Osteoarthritis (OA) is a chronic degenerative joint disease with cartilage degeneration, subchondral bone sclerosis, synovial inflammation and osteophyte formation. Sensory nerves play an important role in bone metabolism and in the progression of inflammation. This study explored the effects of capsaicin-induced sensory nerve denervation on OA progression in mice. This study was approved by the Institutional Animal Care and Use Committee. OA was induced via destabilization of the medial meniscus (DMM). Sensory denervation was induced by subcutaneous injection of capsaicin (90mg/kg) one week prior to DMM. One week after capsaicin injection, sensory denervation in the tibia was confirmed by immunofluorescent staining with calcitonin gene-related peptide (CGRP)-specific antibodies. Four weeks after DMM, micro-CT scans, histological analysis and RT-PCR tests were performed to evaluate OA progression. Statistical analysis was performed using SPSS 13. P values of less than 0.05 were considered statistically significant. Subcutaneous injection of capsaicin successfully induced tibial sensory denervation (n=3), which aggravated OA by increasing subchondral bone resorption. The Osteoarthritis Research Society International (OARSI) score of the capsaicin+DMM group (n=8) (11.81±2.92) was significantly higher (P=0.003) than the score of the vehicle+DMM group (n=8) (8.31±1.80). The BV/TV of the tibial subchondral bone in the capsaicin+DMM group (n=8) was 55.67%±3.08, which was significantly lower (P < 0 .001) than in the vehicle+DMM group (n=8) (86.22%±1.92). In addition, the level of expression of somatostatin in the capsaicin+DMM group (n=8) was lower than in the vehicle+DMM group (n=8) (P=0.007). Capsaicin-induced sensory denervation increased tibial subchondral bone resorption, reduced the expression of somatostatin and eventually exacerbated the existing cartilage degeneration in mice. Despite capsaicin is often used clinically to relieve OA pain, its safety is still controversial according to the OARSI guidelines for the non-surgical management of knee osteoarthritis. The findings of our study suggest that application of capsaicin, although effective in relieving pain, may accelerate the progression of existing OA

Introduction. The management of chronic wrist pain is a challenging clinical problem. Wrist denervation aims to achieve an improvement in pain through selective neurotomy, irrespective of cause. Numerous authors have reported their experience and demonstrated a range of clinical outcomes. No studies to date have reliably identified patient populations in whom denervation surgery is most likely to succeed. We aimed to establish and investigate a new approach, combining local anaesthetic injections with a uniquely tailored functional assessment by a hand therapist, to act as a tool to identify individuals in whom surgical denervation is more likely to yield benefit. Methods. We conducted a retrospective review of 17 patients who had undergone wrist denervation procedures following our method of pre-operative assessment and selection. Patients in whom denervation was combined with other diagnostic or therapeutic surgical procedures were excluded. Each patient underwent an initial assessment by a hand therapist in which pain and functional scores were recorded using the Patient Rated Wrist Evaluation (PRWE). Further unique assessments of function were made, tailored to the functional goals and requirements of each patient. Pain scores were measured for each task. Local anaesthetic injections were then administered around the nerves considered for neurotomy and the assessments were repeated. Patients who demonstrated clear improvements in pain and function underwent surgery. Post-operative assessments of pain and function were repeated. Results. Results were analysed using the Wilcoxon signed ranks test. There was a statistically significant improvement in pain following wrist denervation surgery (p=0.06) as well as an improvement in function as measured on PRWE (p=0.01). Furthermore, the degree of improvement following local anesthetic injection correlated with the degree of improvement seen after surgery (p=0.06). Conclusions. Regardless of underlying diagnosis, improvements in pain and function following our assessment and selection process correlated with improvements seen after denervation surgery

While a tourniquet is traditionally used to obtain a dry field during primary TKA (and is also thought to reduce perioperative blood loss), adverse effects of tourniquet use have been reported. Avoiding routine use of the tourniquet during TKA can minimise certain complications while improving the quality of the early result. Most studies of TKA with and without tourniquet show little difference in all forms of blood loss except for intraoperative. Some studies even show less overall blood loss in groups without tourniquet use. Modern techniques to minimise intraoperative loss have included topical treatments, systemic medications, as well as a bipolar tissue sealer. Visualisation of bleeding vessels and their management intra-operatively can substantially reduce early post-op hemarthrosis. Tourniquet use has also been related to post-operative thigh pain. This is a negative aspect of tourniquet use that can interfere with physical therapy and rehabilitation. Occasionally it can be a significant factor in post-op recovery. Data supports the fact that avoiding a tourniquet or at least reducing pressure to the minimum necessary may help to reduce post-operative thigh pain. Ischemia and tissue damage can affect neuromuscular function and rehabilitation following TKA. The time necessary to achieve straight leg raising and knee flexion is delayed by tourniquet use during TKA. Compressive nerve injury also may result in secondary effects of denervation on distal tissues. This denervation can delay recovery of blood flow and increase vessel spasm, hemorrhage and edema. The degree of dysfunction is related to the magnitude of tourniquet compression. Tension in the lateral retinaculum is directly affected by tourniquet use. Observations from these studies would indicate that lateral release should be performed only if found necessary after tourniquet deflation in order to minimise the potential morbidity that accompanies this procedure. Although thromboembolic events can occur during TKA without, tourniquet use is associated with more frequent events when it is used. Finally, it is prudent to avoid the use of a tourniquet in patients with vascular calcifications around the knee or abdomen due to advanced arteriosclerosis, previous bypass grafts, or reduced limb or tissue blood supply for any reason. Routine TKA with minimal tourniquet use greatly simplifies its performance in those settings where it is contra-indicated

While a tourniquet is traditionally used to obtain a dry field during primary TKA (and is also thought to reduce peri-operative blood loss), adverse effects of tourniquet use have been reported. Avoiding routine use of the tourniquet during TKA can minimise certain complications while improving the quality of the early result. Most studies of TKA with and without tourniquet show little difference in all forms of blood loss except for intra-operative. Some studies even show less overall blood loss in groups without tourniquet use. Modern techniques to minimise intra-operative loss have included topical treatments, systemic medications, as well as a bipolar tissue sealer. Visualisation of bleeding vessels and their management intra-operatively can substantially reduce early post-op hemarthrosis. Tourniquet use has also been related to post-operative thigh pain. This is a negative aspect of tourniquet use that can interfere with physical therapy and rehabilitation. Occasionally it can be a significant factor in post-op recovery. Data supports the fact that avoiding a tourniquet or at least reducing pressure to the minimum necessary may help to reduce post-operative thigh pain. Ischemia and tissue damage can affect neuromuscular function and rehabilitation following TKA. The time necessary to achieve straight leg raising and knee flexion is delayed by tourniquet use during TKA. Compressive nerve injury also may result in secondary effects of denervation on distal tissues. This denervation can delay recovery of blood flow and increase vessel spasm, hemorrhage and edema. The degree of dysfunction is related to the magnitude of tourniquet compression. Tension in the lateral retinaculum is directly affected by tourniquet use. Observations from these studies would indicate that lateral release should be performed only if found necessary after tourniquet deflation in order to minimise the potential morbidity that accompanies this procedure. Although thrombo-embolic events can occur during TKA without, tourniquet use is associated with more frequent events when it is used. Finally, it is prudent to avoid the use of a tourniquet in patients with vascular calcifications around the knee or abdomen due to advanced arteriosclerosis, previous bypass grafts, or reduced limb or tissue blood supply for any reason. Routine TKA with minimal tourniquet use greatly simplifies its performance in those settings where it is contra-indicated

Most acetabular defects can be treated with a cementless acetabular cup and screw fixation. However, larger defects with segmental bone loss and discontinuity often require reconstruction with augments, a cup-cage, or triflange component – which is a custom-made implant that has iliac, ischial, and pubic flanges to fit the outer table of the pelvis. The iliac flange fits on the ilium extending above the acetabulum. The ischial and pubic flanges are smaller than the iliac flange and usually permit screw fixation into the ischium and pubis. The custom triflange is designed based on a pre-operative CT scan of the pelvis with metal artifact reduction, which is used to generate a three-dimensional image of the pelvis and triflange component. The design of the triflange involves both the manufacturing engineer and surgeon to determine the most appropriate overall implant shape, screw fixation pattern, and cup location and orientation. A plastic model of the pelvis, and triflange implant can be made in addition to the triflange component to be implanted, in order to assist the surgeon during planning and placement of the final implant in the operating room. A wide surgical exposure is needed including identification of the sciatic nerve. Proximal dissection of the abductors above the sciatic notch to position the iliac flange can risk denervation of the abductor mechanism. Blood loss during this procedure can be excessive. Implant survivorship of 88 to 100% at 53-month follow-up has been reported. However, in a series of 19 patients with Paprosky type 3 defects, only 65% were considered successful. The custom triflange also tends to lateralise the hip center which may adversely affect hip mechanics. The use of a triflange component is indicated in cases with massive bone loss or discontinuity in which other reconstructive options are not considered suitable

Supercharged end-to-side nerve transfer for severe cubital tunnel syndrome is a recently developed technique which involves augmenting the ulnar motor branch with anterior interosseous nerve (AIN). Previous studies suggested that this technique augments or “babysits” the motor end plates until reinnervation occurs, however, some authors suggested possible reinnervation by the donor nerve. We present two cases where this transfer was done for rapid progressive (6–9 months) cubital tunnel syndrome. The first case was a 57 year-old right hand dominant female who presented to us with severe right cubital tunnel syndrome clinically, including intrinsic wasting and claw deformity. The patient had significant loss of function and visible atrophy to her hand intrinsics over the last few months. Electrodiagnostic studies confirmed the diagnosis of severe cubital tunnel syndrome demonstrating axonal loss, positive sharp waves and fibrillations in the ulnar nerve distribution distally. The patient underwent cubital tunnel ulnar nerve release, subcutaneous anterior transposition, Guyon's canal release along with an AIN to ulnar motor nerve end-to-side transfer. Patient-based functional outcome instruments were prospectively collected with improved overall pain and function as demonstrated from a quickDASH score of 9.1 1 year post-op in comparison to a score of 34.1 pre-op. Recovery was monitored clinically and electrodiagnostic studies at 6 months and 1 year post-operatively. She demonstrated improved intrinsic muscle bulk and strength. The nerve studies at one year showed reinnervation with large amplitude motor unit potentials in the 1st dorsal interosseous and abductor digiti minimi but the 5th finger sensory response remained absent. The second case was a 58 year-old right hand dominant male diagnosed with severe and progressive right cubital tunnel syndrome. Clinically, he had significant muscle wasting and weakness and confirmed denervation on electrodiagnostic studies. He underwent the same surgical procedure as described for the first case and follow-up regimen. The patient demonstrated improved pain score and significant overall function recovery with a quickDASH score of 11.4 one year post-op in comparison to 72.7 pre-op. Nerve studies at one year confirmed our clinical impression, showing ulnar nerve reinnervation with large amplitude motor unit potentials in the 1st dorsal interosseous, while sensory response remained absent. It is yet unclear if end-to-side nerve transfers allow reinnervation of the target muscles. Previous studies have demonstrated clinical improvement with this transfer, however we are unaware of any electrodiagnostic studies demonstrating this effect. These two cases support the notion of reinnervation after an end-to-side procedure. Further studies are needed to assess outcomes of such nerve transfers

When dealing with the patella in total knee arthroplasty (TKA) there are three philosophies. Some advocate resurfacing in all cases, others do not resurface, and a third group selectively resurfaces the patella. The literature does not offer one clear and consistent message on the topic. Treatment of the patella and the ultimate result is multifactorial. Factors include the patient, surgical technique, and implant design. With respect to the patient, inflammatory versus non-inflammatory arthritis, pre-operative presence or absence of anterior knee pain, age, sex, height, weight, and BMI affect results of TKA. Surgical technique steps to enhance the patellofemoral articulation include: 1) Restore the mechanical axis to facilitate patellofemoral tracking. 2) Select the appropriate femoral component size with respect to the AP dimension of the femur. 3) When performing anterior chamfer resection, measure the amount of bone removed in the center of the resection and compare to the prosthesis. Do not overstuff the patellofemoral articulation by taking an inadequate amount of bone. 4) Rotationally align the femur appropriately using a combination of the AP axis, the transepicondylar axis, the posterior condylar axis, and the tibial shaft axis. 5) If faced with whether to medialise or lateralise the femoral component, always lateralise. This will enhance patellofemoral tracking. 6) When resurfacing the patella, only evert the patella after all other bony resections have been performed. Remove peripheral osteophytes and measure the thickness of the patella prior to resection. Make every effort to leave at least 15 mm of bone and never leave less than 13 mm. 7) Resect the patella. The presenter prefers a freehand technique using the insertions of the patellar tendon and quadriceps tendon as a guide, sawing from inferior to superior, then from medial to lateral to ensure a smooth, flat, symmetrical resection. Medialise the patellar component and measure the thickness of reconstruction. 8) When not resurfacing the patella, surgeons generally remove all the peripheral osteophytes, and some perform denervation using electrocautery around the perimeter. 9) Determine appropriate patellofemoral tracking only after the tourniquet is released. 10) Close the knee in flexion so as not to tether the soft tissues about the patella and the extensor. With or without patellar resurfacing, implant design plays in important role in minimizing patellofemoral complications. Newer designs feature a so-called “swept back” femur in which the chamfer resection is deepened, and patellofemoral overstuffing is minimised. Lateralizing the trochlear groove on the anterior flange, orienting it in valgus alignment, and gradually transitioning to midline have improved patellofemoral tracking. Extending the trochlear groove as far as possible into the tibiofemoral articulation has decreased patellofemoral crepitation and patellar clunk in posterior stabilised designs. With respect to the tibial component, providing patellar relief anteriorly in the tibial polyethylene has facilitated range of motion and reduced patellar impingement in deep flexion. On the patella side, the all-polyethylene patella remains the gold standard. While data exist to support all three viewpoints in the treatment of the patella in TKA, it is the presenter's opinion that the overwhelming data support patella resurfacing at the time of primary TKA. It is clear from the literature that the status of the patellofemoral articulation following TKA is multifactorial. Surgical technique and implant design are key to a well-functioning patellofemoral articulation. Pain is the primary reason patients seek to undergo TKA. Since our primary goal is to relieve pain, and there has been a higher incidence of anterior knee pain reported without patellar resurfacing, why not resurface the patella?

Injury to the sciatic nerve is one of the more serious complications of acetabular fracture and traumatic dislocation of the hip, both in the short and long term. We have reviewed prospectively patients, treated in our unit, for acetabular fractures who had concomitant injury to the sciatic nerve, with the aim of predicting the functional outcome after these injuries.

Of 136 patients who underwent stabilisation of acetabular fractures, there were 27 (19.9%) with neurological injury. At initial presentation, 13 patients had a complete foot-drop, ten had weakness of the foot and four had burning pain and altered sensation over the dorsum of the foot. Serial electromyography (EMG) studies were performed and the degree of functional recovery was monitored using the grading system of the Medical Research Council. In nine patients with a foot-drop, there was evidence of a proximal acetabular (sciatic) and a distal knee (neck of fibula) nerve lesion, the double-crush syndrome.

At the final follow-up, clinical examination and EMG studies showed full recovery in five of the ten patients with initial muscle weakness, and complete resolution in all four patients with sensory symptoms (burning pain and hyperaesthesia). There was improvement of functional capacity (motor and sensory) in two patients who presented initially with complete foot-drop. In the remaining 11 with foot-drop at presentation, including all nine with the double-crush lesion, there was no improvement in function at a mean follow-up of 4.3 years.

Tendinopathy is a debilitating musculoskeletal condition which can cause significant pain and lead to complete rupture of the tendon, which often requires surgical repair. Due in part to the large spectrum of tendon pathologies, these disorders continue to be a clinical challenge. Animal models are often used in this field of research as they offer an attractive framework to examine the cascade of processes that occur throughout both tendon pathology and repair. This review discusses the structural, mechanical, and biological changes that occur throughout tendon pathology in animal models, as well as strategies for the improvement of tendon healing.

Cite this article: Bone Joint Res 2014;3:193–202.