Extensor tendon rupture and preoperative mri confirmations of suture anchor prolapse: a case report and literature review.

BACKGROUND: While suture anchors are widely used in medical procedures for their advantages, they can sometimes lead to complications, including anchor prolapse. This article presents a unique case of suture anchor prolapse at the base of the distal phalanx of the little finger after extensor tendon rupture reconstruction surgery. CASE PRESENTATION: A 35-year-old male, underwent extensor tendon rupture reconstruction using a non-absorbable suture anchor. After seven years the patient visited our outpatients complaining of stiffness, pain, and protrusion at the surgical site. Initial X-ray imaging suggested suggesting either a fracture of the distal phalanx or tendon adhesion but lacked a definitive diagnosis. Subsequent magnetic resonance imaging (MRI) revealed bone connectivity between the middle and distal phalanges with irregular signal shadow and unclear boundaries while maintaining a regular finger shape. MRI proved superior in diagnosing prolapsed suture anchors, marking the first reported case of its kind. Surgical intervention confirmed MRI findings. CONCLUSIONS: Suture anchor complications, such as prolapse, are a concern in medical practice. This case underscores the significance of MRI for accurate diagnosis and the importance of tailored surgical management in addressing this uncommon complication.

Radiological evaluation before and after treatment with an osseointegrated bone-anchor following major limb amputation-a guide for radiologists.

Osseointegrated implants have been developed to allow direct skeletal fixation of a prosthesis as an alternative to traditional socket-fitted prostheses for patients who have suffered from a major limb amputation. The implants contribute to improvements in functional outcome and quality of life and radiological evaluation plays a crucial role in pre- and post-operative assessment. This article acts as a guide for radiologists who may be tasked with providing the radiological information required by surgeons and prosthetists. We also look at the radiological appearances of complications that may arise in patients treated with an osseointegrated implant. Plain X-rays are used to screen patients who wish to undergo treatment. Limb-length X-rays are then used to measure the length of any residual bone, and comparisons can be made with the normal side (if present). From this, decisions about the likely size of the implant and the need for further amputation can be made. CT scans enable accurate assessment of the medullary cavity and cortical thickness. Post-operatively, plain X-rays form the mainstay of the routine monitoring of the bone-implant interface. Potential complications include infection, aseptic loosening, mechanical fracture of the implant and periprosthetic fracture. Infection and aseptic loosening can be seen as a lucency at the bone-implant interface which (if left untreated) can lead to loss of the implant. Implant and periprosthetic fractures are radiographically obvious. Radiologists involved in the care of patients undergoing treatment with an osseointegrated implant should become familiar with the imaging requirements so they can contribute to optimal patient outcomes.

Beyond the pedicle screw-a patent review.

PURPOSE: This review provides an overview of the patent literature on posteriorly placed intrapedicular bone anchors. Conventional pedicle screws are the gold standard to create a fixation in the vertebra for spinal fusion surgery but may lack fixation strength, especially in osteoporotic bone. The ageing population demands new bone anchors that have an increased fixation strength, that can be placed safely, and, if necessary, can be removed without damaging the surrounding tissue. METHODS: The patent search was conducted using a classification search in the Espacenet patent database. Only patents with a Cooperative Patent Classification of A61B17/70 or A61B17/7001 concerning spinal positioners and stabilizers were eligible for inclusion. The search query resulted in the identification of 731 patents. Based on preset inclusion criteria, a total of 56 unique patents on different anchoring methods were included, reviewed and categorized in this study. RESULTS: Five unique fixation methods were identified; (1) anchors that use threading, (2) anchors that utilize a curved path through the vertebra, (3) anchors that (partly) expand, (4) anchors that use cement and (5) anchors that are designed to initiate bone ingrowth. Of the anchor designs included in this study, eight had a corresponding commercial product, six of which were evaluated in clinical trials. CONCLUSION: This review provides insights into worldwide patented intrapedicular bone anchors that aim to increase the fixation strength compared to the conventional pedicle screw. The identified anchoring methods and their working principles can be used for clinical decision-making and as a source of inspiration when designing novel bone anchors.

[Avulsion injuries of the adductors and iliopsoas]. / Avulsionsverletzungen der Adduktoren und des Iliopsoas.

Avulsion injuries of the tendon-bone junction of the adductor longus are rare. Avulsions of the iliopsoas tendon insertion on the lesser trochanter are even rarer. Avulsion injuries of the adductor insertion occur predominantly in active athletes. Iliopsoas tendon avulsions are described mainly in nonathletes, in old age and frequently with no triggering event. In these cases possible underlying pathologies (e.g. tumor or metastases in the lesser trochanter) must be ruled out. In the literature no generally accepted recommendations for treatment of these injuries can be found because only a few retrospective anecdotal case reports and case studies have been published. For this reason, it is mostly unclear if and when a conservative or operative approach is indicated.A PubMed/Medline literature search resulted in 86 articles for iliopsoas avulsions and 155 hits for adductor tendon avulsions. Accordingly, both injuries can basically be treated conservatively. A surgical treatment is recommended only occasionally when conservative treatment fails and when the adductor insertion or the apophysis of the lesser trochanter is dislocated more than 2 cm after avulsion. Reinsertion for adductor longus tendon avulsion injuries is usually performed by open repair using various anchor systems, while extensive avulsion injuries or non-unions of the apophysis of the lesser trochanter are treated by refixation by cannulated screw systems or resection and anchor refixation of the tendon. The postoperative outcome in most cases is described as good or very good (excellent). No major complications were reported in both groups.

Postoperative results of distal tibialis anterior tendinosis.

INTRODUCTION: Although distal tibialis anterior tendinopathy is a common condition, it has rarely been described in literature. It is often a condition in overweight women around 50-70 years old with pain that worsens at night. The purpose of this retrospective study is to describe the specific clinical signs and postoperative results of distal tibialis anterior tendinopathy. MATERIAL AND METHODS: Between 2013 and 2017 we operated 9 patients (10ft) who failed a conservative treatment of distal tibialis anterior tendinopathy. Surgery consisted of debridement of the diseased tendon and reinsertion with a bone anchor. There was a minimum follow-up of 12 months. All patients were clinically evaluated postoperative (range 14-57 months after surgery) with the use of the American Orthopaedic Foot and Ankle Society (AOFAS) score and Visual Analog Scale (VAS) RESULTS: The mean AOFAS score postoperative was 99 (range 94-100). The mean VAS score postoperative was 1 (range 0-3). In all 10 cases the patient was completely satisfied with the result following surgery. There was no recurrence or rupture of tendon after debridement. CONCLUSION: Distal tibialis anterior tendinopathy is mainly a clinical diagnosis where conservative treatment should always be the first choice. However, our results show that when conservative treatment fails, surgical treatment can lead to very good long term results with a high level of patient satisfaction.

The Accommodation of Bone Anchors Within the Distal Phalanx for Repair of Flexor Digitorum Profundus Avulsions.

PURPOSE: Avulsion injury of the flexor digitorum profundus (FDP) tendon has been traditionally repaired with a pull-out suture over the nail plate. Complication rates with this method and improvements in anchor design have led to the increased use of bone anchors to give a rigid all-inside repair. However, the dimensions of the distal phalanx may limit their use. The primary hypothesis was that 2 micro bone anchors could fit in either perpendicular or 45° proximally angled positions within each distal phalanx. A further hypothesis was that 1 mini bone anchor could fit in similar positions in the distal phalanx. METHODS: Thirty-two fresh frozen fingers were dissected, and the FDP tendon was removed from the distal phalanx footprint. Two bone anchor types were used, mini and micro sizes, and inserted at 2 angles, perpendicular and 45° proximally angled. Observations of dorsal cortex and joint space penetration were recorded. Distal phalanx dimensions were measured for each finger. RESULTS: The micro anchors penetrated the dorsal cortex in perpendicular tests in little fingers only. The micro anchor did not penetrate the joint in any angled tests. The mini bone anchor penetrated the dorsal cortex in 100% of perpendicular tests and the joint in 63% of angled tests, although none of these included the middle finger. CONCLUSIONS: Two micro bone anchors fit within the distal phalanx in all fingers tested, except the little finger, when placed in the perpendicular position. At a 45° angle, the distal phalanx of the little finger can also accommodate micro bone anchors without any evidence of complication when placed 4 mm from the joint. The mini anchors were too large to fit in a perpendicular position within the distal phalanx. In the 45° angled position, the joint was not penetrated by the mini anchor in only middle fingers. CLINICAL RELEVANCE: The study provides anatomical evidence of the accommodation of micro bone anchors within the distal phalanx in perpendicular or 45° angled positions for the repair of FDP tendon avulsion injury.

[Arthroscopic-assisted stabilization of medial shoulder instability in a Miniature Poodle]. / Arthroskopisch-assistierte Stabilisation einer medialen Schulterinstabilität bei einem Zwergpudel.

INTRODUCTION: A 12-year old female miniature Poodle was presented because of a 4/4 right fore-limb lameness. The orthopedic examination demonstrated pain at palpation of the right shoulder and an abduction angle of 55 °. MRI examination confirmed injuries consistent with a traumatic medial shoulder instability with no evidence of shoulder dysplasia. A partial rupture of the subscapularis tendon and complete detachment of the cranial gleno- humeral ligament were confirmed with arthroscopy. The joint was successfully stabilized using an arthroscopic assisted prosthetic suture.

[Endo-exo prostheses : Osseointegrated percutaneously channeled implants for rehabilitation after limb amputation]. / Endo-Exo-Prothesen : Osseointegrierte, perkutan ausgeleitete Implantate zur Rehabilitation nach Gliedmaßenamputation.

BACKGROUND: In 1999 the first endo-exo femoral prosthesis (EEFP) was implanted in Germany in a patient who had suffered a traumatic above-knee amputation. This procedure involves a skeletally anchored exoprosthetic device that is inserted into the residual femur. The distal part of the implant protrudes transcutaneously and allows attachment to a prosthetic limb which provides direct force transmission to the external prosthetic components. The technique originated from dental implantology and helps to avoid possible problems resulting from treatment of amputated limbs using socket prostheses. In the meantime, durability times of over 10 years have now helped to invalidate the initially well-founded reservations held against the procedure. OBJECTIVE: What advantages can be achieved by osseointegrated and percutaneously channeled prostheses and which problems had to be overcome for treatment. MATERIAL AND METHODS: Critical evaluation of data from patients operated on in Lübeck, Germany from January 2003 to December 2014. RESULTS: With osseointegrated and percutaneously channeled prostheses permanent durability times can be achieved. Infection-associated soft tissue problems at the site of skin protrusion (stoma) can be successfully prevented. The creation of this so-called stoma means acceptance of a possible bacterial portal of entry into the body. Patient satisfaction has so far been high, postoperative rehabilitation is simplified and the technique could possibly lower the costs of medical treatment. CONCLUSION: Endo-exo prostheses have proved to be successful for more than 15 years. A critical appraisal of the indications as well as a close cooperation between the surgeon, orthopedic technician and the associated rehabilitation facilities with the patient are the basis for the long-term success of this relatively new treatment approach.

A Modified Suture Bridge Technique for Application With Bone Anchors in Foot and Ankle Surgery.

We present a suture bridge technique for reattachment of tendon or ligament to bone for use in foot and ankle surgery. The method is a simple, strong, and reproducible technique that could decrease the risk of irritation of the overlying cutaneous barrier and minimizes the likelihood of tendon strangulation when combined with soft tissue bone anchors. The present report serves as a guide to the use of this suture technique for reattachment of the Achilles tendon.

Ex vivo biomechanical evaluation and comparison of lateral femoro-fabella ligament suture and lateral suture with bone anchor for cranial cruciate ligament repair in cats.

OBJECTIVE: To compare the biomechanical properties of lateral femoro-fabella ligament suture (FFLS) and lateral suture with a bone anchor suture (BAS) for management of feline cranial cruciate ligament disease. ANIMALS: 12 femurs from 6 mature cat cadavers. METHODS: The samples were collected from April to June 2023. The specimens had an FFLS and, subsequently, BAS placed and were positioned into a biomechanical testing machine, preloaded from 5 N to 15 N for 100 cycles, and subsequently, a load to suture failure was applied. The displacement at 5 N and 15 N, the total precycle displacement (millimeters), the force at 3 mm displacement and at failure (newtons), the displacement at failure (millimeters), and the stiffness to failure (Newton:millimiter) were recorded. Nonparametric Wilcoxon signed-rank tests were used to compare data between the 2 groups. RESULTS: The displacement at 5 N and 15 N and the total precycle displacement were significantly higher in the FFLS group compared to the BAS group. Additionally, the FFLS group results showed less consistent displacement and marked variability. The force (newtons) at 3 mm displacement was higher in the BAS group. There was no significant difference in force and no significant difference in displacement at failure between the 2 groups. However, the stiffness to failure (N/mm) was significantly higher in the BAS group. CONCLUSION: BAS represented a more stable and reliable femur attachment for extracapsular suture in cats. CLINICAL RELEVANCE: To demonstrate the stability and reliability between BAS and FFLS and influence implant selection in the treatment of cranial cruciate ligament rupture in cats with evaluation of biomechanical properties.

Bone Anchor Fixation in the Repair of Blunt Traumatic Abdominal Wall Hernias: A Western Trauma Association Multicenter Study.

BACKGROUND: Blunt traumatic abdominal wall hernias (TAWHs) are rare but require a variety of operative techniques to repair including bone anchor fixation (BAF) when tissue tears off bony structures. This study aimed to provide a descriptive analysis of BAF technique for blunt TAWH repair. Bone anchor fixation and no BAF repairs were compared, hypothesizing increased hernia recurrence with BAF repair. METHODS: A secondary analysis of the WTA blunt TAWH multicenter study was performed including all patients who underwent repair of their TAWH. Patients with BAF were compared to those with no BAF with bivariate analyses. RESULTS: 176 patients underwent repair of their TAWH with 41 (23.3%) undergoing BAF. 26 (63.4%) patients had tissue fixed to bone, with 7 of those reinforced with mesh. The remaining 15 (36.6%) patients had bridging mesh anchored to bone. The BAF group had a similar age, sex, body mass index, and injury severity score compared to the no BAF group. The time to repair (1 vs 1 days, P = .158), rate of hernia recurrence (9.8% vs 12.7%, P = .786), and surgical site infection (SSI) (12.5% vs 15.6%, P = .823) were all similar between cohorts. CONCLUSIONS: This largest series to date found nearly one-quarter of TAWH repairs required BAF. Bone anchor fixation repairs had a similar rate of hernia recurrence and SSI compared to no BAF repairs, suggesting this is a reasonable option for repair of TAWH. However, future prospective studies are needed to compare specific BAF techniques and evaluate long-term outcomes including patient-centered outcomes such as pain and quality of life.

Three-Dimensional Cone Beam Computed Tomography (CBCT)-Derived Soft Tissue Changes in Patients with Unilateral Cleft Lip, Alveolus, and Palate with Midfacial Deficiency after 1.5 Years of Bone-Anchored Maxillary Protraction.

Background: Bone-anchored maxillary protraction (BAMP) aims to correct midfacial deficiencies, with proven positive skeletal changes without potential unwanted side effects. However, the influence of BAMP treatment on facial soft tissues, particularly in subjects with complete unilateral cleft lip, alveolus, and palate (CUCLAP), remains unclear. Methods: This single-center longitudinal cohort study examined the effects of 1.5 years of BAMP treatment on facial soft tissues in growing subjects with complete unilateral cleft lip, alveolus, and palate. The sample consisted of 25 patients, age range 9.7 to 12.6 years. Three-dimensional surface models derived from CBCT scans were superimposed on stable structures of the anterior cranial base and on the occipital area posterior of the foramen magnum to assess three-dimensional changes due to growth and BAMP therapy. Results: The results revealed a moderate positive correlation (Pearson's correlation coefficient from 0.203 to 0.560) between changes in hard tissue and soft tissue; some correlations were found to be weak (<0.300). Linear changes in soft tissue following BAMP were in the same direction as skeletal changes, showing downward, forward, and outward displacement. The only exception was in the vertical dimension. The lower facial third showed a slight but significant reduction, mainly in lip length (-1.2 mm), whereas the middle facial third showed a small increase (1.1 mm). Conclusions: It was concluded that during BAMP, soft tissue changes occur in the same direction as skeletal changes, although with a larger variability and less pronounced effects.

Mechanical load applied by Intraosseous Transcutaneous Amputation Prosthesis (ITAP) during walking on level and sloped treadmill: A case study.

This proof of concept study presents a method to collect and analyse kinetic data from one participant with a transfemoral amputation fitted with a percutaneous osseointegrated implant walking on a level and sloped treadmill. We describe the construction of and results from a bespoke wireless six axis load cell built into one participant's prosthetic assembly. The load cell does not clinically compromise the participant in any way and is an initial milestone in the development of a light-weight wireless load cell for use with percutaneous osseointegrated implants. In this case, it is the first time that kinetic data from a participant fitted with an Intraosseous Transcutaneous Amputation Prosthesis has been published. We propose that the data can be used to model the load transfer to the host bone, with several clinically significant applications. The raw dynamic data are made available and quasi-static load cases for each functional phase of gait are presented. Peak forces obtained in the medio-lateral (X), cranio-caudal (Y) and antero-posterior (Z) axes over level ground respectively were -243.8 N (0.24 BW), 1321.5 N (1.31 BW) and -421.8 N (0.42 BW); uphill were -141.0 N (0.14 BW), 1604.2 N (1.59 BW), -498.1 N (0.49 BW); downhill were -206.0 N (0.20 BW), 1103.9 N (1.09 BW), -547.2 N (0.54 BW). The kinetics broadly followed able bodied gait patterns with some gait strategies consistent in participants with other implant designs or prosthetic socket connections, for example offloading the artificial limb downhill.

Bone anchor as fixation method for abdominal wall reconstruction. A case report about a ten times recurred inguinal hernia.

INTRODUCTION: While the use of bone anchor fixation for abdominal wall reconstruction for supra-pubic incisional hernia is well described (Yee et al., 2008 [1]), we show in this case report, written in line with the SCARE criteria (Agha et al., 2020 [2]), a novel use of this tool as an adjunct in the repair of a ten time recurrent inguinal hernia. CASE REPORT: A 65 years old multiparous, diabetic non-obese female, with previous abdominoplasty was submitted for left inguinal hernia for ten times, between multiples complications between infection, more than one mesh excision by anterior approach and laparoscopic approach. The wide range of procedures culminated in a destruction of the abdominal wall, making it impossible for a usual fixation of mesh in the region. Therefore, a multidisciplinary approach was planned for the patient with a bone anchor as a mesh fixation method. With a year follow up we did not observe a local hernia recurrence. CLINICAL DISCUSSION: Hernia itself is a multifactorial disease. As a anatomical defect, surgery is the only effective treatment. Our report brings a novel approach to a challenging case with many previous unsuccessful applications of conventional surgeries. Hence, we stimulate the multidisciplinary discussion for enhancing post operatory outcomes and a better point of care for the patient.

Novel prosthetic ligament repair of a shoulder luxation in a cat using a bone anchor and ligament prosthesis.

Case summary: A 7-year-old male castrated Ragdoll cat was presented for chronic shoulder instability after a previous medial luxation of the right shoulder. Upon examination, there was palpable instability of the glenohumeral joint and an increased abduction angle. Surgical stabilisation was elected due to lameness and instability after closed reduction, rest and medical management. A low-profile bone-anchor and a ligament prosthesis were used to stabilise the glenohumeral joint with minimal disruption to the cat's natural shoulder stabilisers. Clinical signs resolved after surgery and the cat remained non-symptomatic at the 12-month follow-up. Relevance and novel information: Feline shoulder luxation is rarely described in the veterinary literature. To the authors' knowledge, this is the first report describing stabilisation of the glenohumeral joint in a cat using a bone anchor and a ligament prosthesis.

A Comparison of Outcomes at Twelve Weeks of Traditional Button-Over-Nail versus Bone Anchor Repair of Zone I Flexor Digitorum Profundus Tendon Injury.

Background: The repair of zone 1 flexor tendon injury often relies on re-inserting the flexor digitorum profundus (FDP) tendon to the distal phalanx. The aim of this retrospective study is to compare outcomes at 12 weeks following traditional button-over-nail (BON) versus bone anchor (BA) repair of zone I FDP injury. Methods: Patients undergoing zone 1 FDP repair between April 2007 and September 2018 using a BON or a BA were included in the study. Patient demographics, complications, arc of flexion of distal (distal interphalangeal joint [DIPJ]) and proximal interphalangeal joint (PIPJ) and patient-rated outcomes were analysed. Results: Forty-three patients were included in the study: 21 in the BA group and 22 in the BON group. Good function was achieved by 20 patients in BA versus nine in BON. Complications occurred in five BA patients versus 10 BON patients. Patients achieved a mean active DIPJ flexion of 49° and 31° and PIPJ flexion of 92° and 57° in the BA and BON groups, respectively. Conclusion: Our study demonstrates better arc of motion, patient-rated outcomes and lower complications at 12 weeks after surgery in patients undergoing zone 1 FDP repair using a BA. Level of Evidence: Level III (Therapeutic).

Urethrovaginal fistula 11 years after a bone anchor sling using woven polyester and treatment with a Martius flap.

INTRODUCTION: We encountered a urethrovaginal fistula diagnosed 11 years after a bone anchor sling. CASE PRESENTATION: A 58-year-old woman underwent a bone anchor sling to treat stress urinary incontinence. At age 69, mid-urethral sling was planned because of a recurrent stress urinary incontinence diagnosis, but a urethrovaginal fistula was found immediately before the procedure. After removing woven polyester, the previous sling material, simple fistula closure was carried out but failed. Usage of a vaginal speculum and powerful medical lamps during a stress test revealed leakage from both the urethrovaginal fistula and the external urethral meatus. She underwent another fistula closure using a Martius flap. Subsequently, a 1-h pad test improved from 195 to 5.1 g/h. The remaining mild stress urinary incontinence did not necessitate further treatment. CONCLUSION: Anti-incontinence procedures using synthetic materials can cause urethrovaginal fistula. Attention must be paid to the possibility of urethrovaginal fistula when patients complain of worsened incontinence postoperatively.

Comparison of Extracapsular Stabilization Techniques Using an Ultrasonically Implanted Absorbable Bone Anchor (Weldix) after Cranial Cruciate Ligament Rupture in Cats-An In Vitro Study.

BACKGROUND: This study evaluated joint stability after surgical repair of cranial cruciate ligament (CrCL)-deficient stifle joints in cats using a novel absorbable polylactide bone anchor in an ex vivo model. METHODS: Thirty-six hindlimbs from cats with intact (Gi group) and transected CrCLs were treated with fabellotibial suture alone (GFW group), suture combined with an absorbable polylactide bone anchor (GWD group), or suture combined with a nonabsorbable bone anchor (GFT group), positioned in a limb press with predefined joint angles (stifle joint: 120 ± 5°; hock joint: 120 ± 5°) and loaded with 10%, 20%, and 30% of body mass (BM). Predefined points were measured on lateral radiographs and with a coordinate measurement machine. Distances on radiographs (mm) were measured and angles (°) were calculated to represent the craniocaudal movement and the internal rotation of the tibia. RESULTS: There were no differences for craniocaudal movement between Gi and GFW or GFT, but for GWD regarding angle measurement at 30% BM. For internal rotation, there was no significant difference between Gi and GFW or GWD, but for GFT. CONCLUSION: The used absorbable polylactide bone-anchor was able to stabilize the stifle joint regarding internal rotation and craniocaudal movement as calculated from distance measurements.

Four Anchor Repair of Jersey Finger.

Background: Various surgical techniques for treating avulsions of the flexor digitorum profundus tendon at the distal phalanx have been published but no ideal technique has emerged. We introduce a new all-internal 4-anchor flexor tendon repair technique and evaluate outcomes in three clinical cases. Methods: In this retrospective case series, we reviewed three patients that sustained an avulsion of the flexor digitorum profundus tendon at the distal phalanx. All patients were surgically treated with the four-anchor repair technique. Two titanium anchors were inserted into the distal phalanx and two all-suture anchors were inserted distal to the first set of anchors. The tendon was then attached to these four anchors using a Krackow stitch pattern and the anchors were sown to each other. Active flexion and extension of the proximal and distal interphalangeal joint were measured at 3-month, 12-month, and 5-year follow-up. Postoperative complications were documented. Results: All patients achieved excellent clinical outcomes according to assessment criteria. At 3-month follow-up, all patients regained full flexion; two patients had full extension, while one patient was 3 degrees short of full extension. At 12-month follow-up, all patients had full flexion and extension. Five-year follow-up demonstrated the same results with no loss of function, sensation or grip strength. The repairs healed without rupture, and no complications were reported. Conclusion: The 4-anchor flexor tendon repair is a viable surgical technique for zone 1 flexor digitorum profundus tendon repair or reconstruction. Further studies are needed to replicate these promising results and biomechanically validate this technique.Level of Evidence: IV.

A Comparative Study of Automatic Localization Algorithms for Spherical Markers within 3D MRI Data.

Localization of features and structures in images is an important task in medical image-processing. Characteristic structures and features are used in diagnostics and surgery planning for spatial adjustments of the volumetric data, including image registration or localization of bone-anchors and fiducials. Since this task is highly recurrent, a fast, reliable and automated approach without human interaction and parameter adjustment is of high interest. In this paper we propose and compare four image processing pipelines, including algorithms for automatic detection and localization of spherical features within 3D MRI data. We developed a convolution based method as well as algorithms based on connected-components labeling and analysis and the circular Hough-transform. A blob detection related approach, analyzing the Hessian determinant, was examined. Furthermore, we introduce a novel spherical MRI-marker design. In combination with the proposed algorithms and pipelines, this allows the detection and spatial localization, including the direction, of fiducials and bone-anchors.