Sagittal balance parameters in achondroplasia.

Introduction: Lumbar spinal stenosis (LSS) is the main problem for adult achondroplasia (Ach). Sagittal imbalance of the spine may play a role in LSS causing neurogenic claudication in Ach patients. Research question: The purpose of this study is to describe the sagittal balance parameters in Ach patients. Methods: A single-centre retrospective study of Ach patients that visited the Neurosurgery outpatient clinic of the Leiden University Medical Centre (LUMC) between 2019 and 2022 was performed. We defined sagittal imbalance by a C7 sagittal vertical axis (SVA) of more than 10 mm. Results: There were 13 patients with a spinal sagittal imbalance and 15 patients with a balanced spine. In both groups, the sacral slope (SS) was comparable (45.0° and 49.0°, p = 0.305), but exceeding the mean SS in non achondroplasts (38.0°). Lumbar lordosis (LL) was more pronounced in the balanced group (55.5° versus 41.7°, p = 0.019), and positively correlated to SS in contrast to the absence of a correlation in the imbalanced group. Thoracolumbar kyphosis (TLK) was increased comparably in both groups (19.6° and 24.6°), and far exceeding the TLK in non achondroplasts (circa 0°), and in both groups negatively correlated with the LL, although not enough to compensate for the smaller LL in the imbalanced group. Conclusion: Only if the LL compensates for both a larger SS and TLK, the Ach spine can maintain sagittal balance. An explanation for the current data can be the failure of the lumbar spine to give sufficient lordosis due to degenerative processes.

The risk of delayed spinal cord injury in pediatric spinal deformity surgery.

Delayed spinal cord injury (SCI) hours or days after surgery, with uneventful monitoring and initial normal postoperative neurological examination, is a rare complication. Based on anecdotal evidence, the risk of delayed spinal cord injury might be higher than previously assumed. Therefore the aim of this study was to determine the risk of delayed SCI after pediatric spinal deformity surgery between 2013-2019 in the Netherlands. The total number of pediatric spinal deformity surgeries performed for scoliosis or kyphosis between 2013-2019 was obtained from the Dutch National Registration of Hospital Care. All eleven Dutch hospitals that perform pediatric spinal deformity surgery were contacted for occurrence of delayed SCI. From the identified patients with delayed SCI, the following data were collected: patient characteristics, details about the SCI, the surgical procedure, management and degree of improvement.2884 pediatric deformity surgeries were identified between 2013-2019. Seven patients (0.24%) with delayed SCI were reported: 3 idiopathic, 2 neuromuscular (including 1 kypho-scoliosis) and 2 syndromic scoliosis. The risk of delayed SCI after pediatric deformity surgery was 1:595 in idiopathic scoliosis, 1:214 in syndromic scoliosis, 1:201 in neuromuscular scoliosis. All seven patients had a documented normal neurological examination in the first postoperative period; neurological deficits were first diagnosed at a median 16h (range 2.5-40) after surgery. The risk of delayed SCI after pediatric deformity surgery is higher than previously reported, especially in patients with non-idiopathic scoliosis. Regular postoperative testing for late neurologic deficit should be performed for timely diagnosis and management of this devastating complication.

CT analysis of the posterior anatomical landmarks of the scoliotic spine.

AIM: To use computed tomography (CT) to assess the validity and reliability of the posterior landmarks, spinous processes (SP), transverse processes (TP), and centre of lamina (COL), as compared to the Cobb angle to assess the curve severity and progression of adolescent idiopathic scoliosis (AIS). MATERIALS AND METHODS: A consecutive series of CT examinations of severe AIS patients were included retrospectively. SP, TP, and COL angles were measured for all curves and compared to the Cobb angle. RESULTS: One hundred and five patients were included. The mean Cobb versus SP, TP, and COL angles were, 54° versus 37°, 49°, and 51° in the thoracic curves and 34° versus 26°, 31°, and 34° in the (thoraco)lumbar curves. Intraclass correlation coefficient values for intra-rater measurements of the SP, TP, and COL angles were 0.93, 0.97, and 0.95 and 0.70, 0.90, and 0.88 for inter-rater measurements. The correlations between the Cobb angle and SP, TP, and COL angles in thoracic and (thoraco)lumbar curves were 0.79 and 0.66, 0.87 and 0.84, and 0.80 and 0.70. CONCLUSIONS: The posterior spinal landmarks can be used for assessment of scoliosis severity in AIS; however, they show a systematic underestimation, but a strong correlation with the coronal Cobb angle. TP and COL angles had the highest validity.

Semi-automatic method for pre-surgery scoliosis classification on X-ray images using Bending Asymmetry Index.

PURPOSE: Bending Asymmetry Index (BAI) has been proposed to characterize the types of scoliotic curve in three-dimensional ultrasound imaging. Scolioscan has demonstrated its validity and reliability in scoliosis assessment with manual assessment-based X-ray imaging. The objective of this study is to investigate the ultrasound-derived BAI method to X-ray imaging of scoliosis, with supplementary information provided for the pre-surgery planning. METHODS: About 30 pre-surgery scoliosis subjects (9 males and 21 females; Cobb: 50.9 ± 19.7°, range 18°-115°) were investigated retrospectively. Each subject underwent three-posture X-ray scanning supine on a plain mattress on the same day. BAI is an indicator to distinguish structural or non-structural curves through the spine flexibility information obtained from lateral bending spinal profiles. BAI was calculated semi-automatically with manual annotation of vertebral centroids and pelvis level inclination adjustment. BAI classification was validated with the scoliotic curve type and traditional Lenke classification using side-bending Cobb angle measurement (S-Cobb). RESULTS: 82 curves from 30 pre-surgery scoliosis patients were included. The correlation coefficient was R2 = 0.730 (p < 0.05) between BAI and S-Cobb. In terms of scoliotic curve type classification, all curves were correctly classified; out of 30 subjects, 1 case was confirmed as misclassified when applying to Lenke classification earlier, thus has been adjusted. CONCLUSION: BAI method has demonstrated its inter-modality versatility in X-ray imaging application. The curve type classification and the pre-surgery Lenke classification both indicated promising performances upon the exploratory dataset. A fully-automated of BAI measurement is surely an interesting direction to continue our endeavor. Deep learning on the vertebral-level segmentation should be involved in further study.

Current Evidence for Spinopelvic Characteristics Influencing Total Hip Arthroplasty Dislocation Risk.

BACKGROUND: Decreased pelvic mobility and pelvic retroversion may result from spinal degeneration and lead to changes in the orientation of the acetabular implant after total hip arthroplasty (THA). While multiple patient and surgery-related factors contribute to THA dislocations, there is increasing evidence that sagittal spinopelvic dynamics are relevant for THA stability. The aim of this systematic review was to assess the relationship between previously described sagittal spinopelvic characteristics and implant dislocations after primary THA. METHODS: A comprehensive literature search in the PubMed and Embase databases was conducted for studies reporting on spinopelvic morphology, alignment, pathology, or surgery and THA dislocations. Risk of bias was assessed using the MINORS criteria. Because of high heterogeneity in study methodology, a synthesis of best evidence was performed. Odds ratios (ORs), relative risks (RRs), and effect sizes (g) were calculated. RESULTS: Fifteen studies (1,007,900 THAs) with quality scores of 15 to 23 out of 24 were included. Nine different spinopelvic alignment parameters (8 studies, g = 0.14 to 2.02), spinal pathology (2 studies, OR = 1.9 to 29.2), and previous spinal fusion surgery (8 studies, OR = 1.59 to 23.7, RR = 3.0) were found to be related to THA dislocation. Conflicting results were found for another sagittal pelvic morphology parameter, pelvic incidence. CONCLUSIONS: Several sagittal spinopelvic patient characteristics were found to be related to THA dislocation, and the associated risks were greater than for other patient and surgery-related factors. Future research is needed to determine which of those characteristics and parameters should be taken into account in patients undergoing primary THA. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Variations in the sagittal plane precede the development of scoliosis: a proof of concept.

Idiopathic scoliosis in man is believed to be related to the unique human sagittal profile. Patients with a thoracic scoliosis have a longer, more proximal, posteriorly inclined segment of the spine as compared to lumbar scoliosis and controls, whereas patients with a lumbar scoliosis have a more caudal, shorter and steeper posteriorly inclined segment. In 22q11.2 deletion syndrome, half of the patients develop a scoliosis that is very similar to idiopathic scoliosis and may serve as a model for the general population. In our center, all patients with 22q11.2 deletion syndrome older than 6 years receive standardized radiographic spine imaging every 2 years to screen for scoliosis. In this prospective proof-of-principle study the goal was to determine whether there are differences in sagittal alignment between patients that develop scoliosis vs. controls before the onset of scoliosis, and obtain data to perform a power calculation for future studies. To capture the sagittal shape of the spine into one risk factor for development for scoliosis, we combined relative length and magnitude of dorsal inclination into a new parameter: the posterior inclined triangle surface (PITS). We included 31 patients with initially straight spines, five developed a thoracic scoliosis and seven developed a (thoraco)lumbar scoliosis after a mean follow-up of 3.4 years. The PITS was considerably higher in the group that developed scoliosis as compared to the controls (59 vs 43). Based on this pilot study, we have identified a potential overall sagittal profile risk parameter for the development of idiopathic scoliosis.

Anterior lengthening in scoliosis occurs only in the disc and is similar in different types of scoliosis.

Relative anterior spinal overgrowth (RASO) was proposed as a generalized growth disturbance and a potential initiator of adolescent idiopathic scoliosis (AIS). However, anterior lengthening was also observed in neuromuscular (NM) scoliosis, was shown to be restricted to the apical areas and to be located in the intervertebral discs, not in the bone. In this study the goal was to determine if other scoliotic curves of known origin exhibit the similar mechanism of anterior lengthening without changes in the vertebral body. Therefore CT-scans of 18 patients in whom a short segment congenital malformation had led to a long thoracic compensatory curve without bony abnormality were included. Of each vertebral body and intervertebral disc in the compensatory curve, the anterior and posterior length was measured on CT-scans in the exact mid-sagittal plane, corrected for deformity in all three planes. The total AP% of the compensatory curve in congenital scoliosis showed a lordosis (+1.8%) that differed from the kyphosis in non-scoliotic controls (-3.0%; p<0.001), and was comparable to AIS (+1.2%) and NM scoliosis (+0.5%). This anterior lengthening was not located in the bone; the vertebral body AP% showed a kyphosis (-3.2%), similar to non-scoliotic controls (-3.4%), as well as AIS (-2.5%) and NM scoliosis (-4.5%; p=1.000). However, the disc AP% showed a lordosis (+24.3%), which sharply contrasts to the kyphotic discs of controls (-1.5%; p<0.001), but was similar to AIS (+17.5%) and NM scoliosis (+20.5%). The results demonstrate that anterior lengthening is part of the three-dimensional deformity in different types of scoliosis and is exclusively located in the intervertebral discs. The bony vertebral bodies maintain their kyphotic shape, which indicates that there is no active bony overgrowth. Anterior lengthening appears to be a passive result of any scoliotic deformity, rather than being related to the specific cause of AIS.

Spring distraction system to correct early onset scoliosis: 2 year follow-up results from 24 patients.

Current surgical treatment options for Early Onset Scoliosis (EOS), with distraction- or growth-guidance systems, show limited growth and high complication rates. We developed the Spring Distraction System (SDS), which does not have to be periodically lengthened and which provides continuous corrective force to stimulate spinal growth. This study aimed to assess curve correction and maintenance, spinal growth, and complication rate following SDS treatment. All primary- and revision patients (conversion from failed other systems) with SDS and ≥2 years follow-up were included. Outcome measures were coronal Cobb angle, sagittal parameters, spinal length measurements and complications and re-operations. Radiographic parameters were compared pre-operatively, post-operatively and at latest follow-up. Spinal length increase was expressed as mm/year. Twenty-four skeletally immature EOS patients (18 primary and 6 revision cases) were included. There were 5 idiopathic, 7 congenital, 3 syndromic and 9 neuromuscular EOS patients. Mean age at implantation was 9.1 years (primary: 8.4; conversion: 11.2). Major curve improved from 60.3° to 35.3°, and was maintained at 40.6° at latest follow-up. Mean spring length increase during follow-up was 10.4mm/year. T1-S1 length increased 13.6mm/year and the instrumented segment length showed a mean increase of 0.8mm/segment/year. In total, 17 re-operations were performed. Ten re-operations were performed to treat 9 implant-related complications. In addition, 7 patients showed spinal growth that exceeded expected growth velocity; their springs were re-tensioned during a small re-operation. Spring distraction may be feasible as an alternative to current growing spine solutions. Curve correction and growth could be maintained satisfactory without the need for repetitive lengthening procedures. Complications and re-operations could not be prevented, which emphasizes the need for further improvement.

Abduction treatment in stable hip dysplasia does not alter the acetabular growth: results of a randomized clinical trial.

Background The effect of bracing over natural history of stable dysplastic hips is not well known. This multicenter randomized trial aimed at objectifying the effect of abduction treatment versus active surveillance in infants of 3 to 4 months of age. Methods Patients were randomized to either Pavlik harness or active surveillance group. Ultrasound was repeated at 6 and 12 weeks post randomization. The primary outcome was the degree of dysplasia using the Graf α-angle at 6 months of age. The measurement of the acetabular index (AI) on plain pelvis X-rays was used to identify persistent dysplasia after 9 months and walking age (after 18 months). Findings The Pavlik harness group (n = 55) and active surveillance group (n = 49) were comparable for predictors of outcome. At 12 weeks follow-up the mean α-angle was 60.5° ± 3.8° in the Pavlik harness group and 60.0° ± 5.6° in the active surveillance group. (p = 0.30). Analysis of secondary outcomes (standard of care) showed no treatment differences for acetabular index at age 10 months (p = 0.82) and walking age (p = 0.35). Interpretation Pavlik harness treatment of stable but sonographic dysplastic hips has no effect on acetabular development. Eighty percent of the patients will have a normal development of the hip after twelve weeks. Therefore, we recommend observation rather than treatment for stable dysplastic hips.

Correction of rotational deformity and restoration of thoracic kyphosis are inversely related in posterior surgery for adolescent idiopathic scoliosis.

Adolescent Idiopathic Scoliosis (AIS) is a complex three dimensional deformity the treatment of which remains to be surgical correction of the deformity as it had progressed over certain thresholds. The main focus in surgical treatment had, for decades, been the amount of correction in the coronal plane whereas corrections in sagittal and rotational (axial) planes have also been recognized as almost as important as the coronal over the recent decades. The hypotheses presented and discussed in this study is the virtual adversity between the rates of correction in these two (sagittal and axial) planes. Namely, we are suggesting that due to an elongated anterior spinal column as an intrinsic component of AIS, posterior surgery cannot correct both the axial plane deformity and the thoracic hypokyphosis in the sagittal plane at the same time, unless the posterior spinal column is substantially lengthened. This hypothesis is supported by 3D modeling of the AIS spine as well as the relative inability in changing the sagittal alignment of the thoracic spine demonstrated by a literature search by us. Understanding and internalization of this hypothesis by AIS surgeons is important as it suggests that by posterior instrumentation, unless a riskier approach of substantially lengthening the spinal column is taken, surgeons need to make the choice of correcting the hypokyphosis OR axial rotation.

Complex spine deformities in young patients with severe osteogenesis imperfecta: current concepts review.

The severity of osteogenesis imperfecta (OI), the associated reduced quality and quantity of collagen type I, the degree of bone fragility, ligamentous laxity, vertebral fractures and multilevel vertebral deformities all impair the mechanical integrity of the whole spinal architecture and relate to the high prevalence of progressive kyphoscoliotic deformities during growth. Bisphosphonate therapy may at best slow down curve progression but does not seem to lower the prevalence of deformities or the incidence of surgery. Brace treatment is problematic due to pre-existing chest wall deformities, stiffness of the curve and the brittleness of the ribs which limit transfer of corrective forces from the brace shell to the spine. Progressive curves entail loss of balance, chest deformities, pain and compromise of pulmonary function and eventually require surgical stabilization, usually around puberty. Severe vertebral deformities including deformed, small pedicles, highly brittle bones and chest deformities, short deformed trunks and associated issues like C-spine and cranial base abnormalities (basilar impressions, cervical kyphosis) as well as deformed lower and upper extremities are posing multiple peri- and intraoperative challenges. Hence, an early multidisciplinary approach (anaesthetist, pulmonologist, paediatric orthopaedic spine surgeon) is mandatory. This paper was written under the guidance of the Spine Study Group of the European Paediatric Orthopaedic Society. It highlights the most pertinent information given in the current literature and various practical aspects on surgical care of spine deformities in young OI patients based on the personal experience of the contributing authors.

Trigonometric Algorithm Defining the True Three-Dimensional Acetabular Cup Orientation: Correlation Between Measured and Calculated Cup Orientation Angles.

BACKGROUND: Acetabular cup orientation plays a key role in implant stability and the success of total hip arthroplasty. To date, the orientation has been measured with different imaging modalities and definitions, leading to lack of consensus on optimal cup placement. A 3-dimensional (3D) concept involving a trigonometric description enables unambiguous definitions. Our objective was to test the validity and reliability of a 3D trigonometric description of cup orientation. METHODS: Computed tomographic scans of the pelvis, performed for vascular assessment of 20 patients with 22 primary total hip replacements in situ, were systematically collected. On multiplanar reconstructions, 3 observers independently measured cup orientation retrospectively in terms of coronal inclination, sagittal tilt, and transverse version. The angles measured in 2 planes were used to calculate the angle in the third plane via a trigonometric algorithm. For correlation and reliability analyses, intraobserver and interobserver differences between measured and calculated angles were evaluated with use of the intraclass correlation coefficient (ICC). RESULTS: Measured and calculated angles had ICCs of 0.953 for coronal inclination, 0.985 for sagittal tilt, and 0.982 for transverse version. Intraobserver and interobserver reliability had ICCs of 0.987 and 0.987, respectively, for coronal inclination; 0.979 and 0.981, respectively, for sagittal tilt; and 0.992 and 0.978, respectively, for transverse version. CONCLUSIONS: The 3D concept with its trigonometric algorithm is a valid and reliable tool for the measurement of cup orientation. CLINICAL RELEVANCE: By calculating the transverse version of cups from coronal inclination and sagittal tilt measurements, the trigonometric algorithm enables a 3D definition of cup orientation, regardless of the imaging modality used. In addition, it introduces sagittal tilt that, like pelvic tilt, rotates around the transverse axis.

Long-term outcomes following the medial approach for open reduction of the hip in children with developmental dysplasia.

Aims Open reduction is required following failed conservative treatment of developmental dysplasia of the hip (DDH). The Ludloff medial approach is commonly used, but poor results have been reported, with rates of the development of avascular necrosis (AVN) varying between 8% and 54%. This retrospective cohort study evaluates the long-term radiographic and clinical outcome of dislocated hips treated using this approach. Patients and Methods Children with a dislocated hip, younger than one year of age at the time of surgery, who were treated using a medial approach were eligible for the study. Radiographs were evaluated for the degree of dislocation and the presence of an ossific nucleus preoperatively, and for the degree of AVN and residual dysplasia at one and five years and at a mean of 12.7 years (4.6 to 20.8) postoperatively. Radiographic outcome was assessed using the Severin classification, after five years of age. Further surgical procedures were recorded. Functional outcome was assessed using the Pediatric Outcomes Data Collection Instrument (PODCI) or the Hip Disability and Osteoarthritis Outcome Score (HOOS), depending on the patient's age. Results A total of 52 children (58 hips) were included. At the latest follow-up, 11 hips (19%) showed signs of AVN. Further surgery was undertaken in 13 hips (22%). A total of 13 hips had a poor radiological outcome with Severin type III or higher. Of these, the age at the time of surgery was significantly higher (p < 0.05) than in those with a good Severin type (I or II). The patient-reported outcomes were significantly worse (p < 0.05) in children with a poor Severin classification. Conclusion This retrospective long-term follow-up study shows that one in five children with DDH who undergo open reduction using a medial surgical approach has poor clinical and/or radiological outcome. The poor outcome is not related to the presence of AVN (19%), but due to residual dysplasia. Cite this article: Bone Joint J 2018;100-B:822-7.

A validated new histological classification for intervertebral disc degeneration.

UNLABELLED: Histology is an important outcome variable in basic science and pre-clinical studies regarding intervertebral disc degeneration (IVD). Nevertheless, an adequately validated histological classification for IVD degeneration is still lacking and the existing classifications are difficult to use for inexperienced observers. OBJECTIVE: Therefore the aim of this study was to develop and to validate a new histological classification for IVD degeneration. Moreover, the new classification was compared to the frequently used non-validated classification. METHODS: The new classification was applied to human IVD sections. The sections were scored twice by two independent inexperienced observers, twice by two experienced IVD researchers and once by a pathologist. For comparison, the sections were also scored according to the classification described by Boos et al. by two experienced IVD researchers. Macroscopic grading according Thompson et al., glycosaminoglycan (GAG) content and age were used for validation. RESULTS: The new classification had an excellent intra- and a good inter-observer reliability. Intraclass Correlation Coefficients (ICC) were 0.83 and 0.74, respectively. Intra- and inter-observer reliability were comparable for experienced and inexperienced observers. Statistically significant correlations were found between the new classification, macroscopic score, GAG content in the nucleus pulposus (NP) and age; Correlation coefficient (CC) 0.79, -0.62 and 0.68, respectively. The CCs of the Boos classification were all lower compared to the new classification. CONCLUSION: the new histological classification for IVD degeneration is a valid instrument for evaluating IVD degeneration in human IVD sections and is suitable for inexperienced and experienced researchers.

Reduction of blood loss with the use of a new combined intra-operative and post-operative autologous blood transfusion system compared with no drainage in primary total hip replacement.

Autologous retransfusion and no-drainage are both blood-saving measures in total hip replacement (THR). A new combined intra- and post-operative autotransfusion filter system has been developed especially for primary THR, and we conducted a randomised controlled blinded study comparing this with no-drainage. A total of 204 THR patients were randomised to autologous blood transfusion (ABT) (n = 102) or no-drainage (n = 102). In the ABT group, a mean of 488 ml (sd 252) of blood was retransfused. The mean lowest post-operative haemoglobin level during the hospital stay was higher in the autotransfusion group (10.6 g/dl (7.8 to 13.9) vs 10.2 g/dl (7.5 to 13.3); p = 0.01). The mean haemoglobin levels for the ABT and no-drainage groups were not significantly different on the first day (11.3 g/dl (7.8 to 13.9) vs 11.0 g/dl (8.1 to 13.4); p = 0.07), the second day (11.1 g/dl (8.2 to 13.8) vs 10.8 g/dl (7.5 to 13.3); p = 0.09) or the third day (10.8 g/dl (8.0 to 13.0) vs 10.6 g/dl (7.5 to 14.1); p = 0.15). The mean total peri-operative net blood loss was 1464 ml (sd 505) in the ABT group and 1654 ml (sd 553) in the no-drainage group (p = 0.01). Homologous blood transfusions were needed in four patients (3.9%) in the ABT group and nine (8.8%) in the no-drainage group (p = 0.15). No statistically significant difference in adverse events was found between the groups. The use of a new intra- and post-operative autologous blood transfusion filter system results in less total blood loss and a smaller maximum decrease in haemoglobin levels than no-drainage following primary THR.

Prevalence and development of orthopaedic symptoms in the dutch hurler patient population after haematopoietic stem cell transplantation.

Hurler syndrome (MPS-IH) is a rare autosomal recessive lysosomal storage disease. Besides a variety of other features, Hurler syndrome is characterized by a range of skeletal abnormalities known as dysostosis multiplex. Despite the successful effect of haematopoietic stem cell transplantation on the other features, dysostosis remains a disabling symptom of the disease. This study analyzed the status and development of the orthopaedic manifestations of 14 Dutch Hurler patients after stem cell transplantation.Data were obtained retrospectively by reviewing patients' charts, radiographs and MRIs. Existing methods to measure the deficiencies were modified to optimally address the dysostosis. These measurements were done by two of the authors independently. The odontoïd/body ratio, kyphotic angle, scoliotic angle and parameters for hip dysplasia and genu valgum were measured and plotted against age. The degree of progression was determined. The intraclass correlation coefficient (ICC) was calculated to determine the reliability of the measurements.All patients showed hypoplasia of the odontoïd, which significantly improved during growth. Kyphosis in the thoracolumbar area was present in 13 patients and proved to be progressive. Scoliosis was observed in eight patients. Hip dysplasia was present in all patients and showed no tendency of improvement. In all but one patient, knee valgus remained more than two standard deviations above normal.Dysostosis remains a major problem after haematopoietic stem cell transplantation in Hurler patients. Moreover, except for dens hypoplasia, it appears to be progressive and therefore surgical interventions may be necessary in the majority of these patients.

The safety and feasibility of a less invasive distal femur closing wedge osteotomy technique: a cadaveric dissection study of the medial aspect of the distal femur.

PURPOSE: To investigate the feasibility and safety of a less invasive surgical approach to the distal medial aspect of the femur in supracondylar medial closing wedge osteotomy for the treatment of lateral compartment osteoarthritis of the knee. The aim of a less invasive approach is to minimize soft tissue disruption, reduce damage to neurovascular structures and thereby prevent muscle atrophy and optimize bone healing potential. METHODS: A human cadaver dissection study on the vascular and neural structures of the medial side of the distal femur was conducted. Surgical dissection (n = 4), cryomicrotomy and subsequent 3D reconstruction of the anatomy (n = 1), and surgical dissection after performance of a supracondylar osteotomy through a less invasive approach (n = 1) were performed in 6 legs in total. RESULTS: The surgical dissection and 3D reconstruction showed that a branch of the femoral artery, the distal genicular artery, supplies the distal area of the vastus medialis (VM) muscle. This artery has several branching patterns; crucial in the presented less invasive approach is its musculo-articular branch, which has an oblique course through the VM to the superomedial pole of the patella. The femoral nerve and saphenous nerve innervate the VM. These structures are at risk in the traditional subvastus approach, whereas no major damage was observed in the leg in which a less invasive approach was performed. CONCLUSIONS: In this cadaveric dissection study, a less invasive approach to the medial side of the distal femur proved to be feasible and safe. Damage to the VM and its neurovascular structures is minimized as compared to the traditional subvastus approach.

dGEMRIC as a tool for measuring changes in cartilage quality following high tibial osteotomy: a feasibility study.

OBJECTIVE: The high tibial osteotomy (HTO) is an effective strategy for treatment of painful medial compartment knee osteoarthritis. Effects on cartilage quality are largely unknown. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) enables non-invasive assessment of cartilage glycosaminoglycan content. This study aimed to evaluate if dGEMRIC could detect relevant changes in cartilage glycosaminoglycan content following HTO. DESIGN: Ten patients with medial compartment osteoarthritis underwent a dGEMRIC scan prior to HTO, and after bone healing and subsequent hardware removal. A dGEMRIC index (T1Gd) was used for changes in cartilage glycosaminoglycan content, a high T1Gd indicating a high glycosaminoglycan content and vice versa. Radiographic analysis included mechanical axis and tibial slope measurement. clinical scores [knee osteoarthritis outcome scale (KOOS), visual analogue score (VAS) for pain, Knee Society clinical rating system (KSCRS)] before, 3 and 6 months after HTO and after hardware removal were correlated to T1Gd changes. RESULTS: Overall a trend towards a decreased T1Gd, despite HTO, was observed. Before and after HTO, lateral femoral condyle T1Gd was higher than medial femoral condyle (MFC) T1Gd and tibial cartilage T1Gd was higher than that of femoral cartilage (P < 0.001). The MFC had the lowest T1Gd before and after HTO. Clinical scores all improved significantly (P < 0.01), KOOS Symptoms and QOL were moderately related to changes in MFC T1Gd. CONCLUSIONS: dGEMRIC effectively detected differences in cartilage quality within knee compartments before and after HTO, but no changes due to HTO were detected. Hardware removal post-HTO seems essential for adequate T(1)Gd interpretation. T(1)Gd was correlated to improved clinical scores on a subscore level only. Longer follow-up after HTO may reveal lasting changes. ClinicalTrials.gov registration ID: NCT01269944.

Micro-CT quantification of subchondral endplate changes in intervertebral disc degeneration.

BACKGROUND: The intervertebral disc (IVD) is dependent on nutrient provision through a cartilage layer with underlying subchondral bone, analogous to joint cartilage. In the joint, subchondral bone remodeling has been associated with osteoarthritis (OA) progression due to compromised nutrient and gas diffusion and reduced structural support of the overlaying cartilage. However, subchondral bone changes in IVD degeneration have never been quantified before. OBJECTIVE: The aim of this study is to determine the subchondral bone changes at different stages of IVD degeneration by micro-CT. METHODS: Twenty-seven IVDs including the adjacent vertebral endplates were obtained at autopsy. Midsagittal slices, graded according the Thompson score, were scanned. Per scan 12 standardized cylindrical volumes of interest (VOI) were selected. Six VOIs contained the bony endplate and trabeculae (endplate VOIs) and six accompanying VOIs only contained trabecular bone (vertebral VOIs). Bone volume as percentage of the total volume (BV/TV) of the VOI, trabecular thickness (TrTh) and connectivity density (CD) were determined. RESULTS: An increase in BV/TV and TrTh was found in endplate VOIs of IVDs with higher Thompson score whereas these values remained stable or decreased in the vertebral VOIs. CONCLUSION: The increase in bone volume combined with the increase in TrTh in endplate VOIs strongly suggest that the subchondral endplate condenses to a more dense structure in degenerated IVDs. This may negatively influence the diffusion and nutrition of the IVD. The endplate differences between intact and mild degenerative IVDs (grade II) indicate an early association of subchondral endplate changes with IVD degeneration.