C.W. Jones

Stress relaxation and creep: viscoelastic properties of common suture materials used for flexor tendon repair.

PURPOSE The time-dependent mechanical behavior of common suture materials may have a pronounced influence on the quality of flexor tendon repairs with respect to gap formation. METHODS Sutures commonly used in plastic surgery, particularly for hand tendon repair, were tested in tension for analysis of stress relaxation and creep properties. The three materials tested were (1) Prolene, a monofilament polypropylene(Ethicon, Somerville, NJ); (2) Ethilon, a monofilament nylon(Ethicon, Somerville, NJ); and (3) Ticron, a braided polyester fiber (Sherwood, Davis & Geck, St. Louis, MO). All measurements were made with 1.5-mm (4-0) varieties of the sutures, in physiological buffered solution (0.9% phosphate-buffered saline [PBS]) at both room (22 degrees C) and body temperature (37 degrees C) conditions. RESULTS Ticron was the stiffest suture at both room and body temperature, followed by Prolene and Ethilon. Both Prolene and Ethilon showed statistically (p< .05) reduced stiffness at body temperature. Prolene exhibited statistically larger (p< .05) relaxation and creep ratios than the other two sutures, and it was the only material to show temperature effects in creep and relaxation. CONCLUSIONS Based on static and viscoelastic mechanical properties, Ticron is the most suitable suture for flexor tendon repairs when compared to Prolene and Ethilon.

HISTOLOGICAL ASSESSMENT OF THE CHONDRAL AND CONNECTIVE TISSUES OF THE KNEE BY CONFOCAL ARTHROSCOPE

Conventional histological assessment of tissue requires the removal of tissue from its physiological environment for pathological processing. In this study we report on the development and application of a laser scanning confocal arthroscope (LSCA) capable of in situ histological assessment by confocal microscopy. The knee joints of three euthanasied adult Merino sheep were imaged using the LSCA and a combination of fluorescent contrasting agents. LSCA images of various tissues were examined for common histological characteristics. The confocal histology images from the ovine knee acquired during the course of our study illustrated some of the major histological features of chondral and connective tissues. Our study demonstrates the efficacy of the LSCA for the histological assessment of the chondral and connective tissues of the ovine knee. The LSCA provides an easy and rapid method for assessing the in situ structure of cartilage, muscle, tendon, ligament, meniscus and synovium in their native and unaltered physiological environment. By obviating the need for mechanical biopsy, the LSCA provides a method for the non-destructive assessment of the chondral and connective tissues of the knee, and may be of great benefit in the investigation of orthopedic diseases or in the assessment of newly emerging cartilage repair techniques.

Quantification of Chondrocyte Morphology by Confocal Arthroscopy

The purpose of this study was to determine the effectiveness of a novel Laser Scanning Confocal Arthroscope (LSCA) for the morphological quantification of articular cartilage chondrocytes. Healthy and debrided regions of the knee articular cartilage of six (6) New Zealand White rabbits were imaged during open follow-up surgery. Quantitative morphological analysis of chondrocyte cell populations was performed and compared to known parameters. Optical histology images were compared to conventional histology of similar sites. Optical histology revealed viable cells in normal hyaline cartilage tissue and enabled the visualization of fibro-cartilage in defect tissue. Morphological analysis was able to characterize the in vivo two-dimensional equivalent-area-diameter of chondrocytes. Significant differences (P<0.05) were seen between the morphology of chondrocytes observed in optical and conventional histology. This study concludes that the LSCA is capable of illustrating the surface and sub-surface appearance of healthy and defect articular cartilage, thereby providing a non-destructive method for assessing cartilage condition in vivo. In this role the LSCA may find application in the investigation of cartilage pathologies or repair techniques.

Incidence of an Anomalous Course of the Palmar Cutaneous Branch of the Median Nerve During Volar Plate Fixation of Distal Radius Fractures

PURPOSE Volar plating of distal radius fractures using an approach through the flexor carpi radialis (FCR) sheath is commonplace. The palmar cutaneous branch of the median nerve (PCB) is considered to run in a position adjacent to, but outside, the ulnar FCR sheath. Anatomic studies have not identified anatomic abnormalities relevant to volar plating. The purpose of this study was to determine the frequency of anomalous PCB branches entering the FCR sheath during volar plating. METHODS This observational study involved 10 attending hand surgeons during a 7-month period (July 2015-January 2016). Surgeons assessed, documented, and reported any PCB anomalies that were encountered during volar plating through a trans-FCR approach. RESULTS There were 182 volar plates applied that made up the study group. There were 10 cases (5.5%) of anomalous PCBs entering the FCR sheath. In 4 cases, the PCB pierced the radial FCR sheath proximally, crossed beneath the tendon, and traveled distally on the ulnar side. In 4 other cases, the PCB entered the FCR sheath proximally on the ulnar or central aspect of the sheath and remained within the sheath, staying along the ulnar or dorsal side of the tendon. In 1 case, the PCB pierced the ulnar distal aspect of the sheath and split into 2 branches. In 1 case, the PCB ran within the sheath along the radial aspect of the FCR. CONCLUSIONS Anomalies in the course of the PCB are more common than often considered. These variants are at risk during volar surgical approaches to the wrist that proceed through the FCR sheath. CLINICAL RELEVANCE Although dissecting along the radial side of the FCR sheath may protect the PCB in most cases, care must be taken to identify anomalous branches (if present) and protect them during surgery.

Charcot arthropathy presenting with primary bone resorption

BACKGROUND The clinical presentation of acute Charcot arthropathy in the diabetic population usually follows the Eichenholtz classification. We present three usual cases of Charcot arthropathy presenting with rapid primary bone resorption in the absence of subluxation, dislocation and/or fracture. METHODS A review of the literature was performed. To our knowledge Charcot arthropathy has not been previously described as primary bone resorption. CASE REPORTS Three cases encountered at our specialist multidisciplinary High Risk Foot Clinic (HRFC) presented with primary bony resorption without features of subluxation, dislocation and/or fracture. DISCUSSION Aggressive primary bone resorption was initially thought due to infection; a diagnostic dilemma that delayed optimal treatment. Late bone resorption in typical Charcot is linked to unregulated proinflammatory cytokines (IL-1β, IL-6 and TNFα) that lead to increased osteoclastic activity. The pathophysiology of osteolysis in aggressive primary bony resorption may relate to a disturbance in the balance between RANK-L and OPG. CONCLUSION Primary resorption of bone without subluxation, dislocation and/or fracture can represent an active Charcot process. Prudent use of serial radiography and early MRI to look for the widespread bone and soft tissue oedema is recommended.

Relationship of Surgical Accuracy and Clinical Outcomes in Charitè Lumbar Disc Replacement

To retrospectively assess the clinical and functional outcomes of a group of patients receiving Charitè lumbar disc replacement and to compare those outcomes to the corresponding surgical technical accuracy.

Cement penetration after patella venting

There is a high rate of patellofemoral complications following total knee arthroplasty. Optimization of the cement-bone interface by venting and suction of the tibial plateau has been shown to improve cement penetration. Our study was designed to investigate if venting the patella prior to cementing improved cement penetration. Ten paired cadaver patellae were allocated prior to resurfacing to be vented or non-vented. Bone mineral density (BMD) was measured by DEXA scanning. In vented specimens, a 1.6 mm Kirschner wire was used to breach the anterior cortex at the center. Specimens were resurfaced with standard Profix instrumentation and Versabond bone cement (Smith and Nephew PLC, UK). Cement penetration was assessed from Faxitron and sectioned images by a digital image software package (ImageJ V1.38, NIH, USA). Wilcoxon rank sum test was used to assess the difference in cement penetration between groups. The relationship between BMD and cement penetration was analyzed by Pearson correlation coefficient. There was a strong negative correlation between peak BMD and cement penetration when analyzed independent of experimental grouping (r(2)=-0.812, p=0.004). Wilcoxon rank sum testing demonstrated no significant difference (rank sum statistic W=27, p=0.579) in cement penetration between vented (10.53%+/-4.66; mean+/-std dev) and non-vented patellae (11.51%+/-6.23; mean+/-std dev). Venting the patella using a Kirschner wire does not have a significant effect on the amount of cement penetration achieved in vitro using Profix instrumentation and Versabond cement.

Wound Discharge After Pharmacological Thromboprophylaxis in Lower Limb Arthroplasty

BACKGROUND The benefits vs risk of pharmacological prophylaxis for thromboembolic disease in orthopedic patients remain controversial. Pharmacological thromboprophylaxis regimes are commonly used in this patient group. Few studies specifically examine wound complications attributable to this therapy. In this prospective trial, we investigated the effect of various regimens on postoperative wounds. METHODS A prospective, observational, multicenter study involving patients undergoing elective hip or knee arthroplasty was undertaken. Patients were divided into 3 groups depending on thromboprophylaxis: no anticoagulation, aspirin, or low molecular weight heparin (LMWH) (enoxaparin). Surgical wounds were evaluated for each regime using the Southampton Wound Assessment Score. RESULTS Over a 12-month period, 327 patients were enrolled with a mean age of 68.1 years (±11.2 years). There were 105 patients in the no anticoagulation group (32.1%), 97 patients in the aspirin group (29.7%), and 125 patients in the LMWH group (38.2%). Wound scores were evaluated for evidence and amount of discharge. The use of LMWH conferred a 4.92 times greater risk and aspirin a 3.64 times greater risk of wound discharge than no pharmacological thromboprophylaxis (P < .0001). There were no significant differences in the incidence of deep vein thrombosis or pulmonary embolus between groups either as an inpatient or postdischarge. CONCLUSION There is a significant increase in the risk of wound discharge when aspirin or LMWH is used in arthroplasty patients. As potential complications of wound problems are significant, a more balanced view of risk vs benefit needs to be taken when prescribing thromboprophylaxis for this patient group.

Physiological Nocturnal Hand Swelling: A Prospective Evaluation of Healthy Volunteers

PURPOSE The goal of this study was to quantify the variation in daily volume that is expected in the normal hand. Our hypothesis is that hand swelling occurs overnight. METHODS Hand volume measurements of 36 healthy volunteers with no hand pathology were taken daily at 8 am, 2 pm, and 8 pm over a 3-day period. Participants were blinded to the objective of the study. Statistical analysis was performed to determine if any of the time points or patient demographics were associated with an increased change in hand volume. RESULTS Thirty-six healthy volunteers with mean age of 40.9 years and mean body mass index of 24.2 kg/m2 were enrolled. Twenty-one volunteers were men and 15 were women. Three of the volunteers were left-handed. The key finding from this study was that the change in hand volume overnight (8 pm-8 am) is significantly different than the change in hand volume from 8 am to 2 pm and from 2 pm to 8 pm. Although there was a significant reduction in hand volume from 8 am to 2 pm, the further reduction in hand volume from 2 pm to 8 pm was not significant after correcting for the number of post hoc comparisons. In addition, demographic variables such as age, body mass index, and sex did not influence changes in hand volume. CONCLUSIONS Physiological hand swelling occurs overnight in individuals without active or prior hand pathology. Hand volume then decreases over the course of the day in these same individuals. CLINICAL RELEVANCE By investigating the changes in hand volume that occur overnight and throughout the day, we gain a better understanding of the temporal relationship between hand swelling and symptoms of chronic hand disease.

A Prospective Evaluation of Adverse Reactions to Single-Dose Intravenous Antibiotic Prophylaxis During Outpatient Hand Surgery

Background: While it is established that routine prophylactic antibiotics are not needed for all hand surgery, some cases do require it. The purpose of this study was to determine the rate of adverse reactions resulting from prophylactic antibiotic administration on patients undergoing outpatient hand and upper extremity surgical procedures. We hypothesize that the rate of complications resulting from the use of antibiotic prophylaxis is smaller than that reported in the currently referenced literature. Methods: We prospectively evaluated 570 consecutive patients undergoing outpatient upper extremity surgery. Patients were excluded if they were on antibiotics prior to surgery, were discharged on antibiotics, or if they wished to be excluded. Nineteen patients were excluded, resulting in a study cohort of 551 patients. Patients were monitored perioperatively, 2 to 3 days postoperatively, during the first postoperative visit and 1 month postoperatively for adverse reactions. The type and timing of the adverse reaction was recorded. Results: Five hundred fifty-one patients were included for evaluation and 8 patients (1.5%) developed an adverse reaction to antibiotics. Five patients (0.9%) reported a rash and 3 patients (0.5%) reported diarrhea within 3 days of surgery. There were no anaphylactic reactions or complications necessitating hospital transfer or admission in the postoperative period. Conclusion: This study represents a prospective investigation designed to determine the rate of adverse reactions to single-dose antibiotics given during outpatient hand surgery. We conclude that the use of intravenous, single-dose prophylactic antibiotic is safe in the outpatient setting for cases that require it.