Achilles tendon (AT) rupture may lead to complaints of heel pain. In forefoot ulcer patients AT lengthening is used to transfer pressure from forefoot to the heel. The primary aim was to investigate if AT was longer or associated with changes in pedobaric measurements, in particular heel pressure, on the injured leg 4–5 years after the injury.

Increase in heel height increases peak pressure under the forefoot. Customized shoe inlays with metatarsal lift, arch support has demonstrated lowered forefoot pressure and increase in the subjective comfort. A commercial shoe brand (Roccamore) has introduced an off-the-rack stiletto with a slim (1 cm²) 8 cm heel plus 2 cm platform with metatarsal lift, arch support and heel cap claiming it will reduce the discomfort associated with high heels. The primary aim of this study was to compare the pressure under the forefoot, arch, heel and toes in this “orthopaedic” stiletto (OS) to a standard stiletto of the same heel height without inlays (SS) and a control sneaker (SN). Secondary aims were to measure the comfort under the forefoot, heel and arch during everyday use. Finally to investigate if any pressure measurements were correlated to comfort or any anatomical/clinical feature of the foot.

22 women, aged 40 (21–62), accustomed to stilettos, walked at 4 km/hr on a level treadmill in all three shoe types. Peak pressure (kPa) and pressure-time integral (kPa/sec) under 2+3rd and first metatarsal heads, the arch/midfoot and heel were measured during 10 consecutive steps at 50 Hz using Novel Pedar-X pressure distribution insoles. Standing X-rays and a standardized clinical examination were carried out. Mundermanns comfort VAS and daily steps were recorded for each shoe type during 3 full days. (0= worst to 150 mm= most comfortable). Data were compared with paired t-tests and regression analysis. Statistical significance is reported as p<0.05=, p<0.01=, p<0.001=.

Peak pressure: Compared to SS the peak pressure under the 2+3 metatarsals was reduced to 82% in the OS and 60% in the SN. Under the first metatarsal it was reduced to 73% and 40%, respectively. Under the arch it was similar for SN and OS and 30% lower for the SS. Under the heel the OS was 27–28% lower than SS and SN.

The same reductions, as well as similarities in the arch were seen in the pressure-time integrals, although with smaller difference between OS and SS, and conversely larger reductions in the SN to 49% under 2+3 metatarsals and 43% under the first.

For forefoot, arch and heel, the comfort was rated highest for the SN and lowest for the SS. No statistical difference between OS and SS in the arch.

For each mm the second metatarsal was longer than the first, the peak pressure under MT2+3 rose 13 kPa (95%CI: 7 to 19) and the pressure time integral 3 kPa/s (1–5). No effect of first ray ROM or stability. The forefoot VAS score dropped (less comfortable) 0.3 mm for each kPa/s the pressure time integral rose under the MT2+3. Peak pressure parameters or daily steps were not statistically significantly related to the forefoot comfort.

A mass produced “orthopaedic” stiletto can reduce the pressure approaching those achieved in a sneaker and increase comfort for the user. An increase in pressure-time integral under 2+3 metatarsals increases the discomfort and the pressure is increased in index-minus feet.

The metal on metal implants was introduced without the proper stepwise introduction. The ASR resurfacing hip arthroplasty (RHA) withdrawn due to high clinical failure rates and the large diameter head THA (LDH-THA) are also widely abandoned. Early (2 year) radiostereometry studies does not support early instability as cause of failure but more likely metal wear products. A possible advantage may be maintenance of bone mineral density (BMD).

We present 5 year prospective follow up from a randomized series, aiming to report changes from baseline and to investigate links between implant micromotion, Cr & Co ions and BMD.

Patients eligible for an artificial hip were randomized to RHA, Biomet LDH-THA or standard Biometric THA. 19, 17 and 15 patients completed 5 year follow-up. All followed with BMD of the femur, acetabulum and for RHA the collum. RHA and THA with whole blood Co and Co. LDH-THA only at 5 year. RHA had marker based RSA of both components, cup only for LDH-THA. Translations were compiled to total translation (TT= √(x²+y²+z²)). Data were collected at baseline, 8 weeks, 6 months, 1, 2 and 5 years.

Statistical tests: ANCOVA for TT movement, Spearman's correlation for BMD, Cr, Co and BMI to TT at 5 years

RSA: The 5 year median (25%to75%) RHA cup translations were X=-0.00(−0.49 to 0.19) Y=0.15(−0.03 to 0.20), z=0.24(−0.42 to 0.37) and TT 0.58 (0.16 to 1.82) mm. For the LDH-THA X=−0.33(−0.90 to 0.20) Y=0.28(0.02 to 0.54), z=0.43(−1.12 to −0.19) and TT 1.06 (0.97 to 1.72) mm. The TT was statistically different (p<0.05) for the two cups. The RHA femoral component moved X=0.37(0.21 to 0.56) Y=0.02(−0.07 to 0.11), z=-0.01(−0.07 to 0.26) and TT 0.48 (0.29 to 0.60) mm at 5 years. There was no TT movement from year 2.

The mean (SD) acetabular BMD was diminished to 93(90–97)% for RHA and 97(93–99.9)% for THA, but LDH-THA maintained 99(95–103)%. Overall femoral BMD was unchanged at 5 years for all interventions, but both stemmed implants lost 17% at the calcar.

Median (25%to75%) whole-blood Cr peaked in the LDH-THA group with 1.7 (0.9 to 3.1) followed by RHA 1.2 (0.8 to 5.0) and THA with 0.5 (0.4 to 0.7)ppb.

For Co the highest levels were found in RHA with 1.6(0.8 to 4.7) followed by LDH-THA 1.2 (0.7–1.7) and THA 0.2 (0.2 to 0.6) ppb.

The only correlations above +/−0.3 for TT were the RHA femoral component with a correlation of 0.47 to BMI, 0.30 to Co and Cr. The ASR cup conversely had a negative correlation of −0.60 to BMI and again, the LDH-THA cup had a negative correlation of −0.37 to Cr.

In contrast to registered revision rates, we found significantly larger movement for the Biomet cup than the ASR cup. The metal ion levels were similar. The LDH-THA cup maintained the acetabular BMD best at 5 years, but the difference was small, we are limited by small numbers and the correlations between TT and the covariates showed no clear pattern.

The CCI mobile bearing ankle implant used at our orthopedic department 2010–2013, was abandoned due to failures and findings of bone loss at revision. The aim of this study was to a) Determine our true revision rate, b) Investigate accuracy of measuring prevalence, size and location of periprosthetic bone cysts through X-ray and CT and c) Relate these findings to implant alignment and patient reported outcome measurements (PROMs).

51 primary surgeries were performed, prior to this study 8 had been revised. Out of 43 un-revised patients, 36 were enrolled and underwent evaluation with metal artefact reduction CT-scans and conventional X-ray. They filled out 3 PROMs; SEFAS, SF-12, EQ-5D. Cyst volume larger than 0.1 ml was measured using VITREA volume tools for CT-scans and calculation of spherical volume for X-rays; using AP- and lateral projections. Location of lesions was recorded, according to their position relative to the implant. Medial-/lateral- and anterior-/posterior tilt of the implant parts was measured using IMPAX built in measuring tools, applied to AP- and lateral X-ray projection. The relation between lesions location and alignment of components was analyzed by logistic regression. Bias and ICC estimation between CT and X-ray was analyzed by mixed effect model. Log transformation was used to fit the normal distribution assumption. PROMs association to osteolytic volume was analyzed by linear- and logistic regression. P-values of 0.05 were considered statistically significant.

Finding large osteolytic lesions caused 4 additional patients to undergo revision and 7 are being monitored due to high risk of failure. Of the original 51 implants 14 have been revised. 8 cases because of osteolytic lesions and aseptic loosening (true revisions w. exchange of components or bone transplants), 3 periprosthetic fractures (2 non-traumatic fractures) and 3 cases of exostosis. The 3- and 5 year revision rate was 14% and 16% for true revisions and 17% and 27% overall. Cystic lesions were found in 81% of participants. Total cyst-volume was on average 13% larger on X-ray, however this difference was not significant (p = 0.55), with intraclass correlation being 0.66. Total cystic volume was not significantly related to PROM-scores (P 0.16–0.5). Location of cysts showed association with alignment of components (P 0.02–0.08). Mean tibia component anterior tilt was 89 degrees (SD 4). Mean medial tilt was 91 degrees (SD 3) for the tibial and 90 degrees (SD 4) for the talar component.

The implant investigated performs below standard, compared to public registries^{1, 2}that report overall 5 year revision rates at 5 – 6.5%. We obtained larger measurements from X-rays than CT, unlike previous studies comparing these modalities. Cysts were common and large. Correlation between lesion location and alignment of implant, with valgus and anterior tilt of components causing more lesions in adjacent zones, may suggest a link between implant failure and alignment of components.

Summary

Despite high revision rates, the mean two year migration of the ASR^TM cup is within an acceptable threshold. Slightly higher migration rates found for the M2a- Magnum™ Porous Coated Acetabular Component but longer follow up is needed to establish if this implant is at risk.

Inserting screws into the vertebral pedicles is a challenging step in spinal fusion and scoliosis surgeries. Errors in placement can lead to neurological complications. The more experienced the surgeon, the better the accuracy of the screw placement. A physical training system would provide residents with the feel of performing pedicle cannulation before operating on a patient. The proposed system consists of realistic bone models mimicking the geometry and material properties of typical patients, coupled with a force feedback probe. The purpose of the present study was to determine the forces encountered during pedicle probing to aid in the development of this training system.

We performed two separate investigations: [1] 15 participants (9 expert surgeons, 3 fellows and 3 residents) were asked to press a standard pedicle awl three times onto a mechanical scale, blinded to the force, demonstrating what force they would apply during safe pedicle cannulation and during unsafe cortical breach; [2] three experienced surgeons used a standard pedicle awl fitted with a one-degree of freedom load cell to probe selected thoracolumbar vertebrae of eight cadaveric specimens to measure the forces required during pedicle cannulation and deliberate breaching. A total of 42 pedicles were tested.

Both studies had wide variations in the results, but were in general agreement. Cannulation (safe) forces averaged approximately 90 N (20 lb) whereas breach (unsafe) forces averaged approximately 135–155 N (30–35 lb). The lowest average forces in the cadaveric study were for pedicle cannulation, averaging 86 N (range, 23–125 N), significantly lower (p<0.001) than for anterior breach (135 N; range, 80–195 N); medial breach (149 N; range, 98–186 N) and lateral breach (157 N; range, 114–228 N). There were no significant differences between the breach forces (p>0.1). Cannulation forces were on average 59% of the breach forces (range, 19–84%) or conversely, breach forces were 70% higher than cannulation forces.

To our knowledge, these axial force data are the first available for pedicle cannulation and breaching. A large range of forces was measured, as is experienced clinically. Additional testing is planned with a six-degree-of-freedom load cell to determine all of the forces and moments involved in cannulation and breaching, throughout the thoracolumbar spine. These results will inform the development of a realistic bone model as well as a breach prediction algorithm for a physical training system for spine surgery.

Introduction

Metal on metal articulations produce chromium (Cr) and cobalt (Co) debris, particularly when the articulations are worn in. High levels in the peripheral blood are indicative of excess wear and may cause adverse effects. The present RCT investigates metal ion levels and the relationship of Co, Cr ions and lymphocyte counts during the running-in period.