Ilona M. Punt

Submicron sized ultra-high molecular weight polyethylene wear particle analysis from revised SB Charité III total disc replacements

Submicron sized particles are frequently observed in retrieved total hip and knee periprosthetic tissues and appear to be critical in the activation of the phagocytic inflammatory response. In this paper the concentration, size and shape of ultra-high molecular weight polyethylene (UHMWPE) wear particles between 0.05 and 2.00μm were determined after isolation from periprosthetic tissues from retrieved lumbar SB Charité III total disc replacements (TDR) using scanning electron microscopy (SEM). For comparison, UHMWPE wear particles were isolated from γ-radiation-air sterilized total hip arthroplasty (THA) revision tissues. The mean concentration of UHMWPE particles in TDR tissues was 1.6×10(9)g(-1)tissue (range 1.3-2.0), which was significantly lower than the concentration of 2.3×10(9)g(-1) THA revision tissue (range 1.8-3.2) (P=0.03). The mean particle size (equivalent circular diameter: TDR, 0.46μm; THA 0.53μm, P=0.60) and mean shape were comparable between TDR and THA (aspect ratio: TDR, 1.89; THA, 1.99, P=0.35; roundness: TDR, 0.58; THA, 0.56, P=0.35). However, the TDR particles tended to be smaller and more round. Although no correlations were found between visible damage to the UHMWPE core and the concentration or shape of the UHMWPE particles, a positive correlation was found between increasing particle size and increasing rim penetration of the TDR core (P=0.04). The presence of UHMWPE particles of similar size and shape in TDR tissue, albeit lower in concentration, might explain why, unlike THA, pain rather than osteolysis is the major reason for revision surgery.

Retrieval analysis of motion preserving spinal devices and periprosthetic tissues

This article reviews certain practical aspects of retrieval analysis for motion preserving spinal implants and periprosthetic tissues as an essential component of the overall revision strategy for these implants. At our institution, we established an international repository for motion-preserving spine implants in 2004. Our repository is currently open to all spine surgeons, and is intended to be inclusive of all cervical and lumbar implant designs such as artificial discs and posterior dynamic stabilization devices. Although a wide range of alternative materials is being investigated for nonfusion spine implants, many of the examples in this review are drawn from our existing repository of metal-on-polyethylene, metal-on-metal lumbar total disc replacements (TDRs), and polyurethane-based dynamic motion preservation devices. These devices are already approved or nearing approval for use in the United States, and hence are the most clinically relevant at the present time. This article summarizes the current literature on the retrieval analysis of these implants and concludes with recommendations for the development of new test methods that are based on the current state of knowledge of in vivo wear and damage mechanisms. Furthermore, the relevance and need to evaluate the surrounding tissue to obtain a complete understanding of the biological reaction to implant component corrosion and wear is reviewed.

Wii Fit™ exercise therapy for the rehabilitation of ankle sprains: Its effect compared with physical therapy or no functional exercises at all.

Lateral ankle sprains represent the most common sports‐related injuries. The Nintendo Wii Fit™ could be useful in the treatment of ankle sprains. The aim of this study was to compare the effectiveness of exercise training using the Wii Fit™ in ankle sprain patients: (a) with physical therapy; and (b) a control group not receiving any treatment. Ninety lateral ankle sprain patients were randomized to a Wii Fit™, physical therapy, or control group. We assessed the following outcome measures before, and 6 weeks after starting the allocated treatment: Foot and Ankle Ability Measure, pain during rest and walking, delay before return to sport, patient satisfaction, and effectiveness of the allocated treatment. Six weeks after the baseline measures, foot and ankle ability scores had improved in all groups, and pain had decreased during walking (P < 0.050). No between‐group differences were detected between Wii Fit™ treatment, and both other groups (P > 0.050). In conclusion, the Wii Fit™ could be used as an exercise therapy to treat ankle sprain patients. However, Wii Fit™ was not more effective than only physical therapy, or no exercise therapy at all. Patients who did not receive treatment showed similar results as people who got any kind of exercise therapy.

Gait and Physical Impairments in Patients With Acute Ankle Sprains Who Did Not Receive Physical Therapy

To assess ankle function 4 weeks after conservative management and to examine the correlation of function with gait.

Are periprosthetic tissue reactions observed after revision of total disc replacement comparable to the reactions observed after total hip or knee revision surgery

Study Design. Comparative study. Objective. To compare periprosthetic tissue reactions observed after total disc replacement (TDR), total hip arthroplasty (THA), and total knee arthroplasty (TKA) revision surgery. Summary of Background Data. Prosthetic wear debris leading to particle disease, followed by osteolysis, is often observed after THA and TKA. Although the presence of polyethylene (PE) particles and periprosthetic inflammation after TDR has been proven recently, osteolysis is rarely observed. The clinical relevance of PE wear debris in the spine remains poorly understood. Methods. The number, size, and shape of PE particles, as well as quantity and type of inflammatory cells in periprosthetic tissue retrieved during CHARITÉ TDR (n = 22), THA (n = 10), and TKA (n = 4) revision surgery were compared. Tissue samples were stained with hematoxylin/eosin and examined by using light microscopy with bright field and polarized light. Results. After THA, large numbers of PE particles of size less than 6 &mgr;m were observed, which were mainly phagocytosed by macrophages. The TKA group had a broad size range with many larger PE particles and more giant cells. In TDR, the size range was similar to that observed in TKA. However, the smallest particles were the most prevalent with 75% of the particles being less than 6 &mgr;m, as seen in revision THA. In TDR, both macrophages and giant cells were present with a higher number of macrophages. Conclusion. Both small and large PE particles are present after TDR revision surgery compatible with both THA and TKA wear patterns. The similarities between periprosthetic tissue reactions in the different groups may give more insight into the clinical relevance of PE particles and inflammatory cells in the lumbar spine. The current findings may help to improve TDR design as applied from technologies previously developed in THA and TKA with the goal of a longer survival of TDR.

Clinical, radiological, histological and retrieval findings of Activ-L and Mobidisc total disc replacements: a study of two patients

IntroductionThis study evaluates the short-term clinical outcome, radiological, histological and device retrieval findings of two patients with second generation lumbar total disc replacement (TDR).Materials and methodsThe first patient had a single level L4-L5 Activ-L TDR, the second patient a L4-L5 Mobidisc and L5-S1 Activ-L TDR. The TDRs were implanted elsewhere and had implantation times between 1.3 and 2.8 years.ResultsPlain radiographs and CT-scanning showed slight subsidence of the Activ-L TDR in both patients and facet joint degeneration. The patients underwent revision surgery because of recurrent back and leg pain. After removal of the TDR and posterolateral fusion, the pain improved. Histological examination revealed large ultrahigh molecular weight polyethylene (UHMWPE) particles and giant cells in the retrieved tissue surrounding the Mobidisc. The particles in the tissue samples of the Activ-L TDR were smaller and contained in macrophages. Retrieval analysis of the UHMWPE cores revealed evidence of minor adhesive and abrasive wear with signs of impingement in both TDR designs.ConclusionAlthough wear was unrelated to the reason for revision, this study demonstrates the presence of UHMWPE particles and inflammatory cells in second generation TDR. Long-term follow-up after TDR is indicated for monitoring wear and implant status.

Assessment of bone graft incorporation by 18 F-fluoride positron-emission tomography/ computed tomography in patients with persisting symptoms after posterior lumbar interbody fusion

BackgroundPosterior lumbar interbody fusion (PLIF) is a method that allows decompression of the spinal canal and nerve roots by laminectomy combined with fusion by means of intervertebral cages filled with bone graft and pedicle screw fixation. Conventional imaging techniques, such as plain radiography and computed tomography (CT), have limitations to assess bony fusion dynamics.MethodsIn 16 PLIFs of 15 patients with persisting symptoms, positron-emission tomography (PET)/CT scans were made 60 min after intravenous administration of 156 to 263 MBq of 18 F-fluoride, including 1-mm sliced, high-dose, non-contrast-enhanced CT scanning. Maximal standard uptake values (SUVmax) of various regions were calculated and correlated with abnormalities on CT.ResultsSubsidence of the cages into the vertebral endplates was the most frequently observed abnormality on CT (in 16 of 27 or 59% of evaluable endplates). Endplate SUVmax values were significantly higher for those patients with pronounced (p < 0.0001) or moderate (p < 0.013) subsidence as compared to those with no subsidence. Additionally, a significant correlation between vertebral and ipsilateral pedicle screw entrance SUVmax values (p < 0.009) was found, possibly indicating posterior transmission of increased bone stress. In our patient group, intercorporal fusion was seen on CT in 63% but showed no correlation to intercorporal SUVmax values.ConclusionsWith the use of 18 F-fluoride PET/CT, intervertebral cage subsidence appeared to be a prominent finding in this patient group with persisting symptoms, and highly correlating with the degree of PET hyperactivity at the vertebral endplates and pedicle screw entry points. Further study using 18 F-fluoride PET/CT should specifically assess the role of metabolically active subsidence in a prospective patient group, to address its role in nonunion and as a cause of persisting pain.

Predictability of spontaneous thoracic curve correction after anterior thoracolumbar correction and fusion in adolescent idiopathic scoliosis. A retrospective study on a consecutive series of 29 patients with a minimum follow-up of 2 years

BACKGROUND CONTEXT According to the Lenke classification, a Type 5 adolescent idiopathic scoliosis can be surgically treated with selective anterior thoracolumbar or lumbar fusion. PURPOSE This study aims to predict the spontaneous correction of the unfused thoracic curve after anterior thoracolumbar fusion and to study whether age is of influence on this predictability. STUDY DESIGN Retrospective study on a consecutive series of patients. PATIENT SAMPLE Of a consecutive series of 38 patients with idiopathic thoracolumbar scoliosis, Lenke type 5, 29 patients were included in the study. All patients were treated with anterior spinal fusion and instrumentation. A minimum follow-up of 2 years was available for all patients (mean, 4 years; range, 2-17 years). To investigate the influence of age on the outcome, we divided the group into two subgroups: an adolescent (n=13) and an adult age group (n=16). The mean age in the adolescent group was 17 (range, 13-21 years) and 38 years (range, 22-54 years) in the adult group. OUTCOME MEASURES Physiological measures include coronal Cobb angle, apical vertebral translation (AVT) and apical vertebral rotation (AVR), shoulder tilt, trunk shift, L4 tilt, and pelvic tilt. Relative corrections were computed for the thoracolumbar and thoracic curves in each patient using the following formula: (preoperative curve-postoperative curve)/preoperative curve×100 (%). The correlation coefficient between the relative (%) corrections of the thoracic and thoracolumbar curves was calculated for the whole group as for the two age subgroups. METHODS For radiographic evaluation, we used standing anteroposterior and lateral projections of the thoracolumbar spine to determine Cobb angle, AVT and AVR, and coronal balance. RESULTS Both the thoracolumbar and thoracic curves in the whole group improved after surgery (45% and 19%, respectively, p<.01). In the adolescent age group, a significant correlation between the relative (%) correction of the thoracolumbar curve and the relative (%) correction of the thoracic curve was found (R=0.704; p=.01) and between age and relative (%) correction of the thoracic curve (R=-0.805; p<.01). CONCLUSIONS These results show that the spontaneous correction of the thoracic curve is a reflection of the thoracolumbar curve correction in adolescent thoracolumbar idiopathic scoliosis. Moreover, the predictability of the thoracic curve correction in the individual patient seems to decrease with increasing age of the patient.

Neuromuscular Control Mechanisms During Single-Leg Jump Landing in Subacute Ankle Sprain Patients: A Case Control Study

Optimal neuromuscular control mechanisms are essential for preparing, maintaining, and restoring functional joint stability during jump landing and to prevent ankle injuries. In subacute ankle sprain patients, neither muscle activity nor kinematics during jump landing has previously been assessed.

Effect of Wii Fit™ exercise therapy on gait parameters in ankle sprain patients: A randomized controlled trial

Ankle sprains are the most common sport related injuries. An alternative to physical therapy in the treatment of ankle sprains is home based exercise therapy. This study aims to compare the effectiveness of Wii Fit™ exercise therapy in ankle sprain patients on temporal-spatial and kinematic gait parameters with a) conventional therapy and b) a control group not receiving exercise therapy. Ninety patients were randomly assigned to a Wii Fit™, physical therapy or control group. Temporal-spatial and kinematic gait parameters were assessed at baseline, 6 weeks and 6 months follow-up. All groups improved gait speed, cadence and step length between baseline and 6-week follow-up (P<0.036). Single support time improved only in the Wii Fit™ group (P<0.001). Symmetry index of the single support time improved in the Wii Fit™ group and physical therapy group (P<0.048). No between-group differences were found for temporal-spatial gait parameters (P>0.050). Maximum plantar flexion improved in the physical therapy and control group between baseline and 6-week follow-up (P<0.035). However, none of the groups improved dorsiflexion (P>0.050). In conclusion, an unsupervised home-based 6-week Wii Fit™ exercise therapy can be applied in ankle sprain patients. However, it was not more effective compared to physical therapy or no exercise therapy at all.