Aim: The aim was to prove the efficency of the arthroscopic release of retinaculum as minimally invasive and primary surgical method in treatment of lateral habitual luxation of patella in adolescents. Majority of the patiens were sportswomen and so it was required to have smaller scaring.

Materials and Methods: Between july 2003 and july 2007, we did the arthroscopic release of the lateral retinaculum in 24 children, (21, 3) aged between 12 and 18, on 28 knees. All of them were active in different sports, e.g. football, athletics, basketball, kickboxing. The indication was set after the second to twentieth pre-operative luxation depending on when the patient came for treatment to our clinic. Retinaculotomy was always done in fluid milieu, using spinal or endotracheal anesthesia depending on the age of the child. The average postoperative follow-up was 24 months.

Results: To compare our patients we made a table, which is filled in with queries preoperatively and postoperatively about the number of luxations and subluxations, pain, mobility, axial images of patella at 60°, patient’s satisfaction and sports activity. In 26 cases we cured the luxations, lowered the painfulness and 17 children returned to their previous sports activities. In 2 cases, after continuation of sports, the luxation occured again, so we had to use additional surgical Methods: Conclusion: With this method we achieved good results with smaller scaring if we did the lateral release earlier comparing to the number of luxations and if there was no hypoplasia of lateral condil of femur.

The impact of cement leakage during percutaneous vertebroplasty has not been well characterized. This study aimed to quantify and compare cement leakage and its clinical significance in osteoporotic and metastatic vertebrae treated with vertebroplasty. Cement leakage was quantified using semi-automated thresholding of digital CT scans for fouteen metastatic and nineteen osteoporotic vertebrae and compared to pain scores. Cement leakage was present in 90.9% of vertebrae. Cement leaked predominantly into the disc in the osteoporotic vertebrae but yielded more diffuse leakage patterns in the metastatic cases. Despite cement leakage, there was significant improvement in pain immediately following vertebroplasty for all patients.

This study aimed to quantify cement leakage in osteoporotic and metastatic vertebrae post-vertebroplasty and to determine whether leakage has clinical significance at follow-up.

Despite high incidences of cement leakage, both osteoporotic and metastatic patients experienced significant immediate pain relief post-vertebroplasty.

Cement leakage is investigated as a possible rationale for the higher rates of pain relief seen in osteoporotic vs metastatic patients undergoing percutaneous vertebroplasty.

Cement leakage was present in 90.9% of the vertebrae treated. The percent volume of cement leakage was 11.6±10.6 in the osteoporotic vertebrae and 19.4±19.1 in the metastatic vertebrae (p=0.144). Cement leaked predominantly into the disc in the osteoporotic vertebrae whereas leakage was more diffuse in the metastatic vertebrae. Pain scores were high prior to vertebroplasty and decreased significantly following the procedure in both groups irrespective of leakage (p< 0.05).

Digital CT scans were retrieved for osteoporotic (n=19) and metastatic (n=14) patients treated with percutaneous vertebroplasty. Volume of cement injected directly into the vertebral body and location of cement leakage (pedicle, disc, periphery, canal) was quantified using semi-automated thresholding techniques. Pain scores were collected at four stages of treatment (pre, immediately post, one day post, one week post-vertebroplasty).

Disruption of the endplate in the osteoporotic spine provides an easily accessible pathway for the leakage of cement into the disc. Elevated pressurization during cement injection into metastatically involved vertebrae may account for the more diffuse cement leakage seen in the metastatic group. Clinically, pain scores improved irrespective of leakage.

A load cell, capable of measuring medial and lateral loads independently, was used to evaluate current methods of ligamentous balancing in total knee arthroplasty. Ten cadaveric knees were randomized with the surgeons blinded or unblinded to the load cell’s output. Before ligament resection, there were differences between medial and lateral forces (p< 0.05). Balance improved in both groups following ligamentous releases. There was a trend for superior balance (medial-lateral compressive force) with load cell feedback provided: 30°(11.1 vs. 44.4N), 60°(7.1 vs. 36.9N), and 90°(3.0 vs. 8.7N). Further in-vivo studies with this device may improve load transfer and the longevity of TKA.

The purpose of this study was to employ a tibial load cell to assess current methods of ligamentous balance during total knee arthroplasty, and to determine whether the load cell can improve load distribution between the medial and lateral compartments.

Current methods achieve imperfect load balance, however this may be improved with the assistance of an intra-operative load cell.

Intra-operative assessment and quantification of load balance with a load cell may improve the longevity of TKA.

TKA was performed on five pairs of cadaveric knees which were randomly assigned into one of two groups based upon whether the surgeons were blinded or unblinded to the load cell’s output. A validated tibial load cell, capable of measuring medial and lateral loads independently, was inserted. Compartment forces were recorded at discrete flexion angles prior to ligamentous balancing and again after soft tissue balancing with final components cemented into position.

Initially, there were significant differences between the loads in the medial and lateral compartments (p< 0.05). With soft tissue release, there was improved balance. There was a trend for superior balance (medial minus lateral compressive force) in the unblinded group at 30°: 11.1N unblinded vs. 44.4N blinded, 60°: 7.1 vs. 36.9N, and 90°: 3.0 vs. 8.7N.

Failure to achieve ligamentous balance results in instability and unequal load distribution. Current balancing techniques are not perfect, but appear to be improved with the use of the load cell. Further in-vitro and in-vivo studies are needed to improve the load distribution following TKA.

Vertebroplasty (VP) is currently used to improve spinal stability in patients with vertebral metastases. This study assessed the effects of Laser Induced Thermo Therapy (LITT), a minimally invasive technique used to ablate tumor tissue prior to vertebroplasty. Load-induced canal narrowing (LICN) was measured pre and post-vertebroplasty in twelve paired spinal motion segments with simulated lytic metastases. LICN improved post-vertebroplasty for all specimens treated with LITT. In all specimens, cement location was an important factor in post-vertebroplasty stability. Reduction of the tumor volume pre-vertebroplasty resulted in more reliable defect filling.

To investigate the effect of tumor ablation using Laser Induced Thermo Therapy (LITT) prior to vertebroplasty (VP) on cement distribution and vertebral stability.

Tumor volume reduction using LITT prior to cement injection improves defect filling and consistently reduces Load Induced Canal Narrowing (LICN).

A simple, minimally invasive procedure providing accurate tissue destruction pre-vertebroplasty may result in more reliable cement fill, reduce cement extravasation and improve post-vertebroplasty stability.

Following verebroplasty, LICN improved in all specimens treated with LITT and in those VP alone specimens with cement located posterior to the tumor tissue (33%). LITT treated vertebrae exhibited a trend toward reduced posterior wall motion post-vertebroplasty (LICN=29.7±27.1%) versus specimens treated with VP alone (LICN=248.7±253%). In the LITT+VP group, cement was fully contained within the vertebral body while cement extravasation into the canal was noted in 33% of the specimens treated without LITT.

Twelve paired cadaveric thoracolumbar spinal motion segments with simulated lytic metastases were randomized for treatment with VP alone or LITT+VP. In the LITT+VP group, a laser fibre inserted through a transpedicular approach was used to ablate the tumor tissue prior to cement injection. The specimens were axially loaded to 800N pre and post-treatment. LICN was used as a measure of vertebral stability. Cement location was assessed post-testing through axial sectioning. Location of cement is an important factor in determining post-VP stability. Vertebroplasty is effective in decreasing LICN if the tumor is ablated or surrounded posteriorly with cement.

Funding: USAMRMC DAMD 17–00–1–0693

In percutaneous vertebroplasty, clinically significant complications occur predominantly in patients with spinal metastases. This higher rate of complication may be associated with increased pressurization that has been reported due to the presence of lytic tissue during vertebroplasty. To date, there has been no research investigating techniques aimed at reducing this pressurization. This study investigated the potential of tumour volume reduction using laser induced thermo therapy ablation within the metastatic spine. This novel technique proved to be capable of efficient tissue shrinkage (average 60%) with little or no pressurization (average 1.3mmHg) and moderate levels of temperature elevation (average increase of 15.1°C).

This study aims to investigate the potential of minimally invasive tumour volume reduction using laser induced thermo therapy ablation within the metastatic spine.

Volume reduction of tumour tissue prior to cement injection may provide a method to reduce pressurization, reduce the likelihood of tumour extravasation and improve cement fill during percutaneous vertebroplasty.

In percutaneous vertebroplasty, clinically significant complications occur predominantly in patients with spinal metastases (10%).

Laser-induced thermo therapy condensed and coagulated the simulated tumour. Volume shrinkage of the tumour tissue averaged 60%. Pressures generated within the vertebral body only rose an average of 1.3mmHg during the procedure. Maximum temperatures on the posterior body wall increased by 15.1°C, with average temperatures 6.8°C above the baseline.

A simulated lytic defect created using breast tissue was introduced into the vertebral body of a calf spine to model a metastatically involved vertebra. A pre-charred surgical fibre coupled to a diode laser delivering 1750J of energy was inserted through an eleven-guage needle into the centre of the tumour using an intrapedicular technique. During treatment, the temperature at the posterior body wall and intravertebral pressure were measured. Following ablation, the volume of the remaining tissue was measured.

The results suggest that this novel technique is capable of reproducible, uniform, and effective tissue destruction with little to no pressurization and moderate levels of temperature elevation. Both pressures and temperatures generated during our study were lower than reported values during percutaneous vertebroplasty and suggest little risk of complications.

Intramedullary nailed high proximal tibial fractures rely on the proximal screw-bone interface to provide stability, which can be insufficient in low-density bones. This study investigated the biomechanics of proximal screw cement augmentation in intramedullary nailing of high proximal tibial fractures. Mechanical stability in flexion/extension, varus/valgus and torsion was tested on six pairs of cadaveric proximal tibiae, with/without cement augmentation. Cement augmentation significantly increased construct stability in torsion and demonstrated a trend towards improved varus/valgus stabilization. Surprisingly, cement augmentation significantly decreased stability in flexion/extension, suggesting the potential benefits of cement augmentation may be limited in intramedullary nailed high proximal tibial fractures.

This study assessed the biomechanical effects of augmenting proximal screws with cement in intramedullary nailing of high proximal third tibial fractures.

While increased biomechanical stability was seen in torsion and varus/valgus, the reduction in stability in flexion/extension suggests that there may be limited benefit in cement augmentation in the nailing of high proximal tibia fractures.

High proximal tibial fractures fixed with intramedullary nailing rely primarily on proximal screw fixation to provide stability. Cement augmentation of the proximal screws may provide needed increased construct stability in low-density tibiae.

Cement augmentation provided a significant increase in construct stability in torsion (37.5% ± 8.0%, p< 0.05), with a trend toward increased stability in varus/valgus (25.5% ± 36.2%, p=0.08). Conversely, stability in flex-ion/extension was significantly decreased with the use of cement (25.9% ± 13.0%, p< 0.05).

Reamed intramedullary nails (Zimmer, MDN) were implanted into six pairs of elderly cadaveric fresh-frozen proximal tibiae and secured using four proximal screws (two transverse, two oblique, 4.5mm diameter). Bone cement was injected into the screw holes just prior to screw insertion to augment the bone-screw interface in one tibia from each pair. Specimen stability was tested in flexion/extension and varus/valgus loading to 12Nm and in torsion to 7Nm. Displacement data was generated and analyzed using a repeated measures design.

We hypothesized that intramedullary nail-bone construct stability would be increased with cement augmentation, particularly in low-density specimens. While construct stability was improved in torsion and varus/valgus, surprisingly stability consistently decreased in flexion/extension.

Using serial CT scans, this project aims to develop a clinical research tool that analyzes changes in vertebral density in spines involved with metastatic disease. Tracking of total vertebral body and tumor volume alone was investigated. A program was developed to semi-automate the segmentation of the region of interest followed by image registration to superimpose the segmentation onto spatially aligned serial scans. Based on analysis of a simulated metastatic vertebra, generating a voxel distribution histogram from the vertebral body best quantified density in serial scans. This quantification method may improve clinical decision-making and treatment options for patients with vertebral metastases.

To develop a clinical research tool to serially track tumor involvement in vertebrae with metastatic disease by quantifying changes in CT attenuation.

Segmentation of the vertebral body and analysis of the voxel distribution within the region provides the most accurate method of quantifying changes in tumor involvement for the metastatic spine.

A quantitative method to assess the progression or regression of disease may improve clinical decision–making and treatment options for patients with spinal metastases.

The vertebral body segmentation was more accurate at tracking tumor involvement (voxel distribution histogram: 96.8% +/− 0.75% accuracy, mean density error: 4.7% +/− 0.8%) than segmenting the tumor volume alone (voxel distribution histogram: 86.1% +/− 3.6% accuracy, mean density error: 14.1% +/− 4.8%).

A program was developed to semi-automatically segment the total vertebral body and tumor volume alone from CT scans of metastatically involved vertebrae. Image registration through user-defined landmarks and surface matching was used to spatially align serial scans, and the initial segmentation was superimposed with the aligned scans. Changes within the segmentation between CT scans were tracked using mean density and a voxel distribution histogram. A cadaveric vertebra with a simulated tumor was scanned at five orientations with 20° offsets to determine the accuracy of the methods. Error primarily resulted from unavoidable re-sampling during alignment of the scans.

Photodynamic therapy (PDT) is a promising new treatment for spinal metastases; however, the effects of PDT on bone are largely unknown. This study assessed the impact of PDT on spinal stability in rats at high (non-therapeutic) drug and LASER light doses. Spinal stability was assessed using stereological measures attained from in vitro μCT scans. High doses of PDT were shown to cause a reduction in vertebral density. Postoperative paralysis was also noted in a subset of animals treated. Tumour-involved vertebrae are already mechanically weakened; as such it is essential to establish a safe and efficacious therapeutic window for vertebral PDT.

This study assessed the effect of high doses of photodynamic therapy (PDT) on biomechanical stability and bone density of lumbar vertebrae.

PDT can cause damage to the vertebral bone and induce paralysis when treatment is applied at very high doses in the rat spine.

PDT is a promising new treatment for spinal metastases however, it is important to understand its effect on vertebral bone in order to closely define the therapeutic window for safety and efficacy.

Trabecular bone density decreased from L1–L3 in normal, untreated rats. The L2 vertebra when treated with high dose PDT was shown to have decreased bone density as compared to both L1 and L3. As expected, tumour-bearing rats had lower vertebral densities than normals.

Rnu/Rnu rats were separated into normal controls, normals treated with PDT and tumour-bearing rats. Rats treated with PDT received an intercardiac injection of 2.5mg/Kg BPD-MA. The drug was activated through administration of 500J (300mA) of a non-thermal 690nm LASER adjacent to the L2 vertebral body. After one week, in vitro μCT scans were taken of L1–L3 and stereological quantities measured.

The demonstrated reduction of bone density as quantified one week following treatment is important when considering spinal stability in the potential use of PDT to treat vertebral metastases. We have observed that the therapy can induce paralysis when treatment is applied at high doses in the rat spine. The intermediate and long-term effects of PDT on bone remain unknown and require ongoing study.