A simple formula to control posterior tibial slope during proximal tibial osteotomies.

BACKGROUND: High tibial osteotomy surgery is a widely successful joint-preserving procedure which alters the hip-knee-ankle axis which can delay the progression of osteoarthritis; however, conventional osteotomy surgical procedures do not adequately control the posterior tibial slope. This study aimed to determine the key variables influencing posterior tibial slope during high tibial osteotomy and provide a simple means of implementing the findings during pre-operative planning. METHODS: A virtual cohort of twenty-eight proximal tibia geometries of knee osteoarthritis patients was used in the study. Firstly, absolute posterior tibial slope values were contrasted using anatomical and posterior mechanical axis measurement approaches. Secondly, the influence of variables affecting posterior tibial slope change during osteotomy surgery was investigated using 3D preoperative planning surgical simulation and analytical modelling. FINDINGS: There was a poor correlation (R2 = 0.38) between the different clinical measurements of posterior tibial slope; with an average of 7.0 ± 1.3° and 14.8 ± 2.2° respectively. An analytical solution for the change in posterior tibial slope was derived based on the hinge axis angle and the osteotomy opening angle. For three different opening angles (6°, 9° and 12°) and seven different hinge axis orientations (-30° to +30°), the results obtained were identical for the analytical model and the 3D preoperative planning. INTERPRETATION: This study determined that the key variables affecting posterior tibial slope during high tibial osteotomy are the osteotomy opening angle and the hinge axis orientation. The derived formula provides a simple means of determining the change in posterior tibial slope resulting from a particular surgical approach.

Surgeon and physiotherapist approaches to operative or non-operative management of people with recurrent patellar dislocation: A case-based UK survey.

BACKGROUND: Physiotherapists are often key decision-makers on when to refer patients with recurrent patellar dislocation for surgical opinion. Limited guidance exists to aid this decision. Differences in orthopaedic surgeons' and physiotherapists' views on which patients and when to refer people for surgical consideration or non-operative care may affect outcome. This study aimed to explore orthopaedic surgeons and physiotherapists decision-making surrounding treatment opinions for patients with recurrent patellar dislocation. METHODS: An online survey performed. UK registered and practicing orthopaedic surgeons and physiotherapists were invited to participate. The survey utilised two vignettes and a series of related questions to ascertain respondents' views on decision-making to surgical referral for people with recurrent patellar dislocation. Data were analysed using descriptive statistics and inferential statistical tests to explore factors related to responses. RESULTS: Eighty four respondent surveys were analysed (38 surgeons, 46 physiotherapists). Overall, there was a low level of agreement amongst respondents for the management of the vignettes (k = 0.215, p = < 0.0005). Some disparity existed between the professions on the definition of recurrent patellar dislocations and the clinical features which may require an early surgical assessment. Physiotherapists were three times more likely to delay a surgical opinion for the vignettes presented in this study than the surgeons. CONCLUSION: This is the first study to investigate orthopaedic surgeons' and physiotherapists' views on decision-making around surgical or non-operative management for recurrent patellar dislocations. High-quality research is required to underpin explicit guidance on decision-making regarding management of recurrent patellar dislocation.

Robotic Assisted Patellofemoral Joint Replacement: Surgical Technique, Tips and Tricks.

In this article we wish to provide MAKO robotic knee users a surgical guide including tips and tricks on performing MAKO robotic-assisted patellofemoral joint replacements. The senior authors in this paper from the Exeter Knee Reconstruction Unit, United Kingdom are highly experienced MAKO users who have been performing MAKO assisted Patellofemoral joint replacements since 2017.

Robotic-Assisted Patellofemoral Replacement-Correlation of Preoperative Planning with Intraoperative Implant Position and Early Clinical Experience: A Minimum 2-Year Follow-up.

Patello-femoral arthroplasty (PFA) is successful in a selected group of patients and yields a good functional outcome. Robotic-assisted knee arthroplasty has been shown to provide better implant positioning and alignment. We aim to report our early outcomes and to compare Mako's (Robotic Arm Interactive Orthopaedic System [RIO]) preoperative implant planning position to our intraoperative PFA implant position. Data for this study was prospectively collected for 23 (two bilateral) patients who underwent robotic-assisted PFA between April 2017 and May 2018. All preoperative implant position planning and postoperative actual implant position were recorded. Presence of trochlear dysplasia and functional outcome scores were also collected. There were 17 (two bilateral) female and 6 male patients with a mean age of 66.5 (range: 41-89) years. The mean follow-up period was 30 (range: 24-37) months. Eighteen knees (72%) had evidence of trochlear dysplasia. The anterior trochlear line was on average, 7.71 (range: 3.3-11.3) degrees, internally rotated to the surgical transepicondylar axis and on average 2.9 (range: 0.2-6.5) degrees internally rotated to the posterior condylar line. The preoperative planning range was 4-degree internal to 4-degree external rotation, 4-degree varus to 6-degree valgus, and 7-degree flexion to 3-degree extension. The average difference between preoperative planning and intraoperative implant position was 0.43 degrees for rotation (r = 0.93), 0.99 degrees for varus/valgus (r = 0.29), 1.26 degrees for flexion/extension (r = 0.83), and 0.34 mm for proudness (r = 0.80). Six patients (24%) had a different size component from their preoperative plan (r = 0.98). The mean preoperative Oxford Knee Score (OKS) was 16 and the mean postoperative OKS was 42. No patient had implant-related revision surgery or any radiological evidence of implant loosening at final follow-up. Our early results of robotic PFA are promising. Preoperative Mako planning correlates closely with intraoperative implant positioning. Longer follow-up is needed to assess long-term patient outcomes and implant survivorship.

Personalised high tibial osteotomy has mechanical safety equivalent to generic device in a case-control in silico clinical trial.

Background: Despite favourable outcomes relatively few surgeons offer high tibial osteotomy (HTO) as a treatment option for early knee osteoarthritis, mainly due to the difficulty of achieving planned correction and reported soft tissue irritation around the plate used to stablise the osteotomy. To compare the mechanical safety of a new personalised 3D printed high tibial osteotomy (HTO) device, created to overcome these issues, with an existing generic device, a case-control in silico virtual clinical trial was conducted. Methods: Twenty-eight knee osteoarthritis patients underwent computed tomography (CT) scanning to create a virtual cohort; the cohort was duplicated to form two arms, Generic and Personalised, on which virtual HTO was performed. Finite element analysis was performed to calculate the stresses in the plates arising from simulated physiological activities at three healing stages. The odds ratio indicative of the relative risk of fatigue failure of the HTO plates between the personalised and generic arms was obtained from a multi-level logistic model. Results: Here we show, at 12 weeks post-surgery, the odds ratio indicative of the relative risk of fatigue failure was 0.14 (95%CI 0.01 to 2.73, p = 0.20). Conclusions: This novel (to the best of our knowledge) in silico trial, comparing the mechanical safety of a new personalised 3D printed high tibial osteotomy device with an existing generic device, shows that there is no increased risk of failure for the new personalised design compared to the existing generic commonly used device. Personalised high tibial osteotomy can overcome the main technical barriers for this type of surgery, our findings support the case for using this technology for treating early knee osteoarthritis.

Personalised high tibial osteotomy has mechanical safety equivalent to generic device in a case-control in silico clinical trial.

BACKGROUND: Despite favourable outcomes relatively few surgeons offer high tibial osteotomy (HTO) as a treatment option for early knee osteoarthritis, mainly due to the difficulty of achieving planned correction and reported soft tissue irritation around the plate used to stablise the osteotomy. To compare the mechanical safety of a new personalised 3D printed high tibial osteotomy (HTO) device, created to overcome these issues, with an existing generic device, a case-control in silico virtual clinical trial was conducted. METHODS: Twenty-eight knee osteoarthritis patients underwent computed tomography (CT) scanning to create a virtual cohort; the cohort was duplicated to form two arms, Generic and Personalised, on which virtual HTO was performed. Finite element analysis was performed to calculate the stresses in the plates arising from simulated physiological activities at three healing stages. The odds ratio indicative of the relative risk of fatigue failure of the HTO plates between the personalised and generic arms was obtained from a multi-level logistic model. RESULTS: Here we show, at 12 weeks post-surgery, the odds ratio indicative of the relative risk of fatigue failure was 0.14 (95%CI 0.01 to 2.73, p = 0.20). CONCLUSIONS: This novel (to the best of our knowledge) in silico trial, comparing the mechanical safety of a new personalised 3D printed high tibial osteotomy device with an existing generic device, shows that there is no increased risk of failure for the new personalised design compared to the existing generic commonly used device. Personalised high tibial osteotomy can overcome the main technical barriers for this type of surgery, our findings support the case for using this technology for treating early knee osteoarthritis.

Surgical treatment to realign the knee, called a high tibial osteotomy, is effective at relieving symptoms of knee osteoarthritis but the operation is difficult. A new personalised treatment with simpler surgery has been designed. The aim of this study was to investigate the safety of the new personalised treatment compared to the standard treatment. For the first time, a detailed computer simulation clinical trial was performed, using imaging data from 28 real patients. The computer simulation compared the risk of the implant failure between the personalised and standard treatments. The personalised treatment did not have a higher risk of implant failure than standard treatment. This supports further clinical studies looking at the benefits of personalised over standard realignment surgery. The personalised treatment has the potential to allow much more widespread use of realignment surgery to treat early knee osteoarthritis.

Remnant preservation does not affect accuracy of tibial tunnel positioning in single-bundle ACL reconstruction.

PURPOSE: Remnant preservation, in anterior cruciate ligament (ACL) reconstruction, has potential biological advantages. However, graft positioning remains vital to functional outcome and the prevention of failure. The aim of this study was to investigate the accuracy and precision of tibial tunnel positioning in remnant preservation single-bundle hamstring reconstruction. METHODS: Fifty consecutive adult patients, with isolated ACL rupture, were recruited to a prospective study. Remnant preservation was performed in all cases where > 25% of the native ACL was present. Three-dimensional computer tomography was preformed 3-6 months post-operatively to assess tibial tunnel position (using a grid-based measurement). Accuracy and precision of this technique were assessed against published anatomical data in direct comparison with the group where remnant preservation could not be performed. RESULTS: Two patients withdrew following surgery. In the remaining groups (31 remnant preservation; 17 non-remnant preservation), no difference was demonstrated in tunnel position (40.4 ± 6.7% (anterior-to-posterior) and 47.4 ± 1.5% (medial-to-lateral) vs. 38.8 ± 4.9% and 46.7 ± 1.5%, respectively; n.s.), accuracy (6.1% vs. 4.8%; n.s.) or precision (3.9% vs. 2.8%; n.s.). CONCLUSIONS: Remnant preservation can be safely performed without compromising tunnel position. Therefore, the potential benefits of this technique can be utilised, in clinical practice, without sacrificing the ability to optimize tibial tunnel positioning. LEVEL OF EVIDENCE: III.

A comparison of femoral tunnel placement in ACL reconstruction using a 70° arthroscope through the anterolateral portal versus a 30° arthroscope through the anteromedial portal: a pilot 3D-CT study.

BACKGROUND: Graft malposition is a risk factor for failure of anterior cruciate ligament reconstruction. A 70° arthroscope improves visualisation of the medial wall of the lateral femoral condyle without switching portals. We investigated whether the use of this arthroscope affected the accuracy and precision of femoral tunnel placement. METHODS: Fifty consecutive adult patients were recruited. Following one withdrawal and two exclusions, 47 patients (30 in group 1 (70° arthroscope), 17 in group 2 (30° arthroscope)) underwent three-dimensional computed tomography imaging using a grid-based system to measure tunnel position. RESULTS: No difference was found in the accuracy or precision of tunnels (mean position: group 1 = 33.3 ± 6.0% deep-shallow, 27.2 ± 5.2% high-low; group 2 = 31.7 ± 6.9% deep-shallow, 29.0 ± 6.2% high-low; not significant). A post-hoc power analysis suggests a study of 106 patients would be required. CONCLUSIONS: This pilot study suggests that tunnel position is not affected by the arthroscope used. An appropriately powered study could investigate this finding alongside other potential benefits of using a 70° arthroscope for this procedure. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02816606. Registered on 28 June 2016.

Flexible reamers create comparable anterior cruciate ligament reconstruction femoral tunnels without the hyperflexion required with rigid reamers: 3D-CT analysis of tunnel morphology in a randomised clinical trial.

PURPOSE: The hyperflexion required for femoral tunnel drilling in anterior cruciate ligament reconstruction can be challenging in patients with increased body habitus or musculature. Whilst allowing femoral tunnel creation without hyperflexion, additional benefits of flexible reamers have been proposed in terms of tunnel dimensions. The purpose of this study was to examine whether these theoretical benefits are seen in a clinical study. METHODS: Fifty adult patients (with isolated anterior cruciate ligament rupture) were randomised to reconstruction with either flexible or rigid femoral reamers. Femoral tunnel drilling was performed at 100° flexion (flexible system) or maximal hyperflexion (rigid system). Otherwise, the procedure was standardised. Femoral tunnel measurements were performed by a consultant musculoskeletal radiologist who was blinded to the method of femoral drilling. Tunnel position, length and angles (axial and coronal) were measured alongside aperture shape and exit point using three-dimensional computed tomography 3-6 months post-operatively. RESULTS: With no difference in tunnel position, tunnel length was found to increase with the use of the flexible system (37.8 ± 3.7 vs 35.0 ± 4.4 mm; p = 0.024). In addition, the exit point and fixation device were more anterior on the lateral femur using the flexible reamers (p = 0.016). No difference was seen in either tunnel angles or aperture shape. One case of incomplete posterior blow-out was seen in each of the study groups. CONCLUSIONS: This comparative study shows that flexible reamers can reproduce a desired femoral tunnel position with only small improvements of no clinical relevance. As this can be achieved without hyperflexing the knee, these systems can be used for all patients (even when hyperflexion is a challenge). LEVEL OF EVIDENCE: I.

Plain radiographs can be used for routine assessment of ACL reconstruction tunnel position with three-dimensional imaging reserved for research and revision surgery.

PURPOSE: The position of the osseous tunnels and graft during anterior cruciate ligament (ACL) reconstruction has been the subject of multiple studies aiming for either anatomical placement or an alternative. The assessment of these positions, using post-operative imaging, is therefore of interest to the surgeon in both the evaluation of surgical performance and surveillance of potential complications. The purpose of this review is to identify the optimal use of imaging in both the surveillance of clinical practice and in planning revision surgery. METHODS: A comprehensive systematic review was performed using Medline and Pubmed searches to identify radiological methods used to assess ACL reconstruction tunnel position. Commonly used methods were identified with correlation to either native anatomy or clinical results. RESULTS: The findings suggest that plain radiographs can be used to assess tunnel position and identify grafts that are positioned non-anatomically and may be at increased risk of complications. Computer tomography (CT) offers additional information about the tunnel aperture shape and size that is of importance for revision surgery and research projects whilst magnetic resonance imaging (MRI) provides further assessment of both graft integrity and associated soft tissue damage. CONCLUSION: In the surveillance of routine clinical practice, plain radiographs are sufficient to define tunnel position. The additional information provided by three-dimensional imaging is only required in revision surgery or research studies. LEVEL OF EVIDENCE: IV.

Anterior Cruciate Ligament Mechanoreceptors and their Potential Importance in Remnant-Preserving Reconstruction: A Review of Basic Science and Clinical Findings.

Mechanoreceptors, within the anterior cruciate ligament (ACL), are believed to have importance in proprioception, contributing to dynamic knee stability. The potential for reinnervation of the ACL graft is one of the proposed advantages of remnant-preserving reconstruction. The aim of this review is to summarize advances in the basic science underpinning this function, alongside recent clinical studies, to define the current role for remnant-preservation.A comprehensive systematic review was performed using PubMed and Medline searches. Studies were analyzed with particular focus placed on the methodology used to either identify mechanoreceptors or test proprioception.Contemporary work, using immunohistological staining, has shown mechanoreceptors primarily within proximity to the bony attachments of the ACL (peripherally in the subsynovial layer). The number of these receptors has been shown to decrease rapidly, following rupture, with adhesion to the posterior cruciate ligament slowing this decline. Recent studies have shown proprioceptive deficits, in both the injured and contralateral knees, with the clinical relevance of findings limited by testing methodology and the small differences found. The advantages of remnant-preservation, seen primarily in animal studies, have not been shown in systematic reviews or meta-analysis of clinical studies.The potential for reinnervation of the graft is likely time-dependent and reliant on continued loading of the remnant. Therefore, current clinical use and future research should focus on preserving remnants within 6 months of injury that remain loaded by adherence to the posterior cruciate ligament. Subsequent testing should account for central neurological changes and focus on clinically relevant outcomes.

The magnetic resonance imaging appearance of the anterolateral ligament of the knee in association with anterior cruciate rupture.

OBJECTIVE: The magnetic resonance imaging (MRI) appearance of the anterolateral ligament (ALL) has been described. However, the appearance of this structure and injury, in the presence of anterior cruciate ligament (ACL) injury, is less well defined. We studied the incidence of injury to the ALL and the pattern of this injury on MRI. MATERIALS AND METHODS: Following Institutional Review Board approval, a retrospective study of 375 consecutive MRI studies was performed. Cases were identified from a prospective database of ACL reconstruction patients. Following exclusions, 280 MRIs (277 patients; 197 males: 80 females; mean age 30.2 years, range, 16-54) were evaluated. Injury was defined as full thickness, partial thickness, or an avulsion fracture. Each study was independently assessed by two consultant musculoskeletal radiologists. RESULTS: Injury to the ALL was identified (by at least one observer) in only 10.7% of cases (2.50% full thickness, 7.50% partial thickness, and 0.71% avulsion fracture). There was an almost perfect level of interobserver agreement for both the identification of an injury (κ = 0.854) and grading of injury (κ = 0.858). The MRI incidence of ALL injury was significantly greater within 6 weeks of the knee injury (18.5 vs. 8.37%; p < 0.05). CONCLUSIONS: ALL injury was identified in only one-tenth of cases of ACL rupture. MRI changes can be reliably identified with strong agreement between observers. ALL injury is found more frequently on MRI within 6 weeks of the knee injury (compared to scans performed after this time period) suggesting that some injuries may resolve or become less visible.

Anatomic Anterior Cruciate Ligament Reconstruction: The Use of the Anterior Horn of the Lateral Meniscus as a Guide to Tibial Tunnel Placement.

Anatomic anterior cruciate ligament reconstruction has been shown to reduce the risk of graft failure and to improve patient-related clinical outcomes. The posterior border of the anterior horn of the lateral meniscus is a useful marker for anatomic tibial tunnel placement. Assessment of a preoperative magnetic resonance imaging scan can allow surgical planning of tibial tunnel placement to allow for anatomic, patient-specific tibial tunnel placement during anatomic anterior cruciate ligament reconstruction. We present this technique to show how to use the posterior border of the anterior horn of the lateral meniscus clinically.

The anterolateral ligament of the knee: unwrapping the enigma. Anatomical study and comparison to previous reports.

BACKGROUND: It has been suggested that the anterolateral ligament (ALL) of the knee may have importance in limiting rotational instability, and reconstruction may prevent a continued pivot-shift following anterior cruciate ligament surgery. However, the anatomy of this ligament has not been consistently reported in recent publications. We describe our experience of cadaveric dissection with reference to other published work. MATERIALS AND METHODS: Eleven fresh-frozen cadaveric knees were dissected using a standard technique. The ALL tissue was identified with internal rotation of the tibia and varus stress. Measurements were made using a digital caliper and details of the origin and insertion were recorded. RESULTS: The ALL was identified in ten of the 11 cadavers. The only specimen in which it was not identified was found to also have an anterior cruciate ligament deficiency. The mean dimensions were: length 40.1 (± 5.53) mm, width 4.63 (± 1.39) mm, thickness 0.87 (± 0.18) mm. The femoral origin was posterior and proximal to the lateral collateral ligament attachment in six knees, anterior and distal in three knees, and at the same site in one knee. The tibial insertion was a mean 17.7 (± 2.95) mm from Gerdy's tubercle (GT) and 12.3 (± 3.55) mm from the fibula head (FH). This was 59.5 (± 5.44) % from GT to FH. CONCLUSIONS: This anatomical data adds to previous information about the ALL. Our results support the finding that the ALL is a capsular thickening with meniscal attachment. The findings will help to guide the further work required to define the indications for reconstruction and appropriate grafts.

Revisiting the Anterolateral Ligament of the Knee.

Recent research has suggested that the anterolateral ligament (ALL) of the knee may have an important role in preventing persistent rotatory instability following anterior cruciate ligament (ACL) reconstruction.For this review, we performed a thorough literature search and identified the significant steps in the improvement of our understanding. This has progressed from historical reports to accurate characterization of the attachments and dimensions of the ALL through anatomical and histological studies. Alongside this, biomechanical data have demonstrated the role of this structure throughout the range of movement of the knee. Furthermore, the appearance of the ALL on magnetic resonance imaging has been comprehensibly described and radiological markers have been defined as a basis for suggested reconstructive procedures using fluoroscopy.We present a comprehensive review of the evolution of our understanding about this structure. Key advances in our understanding of the dimensions and attachments will guide research into reconstructive options. Further work is needed to determine the biomechanical and clinical outcome of extra-articular reconstruction of the ALL alongside ACL reconstruction.

Tibial tubercle osteotomy for patello-femoral joint disorders.

Tibial tubercle osteotomy has a long history in the management of patella instability and patello-femoral arthritis. This review aims to provide a comprehensive review of the literature describing the biomechanics of the patello-femoral joint and the rationale behind the use of the tibial tubercle osteotomy in modern day practice. Several different tibial tubercle osteotomies are available and we aim to detail the concepts behind their use and the subsequent clinical results. With continued developments of chondrocyte implantation techniques, the potential to fill defects on the chondral surface of either the patella or trochlea in conjunction with a tibial tubercle osteotomy may well become more commonplace in a group that is commonly young and difficult to manage. Level of evidence III.

Characterization of the anatomy of the anterolateral ligament of the knee using magnetic resonance imaging.

OBJECTIVE: The anterolateral ligament (ALL) may limit tibial internal rotation and pivot-shift following anterior cruciate ligament reconstruction. Previous studies, using magnetic resonance imaging (MRI) to identify this structure, have been inconsistent. We aimed to further characterize the anatomy of this ligament with reference to previous work. MATERIALS AND METHODS: Institutional Review Board approval was gained and a retrospective study of 154 consecutive 1.5-T MRI studies was performed by a consultant musculoskeletal radiologist. Cases with a lateral compartment or cruciate injury and patients under 16 years were excluded. A total of 100 MRIs (98 patients; 63 males: 35 females; mean age, 45.3 years, range, 16-85 years) were included in the study. RESULTS: The ALL was visualized partially in 94 (94.0%) of the cases and fully with distinct femoral and tibial fibers in 57 (57.0%) of the cases. Although the femoral origin was discreet in only 57 (57.0%) of cases, the tibial insertion (7.64 ± 1.26 mm below the joint-line) and meniscal attachment were demonstrated in all cases where the ligament was seen. Where the femoral origin was not seen, a broad expansion of the ligament was noted. We identified four types of meniscal attachment (complete, central, bipolar, and inferior-only). The thickness of the ALL, at the level of the joint-line, was 1.75 ± 0.57 mm. CONCLUSIONS: The ALL is a consistent structure with meniscal and tibial portions identifiable in the majority of MRI studies of the uninjured knee. There is an attachment to the lateral meniscus with anatomical variation described by our subclassification.

Bipolar radiofrequency plasma ablation induces proliferation and alters cytokine expression in human articular cartilage chondrocytes.

PURPOSE: The aim of the study was to determine the in vitro effects of plasma-mediated bipolar radiofrequency ablation on human chondrocyte compensatory proliferation and inflammatory mediator expression. METHODS: Human articular cartilage biopsy specimens, from total knee replacement, and human chondrocytes in alginate culture, from patients undergoing autologous chondrocyte implantation, were exposed to plasma ablation with a Paragon T2 probe (ArthroCare, Austin, TX). Instantaneous chondrocyte death was investigated with live/dead assays of biopsy specimens and cell cultures. Chondrocyte proliferation was determined by Hoechst staining of DNA on days 3 and 6. Messenger RNA expression of IL-1ß, IL-6, IL-8, tumor necrosis factor α, high-mobility group protein B1, matrix metalloproteinase 13, type IIA collagen, and versican was determined on days 3 and 6. RESULTS: Live/dead imaging showed a well-defined local margin of cell death ranging from 150 to 200 µm deep, both in the alginate gel and in the biopsy specimens exposed to plasma ablation. The ablation-exposed group showed a significant proliferation increase compared with control on day 3 (P < .043). There were significant increases compared with control in IL-6 expression on day 3 (P < .020) and day 6 (P < .045) and in IL-8 expression on day 3 (P < .048). No differences were seen for IL-1ß, tumor necrosis factor α, high-mobility group protein B1, matrix metalloproteinase 13, type II collagen, or versican. CONCLUSIONS: This study has shown that exposure to plasma-mediated ablation induces a well-defined area of immediate cell death and a short-term increase in proliferation with human articular chondrocytes in vitro. The exposure also alters cytokine expression for the same period, causing upregulation of IL-6 and IL-8. CLINICAL RELEVANCE: The results show the potential of plasma-mediated ablation to cause the onset of a tissue regeneration response with human articular cartilage.

The use of radiofrequency energy for arthroscopic chondroplasty in the knee.

We present a review of the current literature surrounding the use of radiofrequency energy for arthroscopic chondroplasty in the knee. This review article summarizes basic science, clinical efficacy, and recent advances in the understanding of radiofrequency energy use for the treatment of chondral lesions. Laboratory evidence of increased mechanical stability and decreased release of inflammatory mediators associated with the use of radiofrequency energy chondroplasty is described with clinical evidence of decreased pain and increased functional scores when compared with mechanical chondroplasty. We re-examine concerns about the immediate side effects of radiofrequency energy use, including damage to local structures, in light of new potentially contradictory results, as well as the progression of techniques and probe design. However, although reported complications are few, because the quality of clinical evidence about safety and efficacy remains low, we suggest cautious and judicious use of this technology until future research has clearly defined the long-term clinical outcomes and risks.

Septic arthritis of the elbow after chickenpox.

Musculoskeletal complications following chickenpox are rare among immunologically normal children. Septic arthritis after varicella is caused by group A Streptococcus and affects the knee most frequently. We present a case of septic arthritis of the elbow caused by Staphylococcus aureus. We review the English language literature on septic arthritis complicating chickenpox. We conclude that diagnosis and treatment should be carried out according to guidelines on de novo septic arthritis including the early use of magnetic resonance imaging.