Exploratory study of the lateral body sway predictability as frame of reference for gait rehabilitation following a total knee arthroplasty.

AIMS: The aim of the present study was to investigate whether the predictability of fronto-parallel trunk rotations (lateral body sway) could serve as a frame of reference to monitor recovery after total knee arthroplasty (TKA). METHODS: Before surgery, 11 TKA patients were asked to perform a treadmill walking task at three different speeds. In addition, their gait abilities were scored on three standard clinical walking tests. The treadmill walking task was repeated at three different timepoints following surgery, i.e., at 3, 6 and 12 months post-TKA. The movements of the trunk were digitized with an inertial sensor to capture the amplitude and the sample entropy (SEn) of the lateral body sway that were evaluated in separate ANOVAs. RESULTS: Before surgery the TKA group showed larger body sway (P = 0.025) with smaller SEn values (P = 0.038), which both restored to levels of healthy adults in the 12 months following surgery. Systematic correlations between the SEn values and the clinical test scores were found. CONCLUSIONS: The current findings show that movement behavior of the trunk in the fronto-parallel plane was affected by knee osteoarthritis and suggest that the predictability of the lateral body sway may serve as an index of recovery after TKA.

Instability Severity Index Score predicts recurrent shoulder instability after arthroscopic Bankart repair.

PURPOSE: The Instability Severity Index (ISI) Score was developed to preoperatively assess the risk of recurrent shoulder instability after an arthroscopic Bankart repair. This study aims to validate the use of ISI Score for predicting the risk of recurrence after an arthroscopic Bankart repair in a heterogeneous population and proposes an appropriate cut-off point for treating patients with an arthroscopic Bankart repair or otherwise. METHODS: This study analysed 99 shoulders after a traumatic dislocation that underwent arthroscopic Bankart repair with at least 3 years follow-up. Patients were divided into subcategories based on their respective ISI Score. Recurrence includes either a postoperative dislocation or perceived instability. RESULTS: The overall recurrence rate was found to be 26.3%. A significant correlation was identified between ISI Score and the recurrence rate (odds ratio [OR]: 1.545, 95% confidence interval [CI]: 1.231-1.939, p < 0.001). Furthermore, ISI Score 4-6 (OR: 4.498, 95% CI: 1.866-10.842, p < 0.001) and ISI Score > 6 (OR: 7.076, 95% CI: 2.393-20.924, p < 0.001) both had a significantly higher risk of recurrence compared to ISI Score 0-3. In ISI Score subcategories 0-3, 4-6 and >6, the recurrence rate was, respectively, 15.4%, 40.7% and 71.4%. CONCLUSION: ISI Score has predictive value in determining the recurrence risk of shoulder instability following an arthroscopic Bankart repair in a heterogeneous population. Based on the findings of this study, we recommend using arthroscopic Bankart repair in patients with ISI Score 0-3. Clinical and shared decision-making are essential in the group with ISI Score 4-6, since the recurrence rate is significantly higher than in patients with ISI Score 0-3. Arthroscopic Bankart repair is not suitable for patients with ISI Score > 6. LEVEL OF EVIDENCE: Level III.

Inertial-Sensor-Based Monitoring of Sample Entropy and Peak Frequency Changes in Treadmill Walking during Recovery after Total Knee Arthroplasty.

This study aimed to investigate whether sample entropy (SEn) and peak frequency values observed in treadmill walking could provide physical therapists valuable insights into gait rehabilitation following total knee arthroplasty (TKA). It was recognized that identifying movement strategies that during rehabilitation are initially adaptive but later start to hamper full recovery is critical to meet the clinical goals and minimize the risk of contralateral TKA. Eleven TKA patients were asked to perform clinical walking tests and a treadmill walking task at four different points in time (pre-TKA, 3, 6, and 12 months post-TKA). Eleven healthy peers served as the reference group. The movements of the legs were digitized with inertial sensors and SEn and peak frequency of the recorded rotational velocity-time functions were analyzed in the sagittal plane. SEn displayed a systematic increase during recovery in TKA patients (p < 0.001). Furthermore, lower peak frequency (p = 0.01) and sample entropy (p = 0.028) were found during recovery for the TKA leg. Movement strategies that initially are adaptive, and later hamper recovery, tend to diminish after 12 months post-TKA. It is concluded that inertial-sensor-based SEn and peak frequency analyses of treadmill walking enrich the assessment of movement rehabilitation after TKA.

More Predictable and Less Automatized Movements during Walking -not during Repetitive Punching- in Knee Osteoarthritis.

Using the non-affected leg as stable frame of reference for the affected leg in gait assessment in knee osteoarthritis (KO) fails due to compensatory mechanisms. Assessing the cyclical movements of the upper extremities in a frequency-controlled repetitive punching task may provide an alternative frame of reference in gait assessment in patients with KO. Eleven participants with unilateral KO and eleven healthy controls were asked to perform treadmill walking and repetitive punching. The KO group showed more predictable (p = 0.020) and less automatized (p = 0.007) movement behavior than controls during treadmill walking. During repetitive punching, the KO group showed a similar degree of predictability (p = 0.784) but relative more automatized movement behavior (p = 0.013). Thus, the predictability of the movement behavior of the upper extremities during repetitive punching seems unaffected by KO and could provide an alternative frame of reference in gait assessment in patients with KO.

Acute haematogenous periprosthetic joint infection due to Streptococcus sanguinis along with coexistent crystalline arthropathy after total knee arthroplasty: a rare combination.

A man in his 60s, with a medical history of gout, underwent total knee arthroplasty of his right knee followed by expeditious rehabilitation. Seven months after surgery, he was referred to the emergency ward with sudden onset of pain and swelling of his right knee accompanied with fever. Further inquiry revealed no trauma, infection or skin lesions besides a tongue bite several weeks earlier. An impaired range motion of the knee was seen on physical examination along with a tachycardia. Laboratory studies showed a C reactive protein of 345 mg/L, after which a debridement, antibiotics and implant retention procedure was performed. Intraoperatively obtained synovial fluid showed monosodium urate crystals consistent with crystalline arthropathy (ie, gout). However, unexpectedly, Streptococcus sanguinis was identified in all microbiological cultures too, confirming a coexistent periprosthetic joint infection. After comprehensive antibiotic treatment and gout flare therapy, this patient made a full recovery with retention of the implant.

Increased Speed Elicited More Automatized but Less Predictable Control in Cyclical Arm and Leg Movements.

The present study explores variations in the degree of automaticity and predictability of cyclical arm and leg movements. Twenty healthy adults were asked to walk on a treadmill at a lower-than-preferred speed, their preferred speed, and at a higher-than-preferred speed. In a separate, repetitive punching task, the three walking frequencies were used to cue the target pace of the cyclical arm movements. Movements of the arms, legs, and trunk were digitized with inertial sensors. Whereas absolute slope values (|ß|) of the linear fit to the power spectrum of the digitized movements (p < .001, η2 = .676) were systematically smaller in treadmill walking than in repetitive punching, sample entropy measures (p < .001, η2 = .570) were larger reflecting the former task being more automated but also less predictable than the latter task. In both tasks, increased speeds enhanced automatized control (p < .001, η2 = .475) but reduced movement predictability (p = .008, η2 = .225). The latter findings are potentially relevant when evaluating effects of task demand changes in clinical contexts.

Sacroiliac joint fusion in patients with Ehlers Danlos Syndrome: A case series.

BACKGROUND: Sacroiliac joint dysfunction (SJD) is a known cause of lower back pain. SJD might be due to hypermobility in the Sacroiliac joint (SIJ) in patients with Ehlers Danlos Syndrome (EDS). Stabilization of the SIJ can be a highly successful treatment for lower back pain. No previous literature about EDS and SIJ fusion is available. The purpose of this study was to assess our mid-term results of SIJ fusion surgery in EDS patients suffering from SIJ dysfunction. METHODS: A case series of patients who underwent SIJ fusion for SIJ dysfunction due to EDS between January 2012 and December 2018 were analyzed in retrospect. Patients underwent surgery and the SIJ was stabilized with triangular implants bridging the joint. Pain and functional outcomes were assessed in nine agree/disagree questions and a satisfaction performance scale. Clinical data has been extracted from the patient files and in addition, we reassessed the position of the implants on the CT scans. RESULTS: A total of 16 patients with EDS completed the questionnaire and were available for analysis. The mean satisfaction score is 78.1 out of 100 and seven patients reported a 100% satisfaction score. CONCLUSION: SIJ fusion is a safe and useful procedure to reduce pain and function levels in EDS patients with lower back pain due to SIJ dysfunction.

The effect of a fibrin sealant on knee function after total knee replacement surgery. Results from the FIRST trial. A multicenter randomized controlled trial.

BACKGROUND: Total knee replacement (TKR) is increasingly performed in short term hospital stay, making same day mobilization an important issue is after surgery. This implies little joint effusion by reducing intra-articular blood loss, which will enhance knee range of motion. The application of a topical fibrin sealant on the intraoperative bare bone and synovial tissue may contribute to better early full mobilization and thus improved functional outcomes. Since ambulation with a fully extended knee is less strenuous, we hypothesized that patients who received fibrin sealant would demonstrate improved early knee extension after six weeks compared to patients who received standard care. METHODS: A multicenter randomized controlled trial in a consecutive series of osteoarthritis patients scheduled for TKR surgery. Participants were randomized to receive fibrin sealant or not before closing the knee joint capsule. Primary outcome was change in knee extension angle(°) at short term (2 weeks) follow-up (cExt). Secondary outcomes were 6-week extension angle, knee flexion angle, hemoglobin loss, blood transfusion rates, complication rates, the Knee Society Score, and the KOOS and EQ5D questionnaires. RESULTS: When data on primary outcome became available from 250 patients, an interim analysis was performed by an independent Data Safety Monitoring Board for safety and effectivity assessment. This analysis showed that sufficient patients were included to detect a cExt of 10° between both groups. Inclusion was stopped however, all in the meantime included patients were treated according to their randomization. A total of 466 were available for analysis. Both groups were comparable in terms of baseline characteristics. The estimated mean cExt difference was 0.2° (95%CI -0.5 to 0.9). No differences in secondary outcomes were found. CONCLUSIONS: No beneficial effects or side effects were found of a topically applied fibrin sealant during TKR surgery. These results discourage the clinical use of a fibrin sealant in TKR. TRIAL REGISTRATION: Dutch Trial Register, NTR2500.

Self-Warming Blanket Versus Forced-Air Warming in Primary Knee or Hip Replacement: A Randomized Controlled Non-Inferiority Study.

OBJECTIVE: After primary total knee/hip replacement (TKR or THR respectively) a prosthetic joint infection (PJI) could develop. Hypothermia could raise the risk of infection. Heating by forced-air can disrupt laminar airfl ow in the operation room (OR), potentially raising the risk of infection. We aimed to study non-inferiority of an active self-heating blanket (SHB) compared to a forced-air blanket (FAB) in preventing hypothermia. METHODS: A randomized controlled non-inferiority trial (N = 86 patients) was performed comparing a SHB versus a FAB in elective primary TKR/THR patients. Primary outcome was lowest measured temperature during surgery. Secondary outcomes were patients' core temperature before, during, and after surgery, thermal comfort visual analogue score (VAS) and complications during hospitalization. RESULTS: Lowest measured temperature was 35.9°C (± 0.6) in SHB and 36.1°C (± 0.5) in FAB group (p = 0.05). No signifi cant correlation was found with duration of surgery or temperature of the OR. No signifi cant difference in core temperature was found before surgery (SHB = 36.8°C [± 0.4], FAB = 36.8°C [± 0.5], p = 0.49), after induction of anaesthesia (SHB = 36.6°C [± 0.5], FAB = 36.7°C [± 0.5], p = 0.22) nor as a mean during surgery (SHB = 35.8°C [± 1.6], FAB = 36.0°C [± 1.3], p = 0.68). SHB patients were "colder" at the recovery bay, 35.8°C (± 0.6) compared to FAB patients, 36.1°C (± 0.5) (p = 0.04). Mean VAS thermal comfort was 53.3 (± 15.7) in SHB and 52.9 (± 12.3) in FAB patients. No difference in complication rate was found. CONCLUSIONS: In this study neither kind of the warming blanket prevented perioperative hypothermia. Although a difference of 0.2°C was found between both groups at the end of TKR/THR surgery, this is most probably not clinically relevant. Complication rate in both groups was the same.

Conversion from knee arthrodesis to arthroplasty: systematic review.

PURPOSE: Arthrodesis (AD) of the knee reduces pain and provides stability, but has severe functional and social limitations. There has been ample discussion on the value of a conversion of an AD to a total knee arthroplasty (TKA). The aim of this study was to perform a review and meta-analysis of the current literature on conversion of an AD to TKA and assess clinical outcome, complication rate, surgical technique and overall patient-related outcome measures. METHODS: PubMed, Embase, Web of Science, Cochrane, CENTRAL, CINAHL, Academic Search Premier, ScienceDirect and searching by hand for papers on conversion of AD of the knee to TKA. Two reviewers independently reviewed all titles and abstracts, and extracted the available data. Study eligibility criteria were: conversion of knee AD to TKA, five cases or more and non-oncology patients. Data consisted of study characteristics, patient demographics, clinical outcome and complications. Additionally, details on surgical technique were reviewed. RESULTS: Of the 866 unique references identified, six papers were included for further analyses, comprising a total of 123 knees with conversion of AD of the knee to TKA. Mean gain of knee flexion was 80 degrees and the mean HSS score improved with 20 points. A complicated postoperative course was found in 65 % of all cases. The most frequent complication was skin necrosis (25 %), followed by arthrofibrosis (13 %), infection (11 %) and revision (11 %). Major complications such as refusion, amputation and death occurred in less than 5 % of all cases. DISCUSSION: The majority of the papers consisted of small case series of moderate methodological quality, resulting in 123 included knees. Further series are necessary to draw definitive conclusions. CONCLUSIONS: This is the first systematic review and meta-analysis on conversion of a knee arthrodesis to TKA. Good clinical results can be expected after conversion, albeit at a high risk of postoperative complications.

Similar outcome after retention or sacrifice of the posterior cruciate ligament in total knee arthroplasty.

BACKGROUND AND PURPOSE: To retain or to sacrifice the posterior cruciate ligament (PCL) in total knee arthroplasty (TKA) remains a matter of discussion. In this systematic review, we wanted to find differences in functional and clinical outcome between the 2 methods. METHODS: We conducted a systematic review and meta-analysis including all randomized controlled trials (RCTs) and quasi-RCTs that have compared PCL retention with PCL sacrifice in TKA with a minimum of 1-year follow-up. Primary outcome was range of motion. Secondary outcomes were knee pain and clinical scoring systems that were preferably validated. Quality of evidence was graded using the GRADE approach. All outcomes available for data pooling were used for meta-analysis. RESULTS: 20 studies involving 1,877 patients and 2,347 knees were included. In meta-analysis, the postoperative flexion angle had a mean difference of 2 degrees (95% CI: 0.23-4.0; p = 0.03) and the KSS functional score was 2.4 points higher in favor of PCL sacrifice (95% CI: 0.41-4.3; p = 0.02). There were no statistically significant differences regarding other measured clinical outcomes such as WOMAC, KSS pain, clinical and overall score, HSS score, SF-12, radiolucencies, femoro-tibial angle, and tibial slope. The quality of the studies varied considerably. Risk of bias in most studies was unclear; 5 were judged to have a low risk of bias and 5 to have a high risk of bias. INTERPRETATION: We found no clinically relevant differences between retention and sacrifice of the PCL in TKA, in terms of functional and clinical outcomes. The quality of the studies ranged from moderate to low. Based on the current evidence, no recommendation can be made as to whether to retain or to sacrifice the PCL.

Recovery of TES-MEPs during surgical decompression of the spine: a case series of eight patients.

PURPOSE: This study aimed to illustrate the recovery of transcranial electrical stimulation motor evoked potentials during surgical decompression of the spinal cord in patients with impaired motor function preoperatively. Specific attention was paid to the duration of neurologic symptoms before surgery and the postoperative clinical recovery. METHODS: A case series of eight patients was selected from a cohort of 74 patients that underwent spine surgery. The selected patients initially had low or absent transcranial electrical stimulation motor evoked potentials followed by a significant increase after surgical decompression of the spinal cord. RESULTS: A significant intraoperative increase in amplitude of motor evoked potentials was detected after decompression of the spinal cord or cauda equina in patients suffering from spinal canal stenosis (n = 2), extradural meningioma (n = 3), or a herniated nucleus polposus (n = 3). This was related to an enhanced neurologic outcome only if patients (n = 6) had a short onset (less than ½ year) of neurologic impairment before surgery. CONCLUSIONS: In patients with a short onset of neurologic impairment because of compression of the spinal cord or caudal fibers, an intraoperative recovery of transcranial electrical stimulation motor evoked potentials can indicate an improvement of motor function postoperatively. Therefore, transcranial electrical stimulation motor evoked potentials can be considered as a useful tool to the surgeon to monitor the quality of decompression of the spinal cord.

Retention versus sacrifice of the posterior cruciate ligament in total knee arthroplasty for treating osteoarthritis.

BACKGROUND: The functional and clinical basis on which to choose whether or not to retain the posterior cruciate ligament during total knee arthroplasty surgery remained unclear after a Cochrane systematic review and meta-analysis in 2005, which contained eight clinical trials. Several new trials have been conducted since then. Hence, an update of the review was performed. OBJECTIVES: Our aim was to assess the benefits and harms of retention compared to sacrifice of the posterior cruciate ligament in total knee arthroplasty in patients with osteoarthritis of the knee. SEARCH METHODS: An extensive search was conducted in CENTRAL, MEDLINE (PubMed), EMBASE, Web of Science, CINAHL, Academic Search Premier, Current Contents Connect and Science Direct. All databases were searched, without any limitations, up to 6 December 2012. References of the articles were checked and citation tracking was performed. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials comparing retention with sacrifice of the posterior cruciate ligament in primary total knee arthroplasty in patients with osteoarthritis of the knee. DATA COLLECTION AND ANALYSIS: Data were collected with a pre-developed form. Risk of bias was assessed independently by two authors (WV, LB). The level of evidence was graded using the GRADE approach. Meta-analysis was performed by pooling the results of the selected studies, when possible. Subgroup analyses were performed for posterior cruciate ligament retention versus sacrifice using the same total knee arthroplasty design, and for studies using a posterior cruciate ligament retaining or posterior stabilised design, and when sufficient studies were available subgroup analyses were performed for the same brand. MAIN RESULTS: Seventeen randomised controlled trials (with 1810 patients and 2206 knees) were found, described in 18 articles. Ten of these were new studies compared to the previous Cochrane Review. One study from the original Cochrane review was excluded. Most new studies compared a posterior cruciate ligament retaining design with a posterior stabilised design, in which the posterior cruciate ligament is sacrificed (a posterior stabilised design has an insert with a central post which can engage on a femoral cam during flexion).The quality of evidence (graded with the GRADE approach) and the risk of bias were highly variable, ranging from moderate to low quality evidence and with unclear or low risk of bias for most domains, respectively.The performance outcome 'range of motion' was 2.4 ° higher in favour of posterior cruciate ligament sacrifice (118.3 ° versus 115.9 °; 95% confidence interval (CI) of the difference 0.13 to 4.67; P = 0.04), however the results were heterogeneous. On the item 'knee pain' as experienced by patients, meta-analysis could be performed on the Knee Society knee pain score; this score was 48.3 in both groups, yielding no difference between the groups. Implant survival rate could not be meta-analysed adequately since randomised controlled trials lack the longer term follow-up in order to evaluate implant survival. A total of four revisions in the cruciate-retention and four revisions in the cruciate-sacrifice group were found. The well-validated Western Ontario and McMaster Universities osteoarthritis index (WOMAC) total score was not statistically significantly different between the groups (16.6 points for cruciate-retention versus 15.0 points for cruciate-sacrifice). One study reported a patient satisfaction grade (7.7 points for cruciate-retention versus 7.9 points for cruciate-sacrifice on a scale from 0 to 10, 10 being completely satisfied) which did not differ statistically significantly. Complications were distributed equally between both groups. Only one study reported several re-operations other than revision surgery; that is patella luxations, surgical manipulation because of impaired flexion.The mean functional Knee Society Score was 2.3 points higher (81.2 versus 79.0 points; 95% CI of the difference 0.37 to 4.26; P = 0.02) in the posterior cruciate ligament sacrificing group. Results from the outcome Knee Society functional score were homogeneous. All other outcome measures (extension angle, knee pain, adverse effects, clinical questionnaire scores, Knee Society clinical scores, radiological rollback, radiolucencies, femorotibial angle and tibial slope) showed no statistically significant differences between the groups. In the subgroup analyses that allowed pooling of the results of the different studies, no homogeneous statistically significant differences were identified. AUTHORS' CONCLUSIONS: The methodological quality and the quality of reporting of the studies were highly variable. With respect to range of motion, pain, clinical, and radiological outcomes, no clinically relevant differences were found between total knee arthroplasty with retention or sacrifice of the posterior cruciate ligament. Two statistically significant differences were found; range of motion was 2.4 ° higher in the posterior cruciate ligament sacrificing group, however results were heterogeneous; and the mean functional Knee Society Score was 2.3 points higher in the posterior cruciate ligament sacrificing group. These differences are clinically not relevant.

All-polyethylene tibial components are equal to metal-backed components: systematic review and meta-regression.

BACKGROUND: Less than 1% of all primary TKAs are performed with an all-polyethylene tibial component, although recent studies indicate all-polyethylene tibial components are equal to or better than metal-backed ones. QUESTIONS/PURPOSES: We asked whether the metal-backed tibial component was clinically superior to the all-polyethylene tibial component in primary TKAs regarding revision rates and clinical functioning, and which modifying variables affected the revision rate. METHODS: We systematically reviewed the literature for clinical studies comparing all-polyethylene and metal-backed tibial components used in primary TKAs in terms of revision rates, clinical scores, and radiologic parameters including radiostereometric analysis (RSA). Meta-regression techniques were used to explore factors modifying the observed effect. Our search yielded 1557 unique references of which 26 articles were included, comprising more than 12,500 TKAs with 231 revisions for any reason. RESULTS: Meta-analysis showed no differences between the all-polyethylene and metal-backed components except for higher migration of the metal-backed components. Meta-regression showed strong evidence that the all-polyethylene design has improved with time compared with the metal-backed design. CONCLUSIONS: The all-polyethylene components were equivalent to metal-backed components regarding revision rates and clinical scores. The all-polyethylene components had better fixation (RSA) than the metal-backed components. The belief that metal-backed components are better than all-polyethylene ones seems to be based on studies from earlier TKAs. This might no longer be true for modern TKAs. LEVEL OF EVIDENCE: Level II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Total joint replacement in the past does not relate to a deteriorated functional level and health status in the oldest old.

Total hip or knee replacement is effective in improving joint function, quality of life, and pain reduction. The oldest old population with joint replacements (TJR) is underrepresented in current literature. We compared health-related and functional characteristics of oldest olds with and without TJR. Participants (aged 85 years) were divided into a group with and without TJR. Comorbidity, physical and joint functioning, daily living activities, quality of life, and mortality were recorded. Thirty-eight of 599 participants (6.3%) received a TJR in the past. Participants with a TJR had slightly less comorbidities, walked slower (P = 0.006), and complained more about hip-pain (P = 0.007). Mortality of those with a TJR was lower during the first 8-year followup (P = 0.04). All other characteristics were comparable between groups. We conclude that subjects with a TJR performed equally well, besides showing a lower gait speed and a higher frequency of hip-pain. Except for the lower gaitspeed, having a TJR is not associated with poorer health.

[Unexpected back pain in the elderly ankylosing spondylitis patient]. / Onverwachte rugpijn bij de oudere bechterewpatiënt.

A 63-year-old man with ankylosing spondylitis (AS) presented with persistent pain in his back after minor trauma. Radiographs revealed no acute pathology. Six weeks later an MRI scan was performed which showed a vertebral fracture at level Tiii with kyphotic deformity. Another 63-year-old male AS patient presented with back pain after minor trauma 10 days before presentation. At plain radiology a vertebral fracture of Tx was discovered. A third patient, an 83-year-old male AS patient complained about back pain after minor trauma; CT imaging revealed a Tx vertebral fracture. All three patients underwent surgical fixation and were discharged without major complications. In principle, an older patient with an established AS complaining of back pain must be regarded as having a fracture of the vertebral column until the contrary is proven, even in the absence of any recent history of trauma. This strategy can prevent major complication in these patients.

Prevalence of vertebral pars defects (spondylolysis) in a population with osteogenesis imperfecta.

STUDY DESIGN: We performed a retrospective study of spinal roentgenograms of a large cohort of patients suffering from osteogenesis imperfecta. OBJECTIVE: To determine the prevalence of vertebral pars defects (spondylolysis) in patients with osteogenesis imperfecta. SUMMARY OF BACKGROUND DATA: Patients suffering from osteogenesis imperfecta are known to be prone to pathologic fractures. Pathologic fractures due to microtraumas, repetitive activities, and posture acting together on a congenitally weakened pars interarticularis may lead to vertebral pars defects. The prevalence of vertebral pars defects in patients with osteogenesis imperfecta has never been studied before to our knowledge. METHODS: We performed a retrospective study of posterior-anterior and lateral, standing, roentgenograms of the spine of patients with osteogenesis imperfecta for the occurrence of vertebral pars interarticularis defects. RESULTS: The patients (5.3%) in our series showed vertebral pars defects, this is not significantly different from the prevalence of vertebral pars defects in the general population. CONCLUSION: 5.3% of the patients with osteogenesis imperfecta showed vertebral pars defects, this does not differ significantly from the occurrence in the general population.

Myeloid sarcoma presenting as a recurrent, multifocal nerve root entrapment syndrome.

BACKGROUND: Myeloid sarcoma is an extramedullary manifestation of haematologic malignancy, most commonly acute myeloid leukemia (AML), which can cause neurological symptoms. CASE DESCRIPTION: A 45-year-old male with a history of AML presented with a lumbosacral nerve root entrapment syndrome followed by cauda equina compression, but without systemic signs of AML recurrence. MRI showed a mass compressing the spinal cord at level L5-S2. After surgically removing the tumour pathologic examination yielded a myeloid sarcoma. Combined chemotherapy and radiation therapy followed. Five months later the patient developed a thoracal (Th10-Th11) radiculopathy due to a relapse of the myeloid sarcoma, followed by C8-Th1-radiculopathy caused by leptomeningeal spread. CONCLUSION: This case forms the first description of recurrent, multifocal and progressive radiculopathy due to myeloid sarcoma. This diagnosis should be considered in patients with radiculopathy with previous haematological malignancy and/or signs or symptoms of such disease; the absence of systemic disease activity does not rule out myeloid sarcoma.