand-alone ALIF with integrated intracorporeal anchoring plates in the treatment of degenerative lumbar disc disease: a prospective study on 65 cases.

PURPOSE: ALIF with cages is expected to restore disc height and stabilize the spine promoting fusion, while avoiding damage attributed to rod-pedicle screw fixation. However, it may be related to an increased risk of fusion failure and subsidence. A prospective study was conducted by five investigators across three centers to confirm performance of a PEEK cage for stand-alone ALIF in the treatment of lumbar degenerative disc disease (DDD). METHODS: Sixty-five patients, with back ± leg pain, requiring surgery for DDD, were included. Efficacy and safety were evaluated at 6 weeks, 3, 6, and 12 months post-operatively. Fusion and subsidence were assessed through CT-images at 12-month follow-up. Disc height was measured. Clinical outcomes included back and leg pain (VAS), disability (Oswestry Disability Index), Quality of Life (Short-Form 36), and adverse events. RESULTS: The fusion and the subsidence rates were 96.3 and 2.0 %, respectively. ALIF surgery restored anterior and posterior disc height compared to baseline. There were no device-related serious adverse events, and no revision surgeries. Clinical outcomes improved significantly through 12-month follow-up. CONCLUSION: Safety and efficacy of this stand-alone cage with integrated intracorporeal plates was confirmed through 12 months for treatment of degenerative conditions. The design of the cage and plates may contribute to the decreased subsidence rate observed.

Bone union rate with recombinant human bone morphogenic protein-2 versus autologous iliac bone in PEEK cages for anterior lumbar interbody fusion.

PURPOSE: Autologous iliac crest bone graft (ICBG) is the gold standard material for spinal fusion. Bone graft substitutes, such as recombinant human bone morphogenic protein 2 (rhBMP-2) have been developed to promote spinal fusion and address morbidity issues related to ICBG harvesting. The objective of this study was to compare bone fusion rates after anterior lumbar interbody fusion (ALIF) between ICBG and rhBMP-2 by examining thin-cut computed tomography (CT) images at the one year follow-up. METHODS: Fifty one patients (62 levels) who underwent single- or two-level ALIF via the video-assisted minimally invasive anterior approach in our institution were assessed. Radiolucent cages were inserted in all cases. Each cage has a middle beam delimiting two chambers. Grafting was performed as follows: one chamber was filled with autologous ICBG, and the other chamber was filled with 6 mg of rhBMP-2. Thin-cut CT-scan multiplanar reconstruction analyses were performed to assess the rate and quality of bone fusion at one year of follow-up. RESULTS: Fusion was observed in 55 levels (88.7 %), with significant differences in fusion rates with rhBMP-2 and ICBG (71 % vs. 88.7 %) (P=0.001). Osteogenesis in the rhBMP-2 chamber had a centripetal pattern in all cases, leaving a central void in 97.7 % of cases representing 38.3 % of the surface of its chamber (range 0-80.3 %). In ICBG chambers, graft resorption was present in 44.4 %, representing 9.8 % of the chamber surface (range 0-52.2 %). CONCLUSION: RhBMP-2 was inferior to ICBG in terms of rate and quality of bone fusion in one- or two-level ALIF.

Morbidity of graft harvesting versus bone marrow aspiration in cell regenerative therapy.

PURPOSE: Using bone marrow mesenchymal stem cells (MSCs) with aspiration from the iliac crest is commonly used in reconstructive orthopaedic surgery. Because bone marrow aspiration is a percutaneous technique, the morbidity as compared with the classical bone graft should be decreased. METHOD: Therefore in a retrospective review of 523 consecutive cases of bone marrow aspiration performed at the Henri Mondor Hospital from 1990 to 2006 for the treatment of fractures, minor and major complications were identified and compared to the number of complications observed during the same period with 435 classical iliac crest bone graft procedures performed for the same indications of treatment of fractures. Minor complications included superficial infections, superficial seromas, and minor haematomas. Major complications included herniation of abdominal contents through massive bone graft donor sites, vascular injuries, deep infections at the donor site, neurologic injuries, deep haematoma formation requiring surgical intervention or transfusion, and iliac wing fractures. RESULT: Bone marrow aspiration decreased significantly the number of complications as compared with harvesting classical iliac crest bone graft that was associated with significant morbidity. Adverse events were significantly lower (p < 0.01) in the 523 procedures with bone marrow aspiration as compared with the 435 bone iliac crest piece harvesting. This was true for anaemia (16 cases versus 87 cases), for early pain (six versus 152), persistent pain (two versus 21), neuralgia (three versus 11), minor complications (ten versus 56), and major complications (three cases versus 22 cases). CONCLUSION: In our series the number of complications with bone marrow aspiration was ten times less than the complications observed with the classical technique of bone piece harvesting from the iliac crest, and the complications were clearly less severe.

Analysis of intraoperative difficulties and management of operative complications in revision anterior exposure of the lumbar spine: a report of 25 consecutive cases.

PURPOSE: After a first anterior approach to the lumbar spine, formation of adhesions of soft tissues to the spine increases the surgical difficulties and potential for iatrogenic injury during the revision exposure. The objective of this study was to identify the intraoperative difficulties and postoperative complications associated with revision anterior lumbar spine procedures in a single institution. METHODS: This is a retrospective review of 25 consecutive anterior revision lumbar surgeries in 22 patients (7 men and 15 women) operated on between 1998 and 2011. Patients with trauma or malignancies were excluded. The mean age of the patients at the time of revision surgery was 56 years (range 20-80 years). The complications were analyzed depending on the operative level and the time between the index surgery and the revision. RESULTS: Six major complications (five intraoperatively and one postoperatively) occurred in five patients (20 %): three vein lacerations (12 %) and two ureteral injuries (8 %), despite the presence of a double-J ureteral stent. The three vein damages were repaired or ligated by a vascular surgeon. One of the two ureteral injuries led to a secondary nephrectomy after end-to-end anastomosis failure; the other necessitated secondary laparotomy for small bowel obstruction. CONCLUSIONS: Anterior revision of the lumbar spine is technically challenging and is associated with a high rate of vascular or urologic complications. Therefore, the potential complications of the procedure must be weighted against its benefits. When iterative anterior lumbar approach is mandatory, exposure should be performed by an access surgeon in specialized centers that have ready access to vascular and urologic surgeons.

An uncommon case of Mycoplasma hominis infection after total disc replacement.

PURPOSE: Beside mechanical complications, the majority of adverse events after total disc arthroplasty (TDA) are related to the surgical approach. Septic complications are very uncommon and only one previous case has been published. The objective of this article is to describe the clinical circumstances, treatment, and outcomes of septic complication after TDA at L4-L5, involving an uncommon pathogen (Mycoplasma hominis). METHODS: A 38-year-old woman underwent a MobiDisc(®) TDA at L4-L5 level for discogenic pain. One month postoperatively, she complained of acute low back and abdominal pain associated with fever (39 °C). C-reactive protein level was elevated (197 mg/L; normal <5 mg/L) and the white blood cell count was normal (7 × 10(9)/L; normal 4-10 × 10(9)/L). A computerized tomography (CT) showed a left psoas-based retroperitoneal abscess. Treatment consisted of open debridement, drainage and empirical antibiotic therapy. Intraoperative cultures yielded M. hominis after 7 days incubation. Antibiotic therapy was adapted and discontinued after 2 months. The patient had failed to mention earlier that she had been suffering from abnormal vaginal discharge for some time and was using an intrauterine contraceptive device. RESULTS: At 1.5-year follow-up, review confirmed healing of the infection with biological normalization without residual collection, radiolucent lines or osteolysis around the prosthesis at radiographs, CT and MRI. CONCLUSIONS: Mycoplasma hominis can be involved as an extragenital pathogen in musculoskeletal infections. Because its culture and identification are difficult, special media and real-time PCR are required in case of postoperative deep wound infection after anterior lumbar spine surgery, especially in the case of previous genitourinary infections, to decrease the delay in diagnosis and treatment.

Treatment of spinal epidural compression due to hematological malignancies: a single institution's retrospective experience.

PURPOSE: To analyze the neurological and mechanical outcomes in 44 consecutive patients treated for a hematological malignancy with epidural localization to assess the place of surgery in the treatment of this pathology. METHODS: Clinical records, CT and MRI scans of 44 patients with epidural localizations of multiple myeloma or lymphoma treated between 1990 and 2005 were analyzed retrospectively. Neurological status, epiduritis and osteolysis volumes, vertebral collapse, and spinal canal compromise were assessed. The neurological outcome was graded according to Frankel and the mechanical outcome was evaluated on the rate of vertebral collapse. RESULTS: Surgery was performed in 11 patients (25 %) for neurological (n = 9) or mechanical (n = 2) reasons. In five cases, a concomitant biopsy was performed because the etiology of the epiduritis was unknown. Fifteen patients (34.1 %) presented with a neurological deficit secondary to an acute vertebral collapse (n = 4), an epiduritis (n = 7), or both (n = 4). Whatever the treatment (surgical or not), a complete recovery (Frankel E) occurred in 14/15 (93.3 %) after a mean delay of 12 weeks (range 2-24 weeks). During the follow-up, seven collapses occurred. We estimated that a threshold of 30 % of osteolysis was associated with a significant risk of vertebral collapse (P = 0.005). CONCLUSIONS: Hematological malignancies with epidural localization must be treated first medically, even in patients with neurological symptoms. Surgery should be considered only in the cases of acute vertebral collapse, medical treatment failure, or to prevent acute collapse in patients with vertebral osteolysis of more than 30 %.

Coracoid process x-ray investigation before Latarjet procedure: a radioanatomic study.

BACKGROUND: The purpose of this study was to determine whether a preoperative radiologic assessment of the coracoid process is predictive of the amount of bone available for coracoid transfer by the Latarjet procedure. MATERIAL: Thirty-five patients with anterior instability undergoing a Latarjet procedure were included. A preoperative radiologic assessment was performed with the Bernageau and true anteroposterior (true AP) views. METHODS: The length of the coracoid process was measured on both radiographic views and the values were compared with the length of the bone block during surgery. Statistical analysis was carried out by ANOVA and Wilcoxon tests (P < .05). RESULTS: On radiologic examination, the mean coracoid process length was 29 ± 4 and 33 ± 4 mm on the Bernageau and true AP views, respectively. The mean bone block length during surgery was 21.6 ± 2.7 mm. A significant correlation was found (P = .032) between the coracoid process length on the true AP view and the intraoperative bone block length. DISCUSSION: Preoperative planning for the Latarjet procedure, including graft orientation and screw placement, requires knowledge of the length of coracoid bone available for transfer. This can be facilitated with the use of preoperative standard radiographs, thus avoiding computed tomography. This planning allows the detection of coracoid process anatomic variations or the analysis of the remaining part of the coracoid process after failure of a first Latarjet procedure to avoid an iliac bone graft. CONCLUSION: Radiologic preoperative coracoid process measurement is an easy, reliable method to aid preoperative planning of the Latarjet procedure in primary surgery and reoperations.

Benefits of small volume and small syringe for bone marrow aspirations of mesenchymal stem cells.

PURPOSE: Aspirating bone marrow from the iliac crest using small volumes of 1-4 ml with a 10-ml syringe has been historically proposed for harvesting adult mesenchymal stem cells and described as a standard technique to avoid blood dilution. The disadvantage of repeated small aspirations is that there is a significantly increased time to harvest the bone marrow. However, it is not known if a large volume syringe can improve the rate of bone marrow aspiration without increasing blood dilution, thus reducing the quality of the aspirate. We compared the concentrations of mesenchymal stem cells obtained under normal conditions with two different size syringes. METHODS: Thirty adults (16 men and 14 women with a mean age of 49 ± 14 years) underwent surgery with aspiration of bone marrow from their iliac crest. Bilateral aspirates were obtained from the iliac crest of the same patients with a 10-ml syringe and a 50-ml syringe. Cell analysis determined the frequencies of mesenchymal stem cells (as determined by the number of colonies) from each size of syringe. The cell count, progenitor cell concentration (colonies/ml marrow) and progenitor cell frequency (per million nucleated cells) were calculated. All bone marrow aspirates were harvested by the same surgeon. RESULTS: Aspirates of bone marrow demonstrated greater concentrations of mesenchymal stem cells with a 10-ml syringe compared with matched controls using a 50-ml syringe. Progenitor cell concentrations were on average 300 % higher using a 10-ml syringe than matched controls using a 50-ml syringe (p < 0.01). CONCLUSIONS: In normal human donors, bone marrow aspiration from 30 patients demonstrated a reduced mesenchymal stem cell number in aspirates obtained using a larger volume syringe (50 ml) as compared with a smaller volume syringe (10 ml).

The risk of dislocation after total hip arthroplasty for fractures is decreased with retentive cups.

PURPOSE: Total hip arthroplasty (THA) has been efficacious for treating hip fractures in healthy older patients. However, in those patients with fractures a widely variable prevalence of dislocation has been reported, partly because of varying durations of follow up for this specific end-point. The purpose of the present study was to determine the cumulative risk of dislocation in these patients with fractures and to investigate if retentive cups decrease the risk of dislocation. METHODS: Between 2000 and 2005, 325 patients with neck fracture underwent primary THA using a retentive (325 hips) cup. The results of these 325 acetabular cups were compared to 180 THA without retentive cups performed for neck fractures in the same hospital between 1995 and 2000 by the same surgical team. The mean age of the 505 patients was 75 years (range 65-85). All patients were followed for a minimum of five years for radiographic evidence of implant failure. The patients were followed at routine intervals and were specifically queried about dislocation. The cumulative risk of dislocation and recurrent dislocation was calculated with use of the Kaplan-Meier method. RESULTS: For patients without retentive cups, the cumulative risk of a first-time dislocation was 5 % at one month and 12 % at one year and then rose at a constant rate of approximately 1 % every year to 16 % at five years. For patients with retentive cups, the cumulative risk of a first-time dislocation was 1 % at one month, 2 % at one year and then did not changed at five years. There were no differences in the mortality rates or in loosening rates among the treatment groups. The rate of secondary surgery was highest in the group without retentive (10 % for recurrent dislocation) compared with 1 % in the group treated with retentive cups. In absence of retentive cups, multivariate analysis revealed that the relative risk of dislocation for female patients (as compared with male patients) was 2.1 and that the relative risk for patients who were 80 years old or more (as compared with those who were less than 80 years old) was 1.5. Two underlying diagnoses occurring during follow up-cognitively impaired patients or neurologic disease-were also associated with a significantly greater risk of dislocation in absence of retentive cup. For these patients the risk was also decreased with a retentive cup. CONCLUSION: With standard cups the incidence of dislocation is highest in the first year after arthroplasty and then continues at a relatively constant rate for the life of the arthroplasty. Patients at highest risk are old female patients and those with a diagnosis of neurologic disease. Retentive cups in these patients are an effective technique to prevent post-operative hip dislocation.

Effects of lumbar artificial disc design on intervertebral mobility: in vivo comparison between mobile-core and fixed-core.

Although in theory, the differences in design between fixed-core and mobile-core prostheses should influence motion restoration, in vivo kinematic differences linked with prosthesis design remained unclear. The aim of this study was to investigate the rationale that the mobile-core design seems more likely to restore physiological motion since the translation of the core could help to mimic the kinematic effects of the natural nucleus. In vivo intervertebral motion characteristics of levels implanted with the mobile-core prosthesis were compared with untreated levels of the same population, levels treated by a fixed-core prosthesis, and normal levels (data from literature). Patients had a single-level implantation at L4L5 or L5S1 including 72 levels with a mobile-core prosthesis and 33 levels with a fixed-core prosthesis. Intervertebral mobility characteristics included the range of motion (ROM), the motion distribution between flexion and extension, the prosthesis core translation (CT), and the intervertebral translation (VT). A method adapted to the implanted segments was developed to measure the VT: metal landmarks were used instead of the bony landmarks. The reliability assessment of the VT measurement method showed no difference between three observers (p < 0.001), a high level of agreement (ICC = 0.908) and an interobserver precision of 0.2 mm. Based on this accurate method, this in vivo study demonstrated that the mobile-core prosthesis replicated physiological VT at L4L5 levels but not at L5S1 levels, and that the fixed-core prosthesis did not replicate physiological VT at any level by increasing VT. As the VT decreased when the CT increased (p < 0.001) it was proven that the core mobility minimized the VT. Furthermore, some physiologic mechanical behaviors seemed to be maintained: the VT was higher at implanted the L4L5 level than at the implanted L5S1 level, and the CT appeared lower at the L4L5 level than at the L5S1 level. ROM and motion distribution were not different between the mobile-core prosthesis and the fixed-core prosthesis implanted levels. This study validated in vivo the concept that a mobile-core helps to restore some physiological mechanical characteristics of the VT at the implanted L4L5 level, but also showed that the minimizing effect of core mobility on the VT was not sufficient at the L5S1 level.

Anterior lumbar fusion techniques: ALIF, OLIF, DLIF, LLIF, IXLIF.

An anterior approach to the lumbar spine is increasingly used in performing fusion. Depending on the level to be treated, several approaches have been developed to deal with the anatomic obstacles encountered: pure anterior, oblique anterior or lateral, and trans- or pre-psoas. Conventional techniques incur risk of muscle lesion and severe bleeding, and have been replaced by minimally invasive approaches, often with video assistance after rapid closure of laparoscopic approaches with gas insufflation. There has, in parallel, been great progress in anterior spinal instrumentation systems. Non-existent when these techniques were first developed, they have become increasingly sophisticated, and now employ a variety of stand-alone or not cages and anterior screwed plate that can be associated together or to posterior fixation. Each approach and type of fixation has its specific technical requirements that need to be fully mastered so as to minimize risk, especially regarding vessels, and to enable the patient to enjoy the benefit of their very low morbidity. We shall therefore detail here each step of the pure anterior approach, which is most often used for L5S1, the oblique and lateral approaches, mainly used for L2L5, and also the preparation of the lumbar spine for anterior interbody fusion, with the respective instrumentations. We shall then consider the pros, cons and risks, and also spinal or general contraindications that may sometimes preclude this option. From this, we shall derive the specific optimal and wrong indications for anterior lumbar surgery, to help decision-making when fusion is indicated.

French Spine Surgery Society guidelines for management of spinal surgeries during COVID-19 pandemic.

Since the outbreak of coronavirus disease 2019 (COVID-19) in December 2019 in China, various measures have been adopted in order to attenuate the impact of the virus on the population. With regard to spine surgery, French physicians are devoted to take place in the national plan against COVID-19, the French Spine Surgery Society therefore decided to elaborate specific guidelines for management of spinal disorders during COVID-19 pandemic in order to prioritize management of patients. A three levels stratification was elaborated with Level I: Urgent surgical indications, Level II: Surgical indications associated to a potential loss of chance for the patient and Level III: Non-urgent surgical indications. We also report French experience in a COVID-19 cluster region illustrated by two clinical cases. We hope that the guidelines formulated by the French Spine Surgery Society and the experience of spine surgeons from a cluster region will be helpful in order optimizing the management of patients with urgent spinal conditions during the pandemic.

Total shoulder arthroplasty using the superior approach: influence on glenoid loosening and superior migration in the long-term follow-up after Neer II prosthesis installation.

Glenoid component loosening and superior humeral translation are common after Neer II total shoulder arthroplasty using the anterior approach. To determine whether the superior approach reduced these complications, we retrospectively reviewed 20 shoulders in 16 patients. Both components were cemented. Patient satisfaction, unweighted Constant score, and imaging studies were evaluated at a mean of 3.5 years and at a mean of 11.1 years. Fourteen patients were satisfied or very satisfied. The mean unweighted Constant score improved from 25/100 preoperatively to 57/100 after 3.5 years and to 51/100 after 11.1 years. Pain relief contrasted with low strength. Radiolucent lines appeared around 95% of glenoid components and 20% of humeral stems. Computed tomography showed severe glenoid osteolysis in 3 of 13 shoulders. Humeral superior translation did not occur. This study confirms the glenoid component fixation issue. The superior approach may reduce the risk of humeral superior translation and radiologic glenoid component loosening.

Osteonecrosis repair with bone marrow cell therapies: state of the clinical art.

INTRODUCTION: Hip osteonecrosis is a pathological condition resulting from cellular impairment due to reduction in osteoblast activity and local mesenchymal stem cell populations. Cell-based therapies might aid in overcoming these deficiencies by providing stem cells and other progenitor cells to potentially improve the local cellular environment in the affected hip. METHODS: A PubMed search, using the search terms "hip osteonecrosis" and "mesenchymal stem cells", was conducted in December 2013. A total of 15 publications were identified and reviewed for clinical outcomes. FINDINGS: Clinical studies of patients with osteonecrosis treated with mesenchymal stem cells showed beneficial effects. No unexpected adverse events were identified in these studies. Core decompression was the usual method for autologous bone marrow cell implantation into the femoral head. However, other methods have been used such as arterial or venous delivery. A rationale for the use of cytotherapy, as well as the different descriptions of the techniques of implantation MSCs (autologous vs. allogenic, concentration vs. expansion), is provided in the context of treating hip osteonecrosis. Current problems and future challenges with cytotherapy and associated techniques are discussed. This article is part of a Special Issue entitled "Stem Cells and Bones".

Minimally invasive anterior lumbar interbody fusion for adult degenerative scoliosis with 1 or 2 dislocated levels.

OBJECT: Frequent complications of posterolateral instrumented fusion have been reported after treatment of degenerative scoliosis in elderly patients. Considering that in some cases, most of the symptomatology of adult degenerative scoliosis (ADS) is a consequence of the segmental instability at the dislocated level, the use of minimally invasive anterior lumbar interbody fusion (ALIF) to manage symptoms can be advocated to reduce surgical morbidity. The purpose of this study was to evaluate the midterm outcomes of 1- or 2-level minimally invasive ALIFs in ADS patients with 1- or 2-level dislocations. METHODS: A total of 47 patients (average age 64 years; range 43-80 years) with 1- or 2-level ALIF performed for ADS (64 levels) in a single institution were included in the study. An independent spine surgeon retrospectively reviewed all the patients' medical records and radiographs to assess operative data and surgery-related complications. Clinical outcome was reported using the Oswestry Disability Index (ODI) and the visual analog scale (VAS) for lumbar and leg pain. Intraoperative data and complications were collected. Fusion and risk for adjacent-level degeneration were assessed. RESULTS: The mean follow-up duration was 3 years (range 1-10 years). ODI, and back and leg pain VAS scores were significantly improved at last follow-up. A majority of patients (74%) had a statistically significant improvement in their ODI score of more than 20 points at latest follow-up and 1 had a worsening of his disability. The mean operating time was 166 minutes (range 70-355 minutes). The mean estimated blood loss was 410 ml (range 50-1700 ml). Six (5 major and 1 minor) surgical complications (12.7% of patients) and 13 (2 major and 11 minor) medical complications (27.7% of patients) occurred without death or wound infection. Fusion was achieved in 46 of 47 patients. Surgery resulted in a slight but significant decrease of the Cobb angle, and improved the pelvic parameters and lumbar lordosis, but had no effect on the global sagittal balance. At latest follow-up, 9 patients (19.1%) developed adjacent-segment disease at a mean of 2 years' delay from the index surgery; 4 were symptomatic but treated medically, and none required iterative surgery. CONCLUSIONS: Single- or 2-level minimally invasive fusion through a minimally invasive anterior approach in some selected cases of ADS produced a good functional outcome with a high fusion rate. They were associated with a significantly lower rate of complications in this study than the historical control.

Revision total hip arthroplasty performed after fracture of a ceramic femoral head. A multicenter survivorship study.

BACKGROUND: The alumina ceramic femoral head was introduced for total hip arthroplasty approximately thirty years ago. One of its main drawbacks was the risk of implant fracture. The aim of this study was to examine the results of revision total hip replacement performed specifically to treat a fracture of a ceramic femoral head and to identify technical factors that affected the outcomes. METHODS: One hundred and five surgical revisions to treat a fracture of a ceramic femoral head, performed at thirty-five institutions, were studied. The patients were examined clinically by the operating surgeon at the time of the last follow-up. The surgeon provided the latest follow-up radiographs, which were compared with the immediate postoperative radiographs. The success of the revisions was assessed with Kaplan-Meier survivorship analysis, with the need for repeat revision as the end point. We evaluated the complication rate and radiographic changes indicative of implant loosening. The average duration of follow-up between the index revision and the last clinical and radiographic review was 3.5 years (range, six months to twenty years). RESULTS: Following the revisions, radiographic evidence of cup loosening was seen in twenty-two hips (21%) and radiographic evidence of femoral loosening was seen in twenty-two (21%). One or several repeat revisions were necessary in thirty-three patients (31%) because of infection (four patients), implant loosening (twenty), osteolysis (eight), or fracture of the revision femoral head component (one). The survival rate at five years was 63% (95% confidence interval, 51% to 75%). The survival rate was significantly worse when the cup had not been changed, when the new femoral head was made of stainless steel, when a total synovectomy had not been done, and when the patient was less than fifty years old. CONCLUSIONS: Fracture of a ceramic femoral head component is a rare but potentially serious event. A suitable surgical approach, including total synovectomy, cup exchange, and insertion of a cobalt-chromium or new ceramic femoral ball minimizes the chance of early loosening of the implants and the need for one or more repeat revisions. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series [no, or historical, control group]).

Variation of the impact duration during the in vitro insertion of acetabular cup implants.

The acetabular cup (AC) is an implant impacted into a bone cavity and used for hip prosthesis surgery. Initial stability of the AC is an important factor for long term surgical success. The aim of this study is to determine the variations of the impact duration during AC implant insertion. Twenty-two bone samples taken from bovine femurs were prepared ex vivo for the insertion of an acetabular cup implant, following the surgical procedure used in the clinic. For each bone sample, ten impacts were applied using reproducible mass falls (3.5 kg) in order to insert the AC implant. Each impact duration was recorded using a wide bandwidth force sensor. For all bone samples, the impact duration was shown to first decrease as a function of the impact number, then reaching a stationary value equal in average to 4.2±0.7 ms after an average number of 4.1±1.7 impacts. The impact duration may be related to variations of the bone-implant interface contact rigidity because of an increase the amount of bone tissue in contact with the AC implant. Measurements of impact duration have a good potentiality for clinical application to assist the surgeon during the insertion of the AC implant, providing valuable information on the bone-implant interface contact properties.

Does core mobility of lumbar total disc arthroplasty influence sagittal and frontal intervertebral displacement? Radiologic comparison with fixed-core prosthesis.

BACKGROUND: An artificial disc prosthesis is thought to restore segmental motion in the lumbar spine. However, it is reported that disc prosthesis can increase the intervertebral translation (VT). The concept of the mobile-core prosthesis is to mimic the kinematic effects of the migration of the natural nucleus and therefore core mobility should minimize the VT. This study explored the hypothesis that core translation should influence VT and that a mobile core prosthesis may facilitate physiological motion. METHODS: Vertebral translation (measured with a new method presented here), core translation, range of motion (ROM), and distribution of flexion-extension were measured on flexion-extension, neutral standing, and lateral bending films in 89 patients (63 mobile-core [M]; 33 fixed-core [F]). RESULTS: At L4-5 levels the VT with M was lower than with F and similar to the VT of untreated levels. At L5-S1 levels the VT with M was lower than with F but was significantly different compared to untreated levels. At M levels a strong correlation was found between VT and core translation; the VT decreases as the core translation increases. At F levels the VT increases as the ROM increases. No significant difference was found between the ROM of untreated levels and levels implanted with either M or F. Regarding the mobility distribution with M and F we observed a deficit in extension at L5-S1 levels and a similar distribution at L4-5 levels compared to untreated levels. CONCLUSION: The intervertebral mobility was different between M and F. The M at L4-5 levels succeeded to replicate mobility similar to L4-5 untreated levels. The M at L5-S1 succeeded in ROM, but failed regarding VT and mobility distribution. Nevertheless M minimized VT at L5-S1 levels. The F increased VT at both L4-5 and L5-S1. CLINICAL RELEVANCE: This study validates the concept that the core translation of an artificial lumbar disc prosthesis minimizes the VT.

Surgical treatment of destructive cervical spondyloarthropathy with neurologic impairment in hemodialysis patients.

STUDY DESIGN: We have retrospectively reviewed 11 chronic hemodialysis patients with cervical destructive spondyloarthropathy responsible for neural impairment 1 year after surgery and at last follow-up. OBJECTIVE: To evaluate clinical and radiologic outcomes, and necessity of vertebral block excision. SUMMARY OF BACKGROUND DATA: Destructive spondyloarthropathy of the cervical spine is associated with long-term hemodialysis for chronic kidney failure. Spinal cord compression and neurologic troubles occur in a few cases. Surgical treatment remains controversial because these are debilitated patients with multiple organ failures. METHODS: All 11 patients had unstable cervical spondylolisthesis, and 10 had kyphotic vertebral fusion involving at least 2 vertebrae. We performed interbody bone grafting (cement in 1 case) and stabilized with a plate. In 6 of the 10 patients with vertebral block, excision of the block was performed. RESULTS: No patients were lost to follow-up. One patient died 2 days after the operation. There were 2 other patients who required early surgical revision (i.e., a corporectomy followed by early graft expulsion). Bone healing settled in all patients. One year after surgery, patients had almost complete resolution of the pain and satisfactory neurologic recovery. Improvement was evaluated according to the Nurick classification. CONCLUSION: Functional and neurologic results were similar whether the patients did or did not undergo vertebral block excision, suggesting that stabilizing the unstable level may be sufficient in patients with neurologic impairment. Excision of spontaneous vertebral blocks should be avoided to minimize the morbidity of surgery in these debilitated patients with a limited life expectancy.