The incidence of Achilles tendon rupture is increasing as more people participate in sports and physical activities.However, whether to treat a complete rupture of the Achilles tendon, conservatively or operatively, is still controversial.Current studies show that the nonoperative treatment of acute Achilles tendon rupture with short-term immobilization for up to two weeks and subsequent accelerated functional rehabilitation with protected weight-bearing results in similar functional outcomes and re-rupture rates compared to those treated surgically.Also, nonoperative treatment does not risk any surgical morbidity such as wound problems, infection, and nerve injury.Therefore, the treatment options for acute Achilles tendon rupture should be carefully chosen in consultation with patients regarding possible clinical outcomes and complications of both treatment options.

Category: Sports Introduction/Purpose: There is a controversy if non-operative or operative treatment for acute Achilles tendon rupture is superior. It is unknown, if young and active patients with acute Achilles tendon rupture, return to previous sports activity level after treatment with standardized non-operative immediate full weight-bearing protocol. The purpose of this was to assess (1) the return-to-sport rate and subjective satisfaction in patients with different activity levels before the rupture, at 1-year, and at 5-year follow-up, (2) the clinical outcome at 1-year follow-up, and (3) re-ruptures and complications. Methods: Out of 171 consecutive patients that were treated nonoperatively, 114 patients were available for 1-year follow-up. Eighty-nine patients responded to questionnaires for sports activity. Non-operative treatment consisted of a combination of an equinus cast and rehabilitation boot, that enables immediate full weight-bearing and early functional rehabilitation. Clinical 1-year follow-up and follow-up with questionnaires at 1-year and 5-year follow-up were evaluated to calculate Tegner Activity Scale (TAS), and Activity Rating Scale (ARS) and were compared to the status before the rupture. Based on the TAS before the rupture, patients were divided into a low-level activity (<5) and high-level activity (>5) group and the return-to-sport rate was compared between those two groups.Clinical assessment at minimum 1-year follow-up included testing of plantarflexion strength and endurance, calf circumference, and subjective parameters to calculate a modified Thermann score. Mean clinical follow-up was 34 ± 23 months (range 12-88 months). Results: (1) A significantly higher proportion (91%) of the patients in the low-level activity group returned to their previous TA at 5-year follow-up compared to patients (67%) in the high-level activity group (p=0.029). A higher proportion (91%) of the patients in the low-level activity group returned to their previous ARS Score at 5-year follow-up compared to patients (82%) in the high- level activity group (p=0,115). (2) The mean Thermann score was not significantly different between the two activity groups at minimum 1-year follow-up: 84 ±12 (range, 41-100) and 82 ±12 (range, 44 -100). (3) There were a total of 17 complications. There were 9,6% reruptures (8 with and 3 without an adequate trauma), 5 deep venous thromboses, 1 complex regional pain syndrome at 1 year follow-up. Conclusion: After 17 years of prospective evaluation, our non-operative treatment protocol for acute rupture of the Achilles tendon leads to good functional outcome, high patient satisfaction and high return-to-sport rate. Most patients return to their previous sports activity level after a standardized nonoperative early full-weightbearing treatment protocol for acute Achilles tendon rupture. Even for patients with a high activity level return to pre-rupture sports level activity was possible in two third of the patients. The re-rupture rate with immediate weight bearing is low and comparable to other non-operative treatment methods.

We developed and validated a small, easy to use and cost-effective augmented marker-based hybrid navigation system for peri-acetabular osteotomy (PAO) surgery. The hybrid system consists of a tracking unit directly placed on the patient's pelvis, an augmented marker with an integrated inertial measurement unit ('MU) attached to the patient's acetabular fragment and the host computer. The tracking unit sends a live video stream of the marker to the host computer where the marker's pose is estimated. The augmented marker with the 'MU sends its pose estimate to the host computer where we apply sensor fusion to compute the final marker pose estimate. The host computer then tracks the orientation of the acetabular fragment during peri-acetabular osteotomy surgery. Anatomy registration is done using a previously developed registration device. A Kalman filter-based sensor fusion was added to complete the system. A plastic bone study was performed for validation between an optical tracking-based navigation system and our proposed system. Mean absolute difference for inclination and anteversion was 1.63 degrees and 1.55 degrees, respectively. The results show that our system is able to accurately measure the orientation of the acetabular fragment.

IntroductionCorrect postoperative leg length restoration is among the most important goals of hip arthroplasty. Therefore, we developed, validated and clinically applied a novel software algorithm based on surgical navigation, which allows the surgeon to restore a defined femur position without establishing a femoral coordinate system or the hip joint center and measure the leg length accurately and simply.Material and MethodsThis new leg length algorithm was used in 154 hips (145 patients) that underwent CT-based computer-assisted THA (VectorVision Build 274 prototype; BrainLAB AG, Helmstetten, Germany) with a tissue preserving superior capsulotomy. Intraoperatively, a pelvic and a femoral dynamic reference bases (DRB) were applied and the anterior pelvic plane (APP) was set as the pelvic coordinate system. Then, the hip joint was put in a neutral position and this position, and the relative position of the femoral DRB relative to the pelvic DRB, was captured and stored by the navigation system. After im...

INTRODUCTION:A preoperative planning approach for percutaneous screw fixation of the iliosacral joint provides specific entry points (EPs) and aiming points (APs) of intraosseous screw pathways (as defined by CT scans) for lateral fluoroscopic projections used intraoperatively. The potential to achieve the recommended EPs and APs, to obtain an ideal screw position (perpendicular to the iliosacral joint), to avoid occurrence of extraosseous screw misplacement, to reduce the operating time and the radiation exposure by utilizing this planning approach have not been described yet.METHODS:On preoperative CT scans of eight human cadaveric specimen individual EPs and APs were identified and transferred to the lateral fluoroscopic projection using a coordinate system with the zero-point in the center of the posterior cortex of the S1 vertebral body (x-axis parallel to upper S1 endplate). Distances were expressed in relation to the anteroposterior distance of the S1 upper endplate (in%). In each specimen on one side a screw was placed with provided EP and AP (New Technique) whereas at the contralateral side a screw was placed without given EP and AP (Conventional Technique). Both techniques were compared using postoperative CT scans to assess distances between predefined EPs and APs and the actually obtained EPs and APs, screw angulations in relation to the iliosacral joint in coronal and axial planes and the occurrence of any extraosseous screw misplacement. The "operating time (OT)" and the "time under fluoroscopy (TUF)" were recorded. Statistical analysis was performed by the Wilcoxon signed-rank test.RESULTS:EPs were realized significantly more accurate using the new technique in vertical direction. The screw positions in relation to the iliosacral joint showed no significant difference between both techniques. Both techniques had one aberrantly placed screw outside the safe corridor. The (mean±SD) "OT" and the (mean±SD) "TUF" were significantly decreased using the new technique compared to the conventional technique (OT: 7.6±2min versus 13.1±5.8min, p=0.012; TUF: 1.5±0.8min versus 2.2±1.1min).CONCLUSION:The presented preoperative planning approach increases the accuracy in percutaneous screw fixation of the iliosacral joint, reduces operating time and minimizes radiation exposure to patient and staff.

Study Design: Retrospective case series. Objective: Short posterior stabilization with vertebroplasty is one treatment option for thoracolumbar burst fractures (AO A3). Whether it avoids progression in segmental kyphosis, especially after implant removal, is unclear. In a retrospective case-control study, its stability and the effect on intervertebral discs with and without implant removal was studied. Methods: Fifty-nine consecutive patients were treated with bisegmental short posterior instrumentation and additional vertebroplasty of the fractured vertebra. Twenty-nine patients (male/female 17/12; age: 41.7 ± 15.4 years) underwent implant removal. Changes of segmental kyphosis and disc heights between both groups (with and without implant removal) were compared on lateral X-rays preoperative, postoperative, after 1 year and after implant removal. Risk factors for loss of reduction were analyzed. Results: Kyphosis increased up to 12 months after implant removal. The loss of bisegmental correction was 6.0 ± 4.2 (range 0° to 16°) 12 months after implant removal. Risk factors for loss of reduction are younger patient age, fractures of the thoracolumbar junction (Th12), and degree of traumatic kyphosis. Intervertebral discs traversed by the stabilization lose height and don’t recover within 1 year after implant removal. Without implant removal, disc height of the lower adjacent level is reduced after 24 months. Conclusions: Short posterior stabilization in combination with vertebroplasty is a treatment alternative for thoracic and lumbar AO A3 fractures. After implant removal kyphosis increases, predominantly in the segment above the augmented vertebra. Risk factors for loss of reduction include younger age, fractures of the thoracolumbar junction (T12), and higher fracture kyphosis.

Purpose The pararectus approach has been validated for managing acetabular fractures. We hypothesised it might be an alternative approach for performing periacetabular osteotomy (PAO).Methods Using four cadaver specimens, we randomly performed PAO through either the pararectus or a modified Smith-Petersen (SP) approach. We assessed technical feasibility and safety. Furthermore, we controlled fragment mobility using a surgical navigation system and compared mobility between approaches. The navigation system's accuracy was tested by cross-examination with validated preoperative planning software.Results The pararectus approach is technically feasible, allowing for adequate exposure, safe osteotomies and excellent control of structures at risk. Fragment mobility is equal to that achieved through the SP approach. Validation of these measurements yielded a mean difference of less < 1 mm without statistical significance.Conclusion Experimental data suggests the pararectus approach might be an alternative approach for performing PAO. Clinical validation is necessary to confirm these promising preliminary results.

Purpose To evaluate a low-cost, inertial sensor-based surgical navigation solution for periacetabular osteotomy (PAO) surgery without the line-of-sight impediment. Methods Two commercial inertial measurement units (IMU, Xsens Technologies, The Netherlands), are attached to a patient’s pelvis and to the acetabular fragment, respectively. Registration of the patient with a pre-operatively acquired computer model is done by recording the orientation of the patient’s anterior pelvic plane (APP) using one IMU. A custom-designed device is used to record the orientation of the APP in the reference coordinate system of the IMU. After registration, the two sensors are mounted to the patient’s pelvis and acetabular fragment, respectively. Once the initial position is recorded, the orientation is measured and displayed on a computer screen. A patient-specific computer model generated from a pre-operatively acquired computed tomography scan is used to visualize the updated orientation of the acetabular fragment. Results Experiments with plastic bones (eight hip joints) performed in an operating room comparing a previously developed optical navigation system with our inertial-based navigation system showed no statistically significant difference on the measurement of acetabular component reorientation. In all eight hip joints the mean absolute difference was below four degrees. Conclusion Using two commercially available inertial measurement units we show that it is possible to accurately measure the orientation (inclination and anteversion) of the acetabular fragment during PAO surgery and therefore to successfully eliminate the line-of-sight impediment that optical navigation systems have.

Femoroacetabular impingement (FAI) is a dynamic conflict of the hip defined by a pathological, early abutment of the proximal femur onto the acetabulum or pelvis. In the past two decades, FAI has received increasing focus in both research and clinical practice as a cause of hip pain and prearthrotic deformity. Anatomical abnormalities such as an aspherical femoral head (cam-type FAI), a focal or general overgrowth of the acetabulum (pincer-type FAI), a high riding greater or lesser trochanter (extra-articular FAI), or abnormal torsion of the femur have been identified as underlying pathomorphologies. Open and arthroscopic treatment options are available to correct the deformity and to allow impingement-free range of motion. In routine practice, diagnosis and treatment planning of FAI is based on clinical examination and conventional imaging modalities such as standard radiography, magnetic resonance arthrography (MRA), and computed tomography (CT). Modern software tools allow three-dimensional analysis of the hip joint by extracting pelvic landmarks from two-dimensional antero-posterior pelvic radiographs. An object-oriented cross-platform program (Hip(2)Norm) has been developed and validated to standardize pelvic rotation and tilt on conventional AP pelvis radiographs. It has been shown that Hip2Norm is an accurate, consistent, reliable and reproducible tool for the correction of selected hip parameters on conventional radiographs. In contrast to conventional imaging modalities, which provide only static visualization, novel computer assisted tools have been developed to allow the dynamic analysis of FAI pathomechanics. In this context, a validated, CT-based software package (HipMotion) has been introduced. HipMotion is based on polygonal three-dimensional models of the patient's pelvis and femur. The software includes simulation methods for range of motion, collision detection and accurate mapping of impingement areas.A preoperative treatment plan can be created by performing a virtual resection of any mapped impingement zones both on the femoral head-neck junction, as well as the acetabular rim using the same three-dimensional models. The following book chapter provides a summarized description of current computer-assisted tools for the diagnosis and treatment planning of FAI highlighting the possibility for both static and dynamic evaluation, reliability and reproducibility, and its applicability to routine clinical use.

Periacetabular osteotomy (PAO) is an effective approach for surgical treatment of hip dysplasia in young adults. However, achieving an optimal acetabular reorientation during PAO is the most critical and challenging step. Routinely, the correct positioning of the acetabular fragment largely depends on the surgeons experience and is done under fluoroscopy to provide the surgeon with continuous live x-ray guidance. To address these challenges, we developed a computer assisted system. Our system starts with a fully automatic detection of the acetabular rim, which allows for quantifying the acetabular 3D morphology with parameters such as acetabular orientation, femoral head Extrusion Index (EI), Lateral Center Edge (LCE) angle, total and regional femoral head coverage (FHC) ratio for computer assisted diagnosis, planning and simulation of PAO. Intra-operative navigation is used to implement the pre-operative plan. Two validation studies were conducted on four sawbone models to evaluate the efficacy of the system intra-operatively and post-operatively. By comparing the pre-operatively planned situation with the intra-operatively achieved situation, average errors of \(0.6^\circ \pm 0.3^\circ \), \(0.3^\circ \pm 0.2^\circ \) and \(1.1^\circ \pm 1.1^\circ \) were found respectively along three motion directions (Flexion/Extension, Abduction/Adduction and External Rotation/Internal Rotation). In addition, by comparing the pre-operatively planned situation with the post-operative results, average errors of \(0.9^\circ \pm 0.3^\circ \) and \(0.9^\circ \pm 0.7^\circ \) were found for inclination and anteversion, respectively.

Background: Acute traumatic rupture of the Achilles tendon can be treated operatively or nonoperatively. Throughout the literature, there is no consensus regarding the optimal treatment protocol. Purpose: To report on 17 years of experience with treating this injury with a standardized nonoperative treatment protocol. Study Design: Case Series; Level of evidence, 4. Methods: The treatment protocol was based on a combination of an equinus cast and rehabilitation boot, which promoted immediate full weightbearing and early functional rehabilitation. A total of 171 patients were consecutively treated and prospectively followed from 1996 to 2013. Assessed were subjective parameters such as pain, loss of strength, return to previous activity level, meteosensitivity, and general satisfaction with the treatment outcome. Clinical assessment included testing of plantar flexion strength and endurance, calf circumference, and tendon length. Subjective and clinical parameters were then used to calculate a modified Thermann score. The correlation between tendon lengthening and function was calculated using the Pearson correlation coefficient. Results: A total of 114 patients were followed for a minimum of 12 months (mean, 27 ± 20 months; range, 12-88 months). The mean Thermann score was 82 ± 13 (range, 41-100), and subjective satisfaction was rated “very good” and “good” in 90%. An inverse correlation was found between tendon length and muscle strength ( R = −0.3). There were 11 reruptures (8 with and 3 without an adequate trauma). General complications were 5 deep venous thromboses, 1 complex regional pain syndrome, and minor problems such as transient heel pain (n = 3), heel numbness (n = 1), and cast-associated skin abrasions (n = 4). Conclusion: Seventeen years of experience with a nonoperative treatment protocol for acute rupture of the Achilles tendon confirmed good functional outcome and patient satisfaction. Reruptures mostly occurred with new traumatic events in the vulnerable phase from 6 to 12 weeks after the initial injury. Muscle strength correlated to tendon length, making its assessment a crucial follow-up parameter. The protective equinus cast and boot can protect against excessive tendon lengthening during the healing process.

Modern computerized planning tools for periacetabular osteotomy (PAO) use either morphology-based or biomechanics-based methods. The latter relies on estimation of peak contact pressures and contact areas using either patient specific or constant thickness cartilage models. We performed a finite element analysis investigating the optimal reorientation of the acetabulum in PAO surgery based on simulated joint contact pressures and contact areas using patient specific cartilage model. Furthermore we investigated the influences of using patient specific cartilage model or constant thickness cartilage model on the biomechanical simulation results. Ten specimens with hip dysplasia were used in this study. Image data were available from CT arthrography studies. Bone models were reconstructed. Mesh models for the patient specific cartilage were defined and subsequently loaded under previously reported boundary and loading conditions. Peak contact pressures and contact areas were estimated in the original position. Afterwards we used a validated preoperative planning software to change the acetabular inclination by an increment of 5° and measured the lateral center edge angle (LCE) at each reorientation position. The position with the largest contact area and the lowest peak contact pressure was defined as the optimal position. In order to investigate the influence of using patient specific cartilage model or constant thickness cartilage model on the biomechanical simulation results, the same procedure was repeated with the same bone models but with a cartilage mesh of constant thickness. Comparison of the peak contact pressures and the contact areas between these two different cartilage models showed that good correlation between these two cartilage models for peak contact pressures (r = 0.634 ∈ [0.6, 0.8], p < 0.001) and contact areas (r = 0.872 > 0.8, p < 0.001). For both cartilage models, the largest contact areas and the lowest peak pressures were found at the same position. Our study is the first study comparing peak contact pressures and contact areas between patient specific and constant thickness cartilage models during PAO planning. Good correlation for these two models was detected. Computer assisted planning with FE modeling using constant thickness cartilage models might be a promising PAO planning tool when a conventional CT is available.

Pelvic osteotomies improve containment of the femoral head in cases of developmental dysplasia of the hip or in femoroacetabular impingement due to acetabular retroversion. In the evolution of osteotomies, the Ganz Periacetabular Osteotomy (PAO) is among the complex reorientation osteotomies and allows for complete mobilization of the acetabulum without compromising the integrity of the pelvic ring. For the complex reorientation osteotomies, preoperative planning of the required acetabular correction is an important step, due to the need to comprehend the three-dimensional (3D) relationship between acetabulum and femur. Traditionally, planning was performed using conventional radiographs in different projections, reducing the 3D problem to a two-dimensional one. Known disturbance variables, mainly tilt and rotation of the pelvis make assessment by these means approximate at the most. The advent of modern enhanced computation skills and new imaging techniques gave room for more sophisticated means of preoperative planning. Apart from analysis of acetabular geometry on conventional x-rays by sophisticated software applications, more accurate assessment of coverage and congruency and thus amount of correction necessary can be performed on multiplanar CT images. With further evolution of computer-assisted orthopaedic surgery, especially the ability to generate 3D models from the CT data, examiners were enabled to simulate the in vivo situation in a virtual in vitro setting. Based on this ability, different techniques have been described. They basically all employ virtual definition of an acetabular fragment. Subsequently reorientation can be simulated using either 3D calculation of standard parameters of femoroacetabular morphology, or joint contact pressures, or a combination of both. Other techniques employ patient specific implants, templates or cutting guides to achieve the goal of safe periacetabular osteotomies. This chapter will give an overview of the available techniques for planning of periacetabular osteotomy.

Purpose. To develop and evaluate a low-cost, surgical navigation solution for periacetabular osteotomy (PAO) surgery. Methods. A commercially available low-cost miniature computer is used together with a camera board (Raspberry Pi 2 Model B, Camera Module PiNoir) to track planar markers (Aruco markers). The overall setup of the tracking unit is small enough to be attached directly to the patient’s pelvis. The patient’s pelvis is registered by estimating the pose of a planar marker which is attached to an anterior pelvic plane (APP) digitization device. Next, one marker is attached to the acetabular fragment and the initial orientation of the fragment is recorded. The estimated orientation of the fragment is transmitted to the host computer for visualization. Results. A plastic bone study (eight hip joints) was performed to validate the proposed system. The comparison with a previously developed optical tracking-based system showed no statistical significant difference between measurements obtained from the two systems. In all eight hip joints the mean absolute difference was below 2 ^∘ for both anteversion and inclination and a very strong correlation was observed. Conclusions. We show that with our proof-of-principle system, we are able to compute the acetabular orientation accurately.

Periacetabular Osteotomy (PAO) is a joint preserving surgical intervention intended to increase femoral head coverage and thereby to improve stability in young patients with hip dysplasia. Previously, we developed a CT-based, computer-assisted program for PAO diagnosis and planning, which allows for quantifying the 3D acetabular morphology with parameters such as acetabular version, inclination, lateral center edge (LCE) angle and femoral head coverage ratio (CO). In order to verify the hypothesis that our morphology-based planning strategy can improve biomechanical characteristics of dysplastic hips, we developed a 3D finite element model based on patient-specific geometry to predict cartilage contact stress change before and after morphology-based planning. Our experimental results demonstrated that the morphology-based planning strategy could reduce cartilage contact pressures and at the same time increase contact areas. In conclusion, our computer-assisted system is an efficient tool for PAO planning.

This study aimed at assessing the cement leakage rate and the filling pattern in patients treated with vertebroplasty, kyphoplasty and stentoplasty with and without a newly developed lavage technique.Retrospective clinical case-control study.A newly developed bipedicular lavage technique prior to cement application was applied in 64 patients (45.1 %) with 116 vertebrae, ("lavage" group). A conventional bipedicular cement injection technique was used in 78 patients (54.9 %) with 99 levels ("controls"). The outcome measures were filling patterns and leakage rates.The overall leakage rate (venous, cortical defect, intradiscal) was 37.9 % in the lavage and 83.8 % in the control group (p < 0.001). Venous leakage (lavage 12.9 % vs. controls 31.3 %; p = 0.001) and cortical defect leakage (lavage 17.2 % vs. controls 63.3 %; p < 0.001) were significantly lower in the lavage group compared to "controls," whereas intradiscal leakages were similar in both groups (lavage 12.1 % vs. controls 15.2 %; p = 0.51). For venous leakage multivariate logistic regression analysis showed lavage to be the only independent predictor. Lavage was associated with 0.33-times (95 % CI 0.16-0.65; p = 0.001) lower likelihood for leakage in compared to controls.Vertebral body lavage prior to cement augmentation is a safe technique to reduce cement leakage in a clinical setting and has the potential to prevent pulmonary fat embolism. Moreover, a better filling pattern can be achieved.