Olav A. Foss

Lower Risk of Revision With Patellar Tendon Autografts Compared With Hamstring Autografts A Registry Study Based on 45,998 Primary ACL Reconstructions in Scandinavia

Background: A number of studies have found comparable results after anterior cruciate ligament (ACL) reconstruction with patellar tendon autografts and hamstring autografts; however, few studies have been large enough to reveal differences in risk of revision with regard to clinical and demographic factors. Purpose: To present the distribution of grafts for ACL reconstruction based on data in the Scandinavian ACL registries and to compare the risk of revision between patellar tendon autografts and hamstring autografts. Potential associations with other clinical and demographic factors were also explored. Study design: Cohort study; Level of evidence, 2. Methods: A total of 45,998 primary ACL reconstructions, including 6736 patellar tendon autografts and 38,666 hamstring autografts, were identified in the Scandinavian ACL registries. The overall median follow-up time was 3 years (range, 0-8 years). To compare the risk of revision between groups of patients, univariate Kaplan-Meier analysis (with log-rank test) and the Cox proportional hazard regression model were applied. The hazard rate ratio with 95% CI was reported as a measure of effect. Results: Patellar tendon and hamstring autografts were used in 14.6% and 84.1% of the patients, respectively. The remaining patients received allografts, direct sutures, or other graft types (1.3%). The primary ACL injury occurred during soccer, team handball, or alpine activities in 67.5% of the patients in the patellar tendon group and 66.2% in the hamstring group. A total of 156 patients in the patellar tendon group and 1042 patients in the hamstring group underwent revision. The overall risk of revision was significantly lower in the patellar tendon group versus the hamstring group (hazard rate ratio = 0.63; 95% CI, 0.53-0.74), and it decreased with increasing age at surgery, although not strictly linearly. The lower risk of revision in the patellar tendon group was consistently observed across subgroups of patient sex, age, and concomitant cartilage injury (P > .05, test for interaction) but seemed to be slightly more pronounced for patients injured during certain pivoting activities (soccer, team handball, and alpine activities) compared with other activities (hazard rate ratio = 0.57 vs 0.81; P = .058, test for interaction). Conclusion: The majority of primary ACL reconstructions in Scandinavia are performed with hamstring autografts. Results from the present large prospective study show that patients receiving patellar tendon autografts have a statistically significantly lower risk of revision compared with patients receiving hamstring autografts.

1–year follow–up of 920 hip and knee arthroplasty patients after implementing fast–track

Background — Fast–track has become a well–known concept resulting in improved patient satisfaction and postoperative results. Concerns have been raised about whether increased efficiency could compromise safety, and whether early hospital discharge might result in an increased number of complications. We present 1–year follow–up results after implementing fast–track in a Norwegian university hospital. Methods — This was a register–based study of 1,069 consecutive fast–track hip and knee arthroplasty patients who were operated on between September 2010 and December 2012. Patients were followed up until 1 year after surgery. Results — 987 primary and 82 revision hip or knee arthroplasty patients were included. 869 primary and 51 revision hip or knee patients attended 1–year follow–up. Mean patient satisfaction was 9.3 out of a maximum of 10. Mean length of stay was 3.1 days for primary patients. It was 4.2 days in the revision hip patients and 3.9 in the revision knee patients. Revision rates until 1–year follow–up were 2.9% and 3.3% for primary hip and knee patients, and 3.7% and 7.1% for revision hip and knee patients. Function scores and patient–reported outcome scores were improved in all groups. Interpretation — We found reduced length of stay, a high level of patient satisfaction, and low revision rates, together with improved health–related quality of life and functionality, when we introduced fast–track into an orthopedic department in a Norwegian university hospital.

Periprosthetic bone loss after insertion of an uncemented, customized femoral stem and an uncemented anatomical stem: A randomized DXA study with 5-year follow-up

Background and purpose Customized femoral stems are designed to have a perfect fit and fill in the femur in order to achieve physiological load transfer and minimize stress shielding. Dual-energy X-ray absorptiometry (DXA) is regarded as an accurate method for detection of small alterations in bone mineral density (BMD) around hip prostheses. We present medium-term DXA results from a randomized study comparing a customized and an anatomical femoral stem. Methods 100 hips were randomized to receive either the anatomical ABG-I stem or the Unique customized femoral stem, both uncemented. DXA measurements were conducted postoperatively and after 3, 6, 12, 24, 36, and 60 months, and BMD was computed for each of the 7 Gruen zones in the proximal femur. Results Results from 87 patients were available for analysis. 78 completed the 5-year follow-up: 35 patients in the ABG group and 43 patients in the Unique group. In both groups, we found the greatest degree of bone loss in the proximal Gruen zones. In zone 1, there was 15% reduction in BMD in the ABG-I group and 14% reduction in the Unique group. In zone 7, the reduction was 28% in the ABG-I group and 27% in the Unique group. The only statistically significant difference between the groups was found in Gruen zone 4, which is distal to the tip of the stem, with 1.6% reduction in BMD in the ABG-I group and 9.7% reduction in the Unique group (p = 0.003). Interpretation 5-year DXA results showed that because of stress-shielding, proximal bone loss could not be avoided—either for the anatomical ABG-I stem or for the customized Unique stem.

Biomechanical femoral neck fracture experiments—A narrative review

INTRODUCTION Orthopaedic implants can be introduced in clinical practice if equivalency to an already approved implant can be demonstrated. A preclinical laboratory test can in theory provide the required evidence. Due to the lack of consensus on the optimum design of biomechanical experiments, setups vary considerably. This review aims to make femoral neck fracture models more accessible for evaluation to orthopaedic surgeons without any particular background in biomechanics. Additionally, the clinical relevance of the different setups is discussed. METHODS This is a narrative review based on a non-systematic search in PubMed, Scopus and Cochrane. SUMMARY Biomechanical femoral neck fracture experiments should aim at optimizing the recreation of the in vivo situation. The bone quality of the experimental femurs should resemble the hip fracture population, hence cadaveric bones should be preferred to the available synthetic replica. The fracture geometry must be carefully selected to avoid bias. The load applied to the specimen should result in forces within the range of in vivo measured values and the magnitude should be related to the actual weight of the donor. A well designed biomechanical experiment can prevent harmful devices from being introduced in clinical practice, however, positive results can never exclude the necessity of subsequent clinical studies.

In vitro testing of the deformation pattern and initial stability of a cementless stem coupled to an experimental femoral head, with increased offset and altered femoral neck angles:

The ability to vary femoral offset and neck angles in total hip arthroplasty increases the amount of flexibility in the mechanical reconstruction of the hip joint. The present study investigates the changes in strain pattern and bone–implant micromotion caused by increased femoral offset in combination with retroversion or reduced neck–shaft angle, made possible by a large experimental femoral head. A cementless femoral stem was inserted in 10 human cadaver femurs. Three femoral head configurations were tested: the standard situation, an increased offset combined with retroversion, and increased offset combined with reduced neck–shaft angle. The femurs were loaded in a hip simulator that was able to reproduce the conditions that correspond to one-legged stance and stair climbing. There was a statistically significant increase in strain for the experimental head at several strain gauge rosettes compared to the standard head. The largest significant increase in strain was 14.2 per cent on the anterior side of the femur. The largest mean total point motion was 44 µm in the distal coating area for the configuration with increased femoral offset and retroverted neck axis. The clinical relevance of the changes in strain distribution is uncertain. The femoral stem showed excellent initial stability for all test situations.

A biomechanical comparison of composite femurs and cadaver femurs used in experiments on operated hip fractures

Fourth generation composite femurs (4GCFs, models #3406 and #3403) simulate femurs of males <80 years with good bone quality. Since most hip fractures occur in old women with fragile bones, concern is raised regarding the use of standard 4GCFs in biomechanical experiments. In this study the stability of hip fracture fixations in 4GCFs was compared to human cadaver femurs (HCFs) selected to represent patients with hip fractures. Ten 4GCFs (Sawbones, Pacific Research Laboratories, Inc., Vashon, WA, USA) were compared to 24 HCFs from seven females and five males >60 years. Proximal femur anthropometric measurements were noted. Strain gauge rosettes were attached and femurs were mounted in a hip simulator applying a combined subject-specific axial load and torque. Baseline measurements of resistance to deformation were recorded. Standardized femoral neck fractures were surgically stabilized before the constructs were subjected to 20,000 load-cycles. An optical motion tracking system measured relative movements. Median (95% CI) head fragment migration was 0.8mm (0.4 to 1.1) in the 4GCF group versus 2.2mm (1.5 to 4.6) in the cadaver group (p=0.001). This difference in fracture stability could not be explained by observed differences in femoral anthropometry or potential overloading of 4GCFs. 4GCFs failed with fracture-patterns different from those observed in cadavers. To conclude, standard 4GCFs provide unrealistically stable bone-implant constructs and fail with fractures not observed in cadavers. Until a validated osteopenic or osteoporotic composite femur model is provided, standard 4GCFs should only be used when representing the biomechanical properties of young healthy femurs.

Muscular strength after total hip arthroplasty: A prospective comparison of 3 surgical approaches

Background and purpose — Minimizing the decrease in muscular strength after total hip arthroplasty (THA) might allow patients to recover faster. We evaluated muscular strength in patients who were operated on using 3 surgical approaches. Patients and methods — In a prospective cohort study, 60 patients scheduled for primary THA were allocated to the direct lateral, posterior, or anterior approach. Leg press and abduction strength were evaluated 2 weeks or less preoperatively, 2 and 8 days postoperatively, and at 6-week and 3-month follow-up. Results — Differences in maximal strength change were greatest after 2 and 8 days. The posterior and anterior approaches produced less decrease in muscular strength than the direct lateral approach. 6 weeks postoperatively, the posterior approach produced greater increase in muscular strength than the direct lateral approach, and resulted in a greater increase in abduction strength than the anterior approach. At 3-month follow-up, no statistically significant differences between the groups were found. The operated legs were 18% weaker in leg press and 15% weaker in abduction than the unoperated legs, and the results were similar between groups. Interpretation — The posterior and anterior approaches appeared to have the least negative effect on abduction and leg press muscular strength in the first postoperative week; the posterior approach had the least negative effect, even up to 6 weeks postoperatively. THA patients have reduced muscle strength in the operated leg (compared to the unoperated leg) 3 months after surgery.

Perioperative local infiltration anesthesia with ropivacaine has no effect on postoperative pain after total hip arthroplasty.

Background and purpose — The local infiltration analgesia (LIA) technique has been widely used to reduce opioid requirements and to improve postoperative mobilization following total hip arthroplasty (THA). However, the evidence for the efficacy of LIA in THA is not yet clear. We determined whether single-shot LIA in addition to a multimodal analgesic regimen would reduce acute postoperative pain and opioid requirements after THA. Patients and methods — 116 patients undergoing primary THA under spinal anesthesia were included in this randomized, double-blind, placebo-controlled trial. All patients received oral opioid-sparing multimodal analgesia: etoricoxib, acetaminophen, and glucocorticoid. The patients were randomized to receive either 150 mL ropivacaine (2 mg/mL) and 0.5 mL epinephrine (1 mg/mL) or 150 mL 0.9% saline. Rescue analgesic consisted of morphine and oxycodone as needed. The primary endpoint was pain during mobilization in the recovery unit. Secondary endpoints were pain during mobilization on the day after surgery and total postoperative opioid requirements on the first postoperative day. Results — The levels of pain during mobilization—both in the recovery unit and on the day after surgery—and consumption of opioids on the first postoperative day were similar in the 2 groups. Interpretation — LIA did not provide any extra analgesic effect after THA over and above that from the multimodal analgesic regimen used in this study.

The effect of interlocking parallel screws in subcapital femoral-neck fracture fixation: a cadaver study

BACKGROUND A new locking-plate for femoral-neck fractures that provides angular stability to three screws in an inverted triangle configuration was evaluated. The plate is not fixed to the lateral cortex and therefore represents a new treatment principle. METHODS Twelve pairs of cadaver femurs (mean T-score -1,95 (range -4,5-0)) with subcapital femoral-neck fractures angulating 60° were randomly allocated to fracture-fixation using either three individual screws or three interlocked screws. Subject-specific axial force and torque were applied by a hip simulator and three-dimensional migrations were recorded. The femurs underwent 10,000 cycles of simulated partial weight-bearing, followed by 10,000 cycles of simulated full weight-bearing and stair climbing. FINDINGS On average interlocking reduced femoral-head centre migrations 1.6mm (95% CI 0.1-3.1, P = 0.04). The intra-pair correlation of migration was 0.953 (Pearsons r). Interlocking did not change rotational stability (P = 0.87). Adding a locking plate did not affect the risk of failure, however all failed femurs were fixed using the smallest-sized aiming guide. INTERPRETATIONS Adding a lateral interlocking plate to three screws might improve the fracture stability. However, none of the implants were able to resist the unwanted deformation of the proximal femur. Regardless of the fixation, female sex, reduced bone quality and small sized femurs appear to increase risk of failure.

Pre-Treatment Deep Curettage Can Significantly Reduce Tumour Thickness in Thick Basal Cell Carcinoma While Maintaining a Favourable Cosmetic Outcome When Used in Combination with Topical Photodynamic Therapy

Topical photodynamic therapy (PDT) has limitations in the treatment of thick skin tumours. The aim of the study was to evaluate the effect of pre-PDT deep curettage on tumour thickness in thick (≥2 mm) basal cell carcinoma (BCC). Additionally, 3-month treatment outcome and change of tumour thickness from diagnosis to treatment were investigated. At diagnosis, mean tumour thickness was 2.3 mm (range 2.0–4.0). Pre- and post-curettage biopsies were taken from each tumour prior to PDT. Of 32 verified BCCs, tumour thickness was reduced by 50% after deep curettage (P ≤ 0.001). Mean tumour thickness was also reduced from diagnosis to treatment. At 3-month followup, complete tumour response was found in 93% and the cosmetic outcome was rated excellent or good in 100% of cases. In conclusion, deep curettage significantly reduces BCC thickness and may with topical PDT provide a favourable clinical and cosmetic short-term outcome.