Joris J. W. Ploegmakers

Comparative anatomical dimensions of the complete human and porcine spine

New spinal implants and surgical procedures are often tested pre-clinically on human cadaver spines. However, the availability of fresh frozen human cadaver material is very limited and alternative animal spines are more easily available in all desired age groups, and have more uniform geometrical and biomechanical properties. The porcine spine is said to be the most representative model for the human spine but a complete anatomical comparison is lacking. The goal of this descriptive study was to compare the anatomical dimensions of the cervical, thoracic, and lumbar vertebrae of the human and porcine spine in order to determine whether the porcine spine can be a representative model for the human spine. CT scans were made of 6 human and 6 porcine spines, and 16 anatomical dimensions were measured per individual vertebrae. Comparisons were made for the absolute values of the dimensions, for the patterns of the dimensions within four spinal regions, and normalised values of the dimensions within each individual vertebra. Similarities were found in vertebral body height, shape of the end-plates, shape of the spinal canal, and pedicle size. Furthermore, regional trends were comparable for all dimensions, except for spinal canal depth and spinous processus angle. The size of the end-plates increased more caudally in the human spine. Relating the dimensions to the size of the vertebral body, similarities were found in the size of the spinal canal, the transverse processus length, and size of the pedicles. Taking scaling differences into account, it is believed that the porcine spine can be a representative anatomical model for the human spine in specific research questions.

Grip strength is strongly associated with height, weight and gender in childhood: a cross sectional study of 2241 children and adolescents providing reference values

QUESTION What are reference values for grip strength in children and adolescents based on a large and heterogeneous study population? What is the association of grip strength with age, gender, weight, and height in this population? DESIGN Cross-sectional study. PARTICIPANTS Participants were recruited from schools in the northern provinces of the Netherlands. The study included healthy children and adolescents ranging in age from 4 to 15 years. OUTCOME MEASURES All children had their height (cm) and weight (kg) measured and were allowed a total of four attempts using the Jamar hand dynamometer: twice with each hand. Grip strength scores (kg) were recorded for the dominant and non-dominant hands. RESULTS The study population comprised 2241 children and adolescents. Reference values for both genders are provided according to age and dominance. Grip strength shows a linear and parallel progression for both genders until the age of 11 or 12, after which grip strength development shows an acceleration that is more prominent in boys. CONCLUSION There is a significant difference in grip strength with each ascending year of age in favour of the older group, as well as a trend for boys to be stronger than girls in all age groups between 4 and 15 years. Weight and especially height have a strong association with grip strength in children.

Local Treatment with Adjuvant Therapy for Central Atypical Cartilaginous Tumors in the Long Bones: Analysis of Outcome and Complications in One Hundred and Eight Patients with a Minimum Follow-up of Two Years

BACKGROUND A central atypical cartilaginous tumor (ACT)--formerly known as chondrosarcoma grade 1 (CS1)--is a tumor of intermediate-type malignancy, often treated with surgery. The extent of surgery remains controversial, as some advocate resection and others favor local treatment by curettage. Because of the low prevalence of ACT/CS1, the available data are limited and generally not uniform. The purpose of this study was to present the outcome for a large cohort of patients with ACT/CS1 in the long bones who were treated with curettage and adjuvant phenolization and followed for a minimum of two years according to national guidelines. METHODS A retrospective study was designed to analyze data from 108 patients treated for central ACT/CS1 in the long bones between 2006 and 2012. All patients were treated with curettage and adjuvant phenolization, and defects were filled with polymethylmethacrylate, bone graft, or bone substitutes. The primary end point was local recurrence or residual tumor. Secondary end points included the type and rate of complications and reoperations. RESULTS All patients were free from local recurrence at a mean follow-up of 48.7 months (range, 24.3 to 97.5 months). Residual tumor was suspected in five patients, leading to a 95.4% disease-free survival rate. A fracture occurred in eleven patients (10.2%). Other complications were osseous penetration during the surgery (two patients), wound infection (one patient), arthrofibrosis (one patient), and skin necrosis (one patient). Tumor volume was related neither to the risk of fracture nor to the occurrence of residual tumor. CONCLUSIONS In our experience, curettage of ACT/CS1 in the long bones with adjuvant phenolization is safe, even with large tumors of up to 100 cm(3). Most worrisome is the risk of fracture, which occurred in 10.2% of our patients. Considering the relatively mild behavior of ACT/CS1, less aggressive treatment, by observation or by minimally invasive surgery, could be the next step that should be evaluated prospectively.

Computer-assisted surgery in orthopedic oncology: Technique, indications, and a descriptive study of 130 cases

Background and purpose — In orthopedic oncology, computer-assisted surgery (CAS) can be considered an alternative to fluoroscopy and direct measurement for orientation, planning, and margin control. However, only small case series reporting specific applications have been published. We therefore describe possible applications of CAS and report preliminary results in 130 procedures. Patients and methods — We conducted a retrospective cohort study of all oncological CAS procedures in a single institution from November 2006 to March 2013. Mean follow-up time was 32 months. We categorized and analyzed 130 procedures for clinical parameters. The categories were image-based intralesional treatment, image-based resection, image-based resection and reconstruction, and imageless resection and reconstruction. Results — Application to intralesional treatment showed 1 inadequate curettage and 1 (other) recurrence in 63 cases. Image-based resections in 42 cases showed 40 R0 margins; 16 in 17 pelvic resections. Image-based reconstruction facilitated graft creation with a mean reconstruction accuracy of 0.9 mm in one case. Imageless CAS was helpful in resection planning and length- and joint line reconstruction for tumor prostheses. Interpretation — CAS is a promising new development. Preliminary results show a high number of R0 resections and low short-term recurrence rates for curettage.

The presentation, treatment and outcome of periosteal chondrosarcoma in the Netherlands

In this case study, we describe the clinical presentation and treatment of 36 patients with periosteal chondrosarcoma collected over a 59-year period by the archive of the Netherlands Committee on Bone Tumours. The demographics, clinical presentation, radiological features, treatment and follow-up are presented with the size, location, the histological grading of the tumour and the survival. We found a slight predominance of men (61%), and a predilection for the distal femur (33%) and proximal humerus (33%). The metaphysis was the most common site (47%) and the most common presentation was with pain (44%). Half the tumours were classified histologically as grade 1. Pulmonary metastases were reported in one patient after an intra-lesional resection. A second patient died from local recurrence and possible pulmonary and skin metastases after an incomplete resection. It is clearly important to make the diagnosis appropriately because an incomplete resection may result in local recurrence and metastatic spread. Staging for metastatic disease is recommended in grade II or III lesions. These patients should be managed with a contrast-enhanced MRI of the tumour and histological confirmation by biopsy, followed by en-bloc excision.

Synovial calprotectin: a potential biomarker to exclude a prosthetic joint infection

Aims Recently, several synovial biomarkers have been introduced into the algorithm for the diagnosis of a prosthetic joint infection (PJI). Alpha defensin is a promising biomarker, with a high sensitivity and specificity, but it is expensive. Calprotectin is a protein that is present in the cytoplasm of neutrophils, is released upon neutrophil activation and exhibits antimicrobial activity. Our aim, in this study, was to determine the diagnostic potential of synovial calprotectin in the diagnosis of a PJI. Patients and Methods In this pilot study, we prospectively collected synovial fluid from the hip, knee, shoulder and elbow of 19 patients with a proven PJI and from a control group of 42 patients who underwent revision surgery without a PJI. PJI was diagnosed according to the current diagnostic criteria of the Musculoskeletal Infection Society. Synovial fluid was centrifuged and the supernatant was used to measure the level of calprotectin after applying a lateral flow immunoassay. Results The median synovial calprotectin level was 991 mg/L (interquartile range (IQR) 154 to 1787) in those with a PJI and 11 mg/L (IQR 3 to 29) in the control group (p < 0.0001). Using a cutoff value of 50 mg/L, this level showed an excellent diagnostic accuracy, with an area under the curve of 0.94. The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) was 89%, 90%, 81% and 95% respectively. The NPV was 97% in the nine patients with a chronic PJI. Conclusion Synovial calprotectin may be a valuable biomarker in the diagnosis of a PJI, especially in the exclusion of an infection. With a lateral flow immunoassay, a relatively rapid quantitative diagnosis can be made. The measurement is cheap and is easy to use.

The Influence of Hand Preference on Grip Strength in Children and Adolescents; A Cross-Sectional Study of 2284 Children and Adolescents.

Introduction In adults the preferred hand is often considered to be around 10% stronger than the non-preferred hand. Whether the same is true for children and adolescents remains unclear. The objective of this study is therefore to determine whether there is a difference in grip strength between the preferred and non-preferred hand in developing children, to establish whether this difference is similar for children of a different gender or hand preference, and whether there is a difference in grip strength of the preferred hand of left-preferent (LP) and right-preferent (RP) children. Design Cross-sectional study. Participants Participants were recruited from schools in the northern provinces of the Netherlands. The study included healthy children and adolescents in the age range of 4–17 years. Outcome Measures Each child was allowed a total of four attempts using the JAMAR hand dynamometer, two attempts with each hand. All individual attempts were scored. Hand preference was determined by asking which hand was used to write, or in the case of 4- and 5-year-olds, which hand was used to draw a shape. Results The study population comprised 2284 children and adolescents. RP boys and girls scored significantly higher with their preferred hand, the difference amounting to 9.5 and 10.1% respectively. LP girls scored significantly higher with their preferred hand, but this difference was only 3.0%. For LP boys no significant difference was found in favor of either hand. LP children score higher with the non-preferred hand and tie scores on both hands more often than RP children. Conclusion The 10% rule of hand preference is applicable to RP children ranging in age between 4 and 17 years, but not to LP children. In contrast to LP boys, LP girls are generally significantly stronger with their preferred hand.

Delay in Diagnosis and Its Effect on Clinical Outcome in High‐grade Sarcoma of Bone: A Referral Oncological Centre Study

To investigate delay in diagnosis by both patients and doctors, and to evaluate its effect on outcomes of high‐grade sarcoma of bone in a single‐referral oncological center.

Predicting Failure in Early Acute Prosthetic Joint Infection Treated With Debridement, Antibiotics, and Implant Retention: External Validation of the KLIC Score

BACKGROUND Debridement, antibiotics, and implant retention (DAIR) is a widely used treatment modality for early acute prosthetic joint infection (PJI). A preoperative risk score was previously designed for predicting DAIR failure, consisting of chronic renal failure (K), liver cirrhosis (L), index surgery (I), cemented prosthesis (C), and C-reactive protein >115 mg/L (KLIC). The aim of this study was to validate the KLIC score in an external cohort. METHODS We retrospectively evaluated patients with early acute PJI treated with DAIR between 2006 and 2016 in 3 Dutch hospitals. Early acute PJI was defined as <21 days of symptoms and DAIR performed within 90 days after index surgery. Failure was defined as the need for (1) second DAIR, (2) implant removal, (3) suppressive antimicrobial treatment, or (4) infection-related death within 60 days after debridement. RESULTS A total of 386 patients were included. Failure occurred in 148 patients (38.3%). Patients with KLIC scores of ≤2, 2.5-3.5, 4-5, 5.5-6.5, and ≥7 had failure rates of 27.9%, 37.1%, 49.3%, 54.5%, and 85.7%, respectively (P < .001). The receiver-operating characteristic curve showed an area under the curve of 0.64 (95% confidence interval 0.59-0.69). A KLIC score higher than 6 points showed a specificity of 97.9%. CONCLUSION The KLIC score is a relatively good preoperative risk score for DAIR failure in patients with early acute PJI and appears to be most useful in clinical practice for patients with low or high KLIC scores.

The push-through total femoral prosthesis offers a functional alternative to total femoral replacement: a case series

PurposeOncologic resections or complications of segmental femoral prostheses can result in severe bone loss of the femur for which a total femoral prosthesis (TFP) is required. This study assesses whether the loss of stability and function caused by the loss of muscle attachments can be improved by using a push-through total femoral endoprosthesis (PTTF), because it saves parts of the femur and its muscle attachments.MethodsIn this retrospective case series, ten patients aged 25–77 (mean 54) who received a PTTF between 2005 and 2014 were included for baseline, complications and survival analysis with a mean follow-up of 5.3 (1.1–9.6) years. Functional outcome was assessed in six patients using the Musculoskeletal Tumor Society (MSTS) score, WHO performance scale, Toronto Extremity Salvage Score (TESS), SF36, EQ-5D, NRS pain score, fatigue score and satisfaction score.ResultsThe mean MSTS score was 64% (23–93%). Five patients had a WHO performance scale of 1, one patient of 3. Mean TESS was 69% (13–90%). SF36 was most notably limited by physical functioning (mean 48), vitality (68) and general health (67). NRS score was 1.9, 1.8 and 8.3 for pain, fatigue and satisfaction, respectively. There were four failures: two infections (one resulting in amputation and one in a minor revision) and two mechanical failures (which required one revision to a TFP and one minor revision). Patient survival was 100%, limb survival 90%, and prosthesis survival 80%.ConclusionThe push-through total femoral endoprosthesis allows preservation of muscle attachments and offers a good alternative to total femoral prostheses.