Introduction. The incidence of dislocation after total hip arthroplasty (THA) was reported to be 0.5 to 10% in primary THA and 10 to 25 % in revision THA. The main causes of instability after THA were reported to be implant malalignment and inappropriate soft tissue tension. However, there was no study about quantitative data of soft tissue tension of unstable THA. The purpose of this study is to clarify the features of soft tissue tension of unstable THA in comparison to stable THA. Methods. The subjects were 15 patients with 15 THAs who had developed recurrent dislocation after primary THA. Thirty four patients with 37 THAs who developed no dislocation for one year after surgery were recruited as a stable THA group. In both group, all THAs were performed through posterolateral approach. In order to assess the soft tissue tension of THA, we recorded antero-posterior radiographs of the hips while applying distal traction to the leg with traction forces of 20?, 30%, 40% of body weight (BW). The distance of separation of the head and the cup after traction was measured under correction of magnification. Nine of 15 THAs in the unstable THA group and 32 of 37 THAs in the stable THA group were unilateral involvement. In the hips with unilateral involvement, the femoral offset difference between the healthy hip and the reconstructed hip were evaluated. Statistical analysis was performed with χ2 testand Mann-Whitney U test, and statistical significance was set at P<0.05. Results and Discussion. The average separation distance of the head and the cup was 5.2 ± 3.4mm (SD) at 40%BW, 4.3±3.2mm at 30%BW, and 3.2±2.8mm at 20%BW in the unstable THA group. The average separation distance of the head and the cup was 1.4±1.5mm at 40%BW, 1.1±1.4mm at 30%BW, and 0.9±1.2mm at 20%BW in the stable THA group. There were statistically significant differences in the separation distance between the groups in all ranges of traction force. The femoral offset difference between the operated side and the healthy side was −1.2±5.6mm in the unstable THA group and 3.1±4.8mm in the stable THA group. There were no significant difference in the femoral offset difference, however the femoral offset tends to be small in the unstable THA group compared to the stable THA group (P=0.05). The leg length discrepancy was −3.1±11.6mm in the unstable THA group and 2.7±7.1mm in the stable THA group. There were no significant difference in the leg length discrepancy (P=0.12). Conclusion. The separation distance of the head and the cup during leg distal traction in the unstable THA group is about four times larger than that in the stable THA group. The femoral offset tended to be smaller in the unstable THA group compared to the stable THA group

Fifteen-year survivorship studies demonstrate that total knee replacement have excellent survivorship, with reports of 85 to 97%. However, excellent survivorship does not equate to excellent patient reported outcomes. Noble et al. reported that 14% of their patients were dissatisfied with their outcome with more than half expressing problems with routine activities of daily living. There is also a difference in the patient's subjective assessment of outcome and the surgeon's objective assessment. Dickstein et al. reported that a third of total knee patients were dissatisfied, even though the surgeons felt that their results were excellent. Most of the patients who report lower outcome scores due so because their expectations are not being fulfilled by the total knee replacement surgery. Perhaps this dissatisfaction is a result of subtle soft tissue imbalance that we have difficulty in assessing intraoperatively and postoperatively. Soft tissue balancing techniques still rely on subjective feel for appropriate ligamentous tension by the surgeon. Surgical experience and case volume play a major role in each surgeon's relative skill in balancing the knee properly. New technology of “smart trials” with embedded microelectronics and accelerometers, used in the knee with the medial retinaculum closed, can provide dynamic, intra-operative feedback regarding knee quantitative compartment pressures and component tracking. After all bone cuts are made using the surgeon's preferred techniques, trial components with the sensored tibial trial are inserted and the knee is taken through a passive range of motion. After visualizing the resultant compartment pressures and tracking data on a graphical interface, the surgeon can decide whether to perform a soft tissue balance or a minor bone recuts. If soft tissue balancing is chosen, pressure data can indicate where to perform the release and allow the surgeon to assess the pressure changes as titrated soft tissue releases are performed. A multi-center study using smart trials has demonstrated dramatically better outcomes out to three years

The anatomy of the prevertebral region of the neck is of vital importance to orthopaedic surgeons when managing cervical spine trauma. Lateral radiographs are used in the acute assessment of this area as they are readily available and cost effectiveness. Thickening of the retropharyngeal space on a radiograph may be highly suggestive of serious and life-threatening pathologies. Accurate interpretation of radiological evidence is essential to assist the clinician in diagnosis. Current guidelines for radiological measurement state that these prevertebral soft tissues should not exceed 5mm at the midvertebral level of C3 and 20mm at C7. A ratio between soft tissue measurements and the width of the corresponding vertebra has also been championed as this takes into account magnification errors and variation in patient body habitus. Soft tissue measurements greater than 30% of the upper cervical vertebral bodies and greater than 100% of the lower cervical vertebral bodies are considered to be abnormal. The aim of this study was to assess reliability of current radiological guidelines on soft tissue measurement. A review of 200 consecutive normal lateral soft tissue cervical spine radiographs was undertaken. Patients were included if they were immobilised for blunt trauma and were aged 18 or older. Each patient included had cervical pathology excluded by a combination of clinical examination, flexion-extension views, CT and or MRI. Exclusion criteria included those patients with pre-existing cervical or retropharyngeal pathology, those who had been intubated or had a nasogastric tube passed. Two reviewers independently assessed soft tissue and bony widths at C3 and C7 using the PACs Software. All measurements were taken at the mid vertebral level, not at the end plates to ensure any anterior osteophytes did not create a falsely wide measurement. Plane film radiographs of 107 males and 93 females were included with an average age of 53. At the C3 level, mean soft tissue widths were 4.7mm ± 0.84mm SD and ranged from 2.7 to 7.4mm. The mean soft tissue width at C7 was 14.4mm ± 2.8mm SD with a range of 7.1 to 21.0 mm. Our results show 21.5% (43/200) of the patients exceeded the 5mm upper limit and 20% (40/200) exceeded the soft tissue to vertebra ratio at C3. Only 1% (2/200) of patients exceeded the upper limit of 20mm at C7 and only 2% (4/200) exceeded the soft tissue to vertebra ratio. The C3 guideline for maximum soft tissue widths has a poor specificity (78.5%) and the soft tissue to vertebral ratio at this level may also lead to further unnecessary investigation, as it too has a specificity of only 80%. However, the guidelines for PVST measurements at C7 are much more reliable with a specificity of 99.5% for the absolute measurement and 99% for the soft tissue to vertebra ratio. The ratio measurement has not conferred any significant diagnostic benefit over the static measurement. Current guidelines overestimate injuries at the C3 level but seem appropriate at the C7 level. There is no major benefit to using a ratio measurement over an absolute value

Most orthopaedic surgeons believe that total knee replacement has superb patient outcomes. Long-term results are excellent, with one study showing 15 year survivorship of 97%. However, our objective assessments of our patients' results are greater than patients' subjective assessments. In a study by Dickstein of total knee patients, one-third were not satisfied even though they were all thought to have had successful results by their orthopaedic surgeons. Noble and Conditt's study showed 14% of patients dissatisfied with their outcome with more than half expressing problems with routine activities of daily living. We are puzzled by this patient dissatisfaction since radiographs usually show normal component alignment and positioning. Perhaps some of these patients have subtle soft tissue imbalance and kinematic maltracking. Excellent aligned bone cuts can be expected with modern instrumentation, especially if patient specific cutting instruments or computer navigation are used. However, inadequate instrumentation exists for soft tissue balancing. It is usually based on feel and visual estimation. Soft tissue balancing techniques are difficult to teach and perform by a less experienced surgeon. Smart trials with load bearing and alignment sensors, which can be used with the medial retinaculum closed, will demonstrate the total knee kinematics and quantify soft tissue balance. Graduated soft tissue balancing can be performed while visualising changes in compartment loads. Studies are ongoing with smart trials to establish evidence-based clinical algorithms for soft tissue balancing and document the effects of these techniques on patient satisfaction and long-term outcome

In a study by Dickstein, one-third of total knee patients were not satisfied even though they were all thought to have had successful results by their orthopaedic surgeons. Noble and Conditt's study showed 14% of patients dissatisfied with their outcome with more than half expressing problems with routine activities of daily living. This occurs despite improvements in instrumentation to obtain proper alignment and implants with excellent kinematics and wear characteristics. Perhaps this dissatisfaction is a result of subtle soft tissue imbalance. Soft tissue imbalance can result in almost a third of early TKR revisions. Soft tissue balancing techniques still rely on subjective feel for appropriate ligamentous tension by the surgeon. Surgical experience and case volume play a major role in each surgeon's relative skill in balancing the knee properly. New technology of “smart trials” with embedded microelectronics, used in the knee with the medial retinaculum closed, can provide dynamic, intraoperative feedback regarding quantitative compartment pressures and component tracking. While visualising a graphical interface, the surgeon can assess the effect of sequential soft tissue releases performed to balance the knee. These smart trials also have imbedded accelerometers used to confirm that one is balancing a properly aligned knee and to provide the option of doing small bony corrections rather than soft tissue releases to obtain balance. A multi-center study using smart trials is demonstrating dramatically better outcomes at six months

Objective. Although both accurate component placement and adequate soft tissue balance have been recognized as essential surgical principle in total knee arthroplasty (TKA), the influence of intra-operative soft tissue balance on the post-operative clinical results has not been well investigated. In the present study, newly developed TKA tensor was used to evaluate soft tissue balance quantitatively. We analyzed the influence of soft tissue balance on the post-operative knee extension after posterior-stabilized (PS) TKA. Materials and Methods. Fifty varus type osteoarthritic knees implanted with PS-TKAs were subjected to this study. All TKAs were performed using measured resection technique with anterior reference method. The thickness of resected bone fragments was measured. Following each bony resection and soft tissue releases, we measured soft tissue balance at extension and flexion of the knee using a newly developed offset type tensor. This tensor device enabled quantitative soft tissue balance measurement with femoral trial component in place and patello-femoral (PF) joint repaired (component gap evaluation) in addition to the conventional measurement between osteotomized surfaces (osteotomy gap evaluation). Soft tissue balance was evaluated by the center gap (mm) and ligament balance (°; positive in varus) applying joint distraction forces at 40 lbs (178 N). Active knee extension in spine position was measured by lateral X-ray at 4 weeks post-operatively. The effect of each parameter (soft tissue balance evaluations, thickness of polyethylene insert and resected bone) on the post-operative knee extension was evaluated using simple linear regression analysis. P<0.05 was considered statistically significant. Results. The thickness of resected bone, flexion center gap and ligament balance at extension and flexion had no correlations to the knee extension angle. Thickness of polyethylene insert correlated positively to knee extension (r=0.38, p=0.007). Significant positive correlation were found between extension center gap in both osteotomy and component gap evaluation to the post-operative knee extension. The coefficient of correlations were 0.33 (p=.02) with osteotomy gap and 0.47 (p=0.0007) with component gap evaluation. Discussion and Conclusion. In the present study, extension center gap was found to positively correlate to the early post-operative knee extension. The extension center gap could be considered as the summation of the simultaneous gap from bone resections and the elongation of soft tissue envelope under joint distraction force applied by tensor. The soft tissue with the lower stiffness would be elongated more, and result in the larger center gap. Accordingly, the stiffness of the soft tissue envelope might play an important role on the magnitude of extension center gap and the post-operative knee extension. Furthermore, the center gap in component gap evaluation had higher coefficient of correlation comparing to that in osteotomy gap. Proposed component gap evaluation in soft tissue balance measurement might be more physiological and relevant to the joint condition after TKA, and useful to predict post-operative clinical results

Pseudo-patella baja (PPB) describes narrowing of the distance between the patella and the tibia without shortening of the PT and occurs following Total Knee Arthroplasty (TKA), where the tibial prosthesis plus insert are thicker than the resected tibia. Soft tissue balancing is an important factor in the success of TKA, but if extensive may necessitate the use of thicker tibial inserts with the risk of creating a PPB. Patients who undergo extensive soft tissue releases during TKA, with resultant use of thicker tibial inserts will develop a PPB, with increased risk of patella pathology. 506 patients aged 40-90 years underwent 526 Kinemax TKAs, performed by 7 surgeons in 5 centres between 1999 and 2002. The extent of soft tissue releases and the thickness of tibial inserts were recorded. Pre- and post-operative lateral radiographs were measured by an independent observer, using the Caton-Deshamps method to assess patella position. The patients were assessed using the Oxford Knee Score and the American Knee Society Clinical Rating System, with a minimum follow-up of 12 months. 1. TKA surgery creates a Pseudo-Patella Baja. Excluding patients with a pre-operative patella baja, PPB was introduced into 26.7% of patients. (p=0.000). 2. The incidence of pseudo-patella baja increased with the extent of soft tissue release; Minimal, Moderate or Extensive. (p=0.000). 3. The incidence of pseudo-patella-baja increased with increases in insert thickness. Three groups were identified: Inserts 8 mm, inserts 10-12mm, and inserts 15-22 mm. (p=0.035). There was no correlation between the incidence of PPB and changes in clinical or functional outcome, as measured using the OKS and AKSS. Pseudo-patella baja occurs in 26% of all patients following TKA, and in 46% of patients in whom extensive soft tissue releases have been performed and/or large tibial inserts have been used. At 12 months, no detrimental outcomes were attributable to the incidence of pseudo-patella baja

Introduction. Accurate soft tissue balancing has been recognized as important as alignment of bony cut in total knee arthroplasty (TKA). In addition, using a tensor for TKA that is designed to facilitate soft tissue balance measurements throughout the range of motion with a reduced patello-femoral (PF) joint and femoral component in place, PF joint condition (everted or reduced) has been proved to have a significant effect for intra-operative soft tissue balance. On the other hand, effect of patellar height on intra-operative soft tissue balance has not been well addressed. Therefore, in the present study, we investigated the effect of patellar height by comparing intra-operative soft tissue balance of patella higher subjects (Insall-Salvati index>1) and patella lower subjects (Insall-Salvati indexâ‰/1). Materials and methods. The subjects were 30 consecutive patients (2 men, 28 women), who underwent primary PS TKA (NexGen LPS-flex PS: Zimmer, Warsaw, IN, USA) between May 2003 and December 2006. All cases were osteoarthritis with varus deformity. Preoperative Insall-Salvati index (ISI) was measured and patients were divided into two groups; the patella higher group (ISIï1/4ž1: 18 knees average ISI was 1.12) and the patella lower group (ISIâ‰/1; 12 knees average ISI was 0.94). Component gap and ligament balance (varus angle) were measured using offset-type tensor with 40lb distraction force after osteotomy with the PF joint reduced and femoral trial in place at 0, 10, 45, 90, 135 degrees of knee flexion. Data of two groups were compared using unpaired t test. Results. Component gap was increased from 0 to 90 degrees of knee flexion and decreased at 135 degrees of knee flexion in both groups. Component gaps of the patella higher group in average were 10.9, 14.3, 16.6, 18.2, 16.8 mm at 0, 10, 45, 90, 135 degrees of knee flexion, respectively. Component gaps of the patella lower group in average were 9.6, 13.6, 14.6, 15.5, 14.0 mm at 0, 10, 45, 90, 135 degrees of knee flexion, respectively. When comparing two groups, component gaps of the patella higher group showed larger trend than those of the patella lower group. Especially at 90 and 135 degrees of knee flexion, the patella higher group showed significant larger values than the patella lower group (p<0.05). Varus angles of the patella higher group in average were 2.2ï1/4Œ3.4ï1/4Œ5.0ï1/4Œ5.9ï1/4Œ6.1 degrees at 0, 10, 45, 90, 135 degrees of knee flexion, respectively. Varus angles of the patella lower group in average were 1.7ï1/4Œ2.8ï1/4Œ4.4ï1/4Œ4.9ï1/4Œ4.6 degrees at 0, 10, 45, 90, 135 degrees of knee flexion, respectively. Varus angles of the patella higher group showed slight larger trend than those of the patella lower group, however there was no significant differences between two groups. Discussion. In the present study, the patella higher group showed significant larger component gaps than the patella lower group at high flexion angles (90, 135 degree). This result suggests that smaller pressure on extensor mechanism of the patella higher group has led to larger component gaps at higher flexions. In conclusion, pre-operative measurement of ISI can help surgeons predict intra-operative soft tissue balance

Introduction. Balancing of joint gap is a prerequisite in total knee arthroplasty (TKA). Recently, the tensor has been developed which can measure the joint gap with the patellofemoral joint reduced for more physiological assessment, and the results for osteoarthritis (OA) patients indicated that the flexion gap is larger than the extension gap during posterior-stabilized (PS) TKA. However with respect to the rheumatoid arthritis (RA) patients, the soft tissue balance in TKA is still unknown. Therefore, the purpose of this study was toinvestigate thecharacteristics of thejoint gap during TKAsurgeryforpatients with RA. Methods. We implanted 90 consecutive knees with a PS TKA using a NexGen LPS-flex (Zimmer, Warsaw, IN). OA was the underlying disease in 60 knees and RA was the disease in30 knees. Surgical procedure. We performed all operations with a measured resection technique. The rotational position of the femoral component was determined based on the epicondylar axis of the femur with anterior reference for anteroposterior sizing. Joint gap measurements. After bone cuts and soft tissue balancing, we measured the joint gap with the femoral component in position using seesaw-type tenser device with the patella reduced position after repair of the medial arthrotomy with a few stitches. The center width and asymmetry (tilting) of joint gaps under 40-lb distracting force were measured at 0 degree extension and 90 degrees of knee flexion. Results. The changes in the joint gap from 0 to 90 degrees were 3.2 ± 0.3 mm in OA group and 4.3 ± 0.4 mm in RA group. The increase of joint gap from 0 to 90 degrees in RA was significantly larger than that in OA group (Figure 1). The tilting angle of the joint gap (varus gap expressed as positive values) at 90 degrees of knee flexion in RA group (5.3 ± 0.5 degrees) was significantly larger than that in OA group (2.6 ± 0.4 degrees) (Figure 2). In RA group, there was a positive correlation (r= 0.34, p <0.05) between the increase of joint gap from 0 to 90 degrees and the tilting angle of the joint gap at 90 degrees of knee flexion (Figure 3). Discussion. In this study, the increase of joint gap from 0 to 90 degrees in RA group was significantly larger than that in OA group. In addition, the lateral gap in knee flexion, calculated from the tilting angle of the joint gap, was significantly larger in RA group and was correlated with the increase of joint gap from 0 to 90 degrees of knee flexion. These differences could be attributed to reduced stiffness of the lateral structure, such as lateral collateral ligament and popliteofibular ligament, as well as the extensor mechanism in patients with RA. Therefore, it is necessary to considerthe individual stiffness of soft tissues, together with the applied tension, to decide the rotation of femoral component by reference to the flexion gap during TKA for RA patients

Purpose. Due to the aging population, an increasing proportion of elderly patients with soft tissue sarcoma are presenting to cancer centers. This population appears to have a worse prognosis but the reasons for this has not been studied in depth. The purpose of this study is to examine the effect of age on the outcome of patients with extremity and trunk soft tissue sarcoma. Method. This is a multicenter study including 2071 patients with median age at operation of 57 years (1st quartile–3rd quartile: 42–70). The endpoints considered were local recurrence and metastasis with death as a competing event. Cox proportional hazards models were used to estimate hazard ratios across the age ranges with and without adjustment for known confounding factors. Results. Older patients presented with tumors that were larger and of higher grade. The proportion of positive margins increased progressively as patients aged, but radiation therapy was relatively underused in patients over 60 years old. Age was strongly associated with both local recurrence and metastasis. The 5-year cumulative incidences of local recurrence were 7.6% (4.2%–12.2%) for patients 30 years or younger and 13.8% (9.8%–18.5%) for patients 75 years and older; corresponding 5-year cumulative incidences of metastasis were 21.5% (15.7%–28%) and 32.5% (27%–38.2%) for the same groups. Age showed a non linear effect with a dramatic increase in the risk of local recurrence and metastasis after 60 years old. The increased risk of metastasis for older patients was explained by disparities in tumor characteristics at presentation, and additionally for local recurrence, by disparities in treatment. Conclusion. Age is associated with worse outcomes after resection of soft tissue sarcoma. Older patients have worse outcomes because they tend to present with tumors having more adverse prognostic features and they are also treated less aggressively. A significant effect of age that is not explained by known confounders remains

Introduction. Sheffield Children's Hospital specialises in limb lengthening for children. Soft tissue contracture and loss of range of motion at the knee and ankle are common complications. This review aims to look at therapeutic techniques used by the therapy team to manage these issues. Materials & Methods. A retrospective case review of therapy notes was performed of femoral and tibial lengthening's over the last 3 years. Included were children having long bone lengthening with an iIntramedullary nail, circular frame or mono-lateral rail. Patients excluded were any external fixators crossing the knee/ankle joints. Results. 20 tibial and 25 femoral lengthening's met the inclusion criteria. Pathologies included, complex fractures, limb deficiency, post septic necrosis and other congenital conditions leading to growth disturbance. All patients had issues with loss of motion at some point during the lengthening process. The knee and foot/ankle were equally affected. Numerous risk factors were identified across the cohort. Treatment provided included splinting, serial casting, bolt on shoes, exercise therapy, electrical muscle stimulation and passive stretching. Conclusions. Loss of motion in lower limb joints was common. Patients at higher risk were those with abnormal anatomy, larger target lengthening's, poor compliance or lack of access to local services. Therapy played a significant role in managing joint motion during treatment. However, limitations were noted. No one treatment option gave preferential outcomes, selection of treatment needed to be patient specific. Future research should look at guidelines to aid timely input and avoid secondary complications

Using a tensor for total knee arthroplasty (TKA) that is designed to facilitate soft tissue balance measurements with a reduced patello-femoral (PF) joint, we examined the influence of pre-operative deformity on intra-operative soft tissue balance during posterior-stabilized (PS) TKA. Joint component gap and varus angle were assessed at 0, 10, 45, 90 and 135° of flexion with femoral trial prosthesis placed and PF joint reduced in 60 varus type osteoarthritic patients. Joint gap measurement showed no significant difference regardless the amount of pre-operative varus alignment. With the procedures of soft tissue release avoiding joint line elevation, however, intra-operative varus angle with varus alignment of more than 20 degrees exhibited significant larger values compared to those with varus alignment of less than 20 degrees throughout the range of motion. Accordingly, we conclude that pre-operative severe varus deformity may have the risk for leaving post-operative varus soft tissue balance during PS TKA

Introductions. In cruciate-retaining total knee arthroplasty (TKA), among many factors influencing post-operative outcome, increasing the tibial slope has been considered as one of the beneficial factors to gain deep flexion because of leading more consistent femoral rollback and avoiding direct impingement of the insert against the posterior femur. In contrast, whether increasing the tibial slope is useful or not is controversial in posterior-stabilized (PS) TKA, Under such recognition, accurate soft tissue balancing is also essential surgical intervention for acquisition of successful postoperative outcomes in TKA. In order to permit soft tissue balancing under more physiological conditions during TKAs, we developed an offset type tensor to obtain soft tissue balancing throughout the range of motion with reduced patello-femoral(PF) and aligned tibiofemoral joints and have reported the relationship between intra-operative soft tissue balance and flexion angles. In this study, we therefore assessed the relationship between intra-operative soft tissue balance assessed using the tensor and the tibial slope in PS TKA. Materials and methods. Thirty patients aged with a mean 72.6 years were operated PS TKA(NexGen LPS-Flex, Zimmer, Inc. Warsaw, IN) for the varus type osteoarthritis. Following each bony resection and soft tissue release using measure resection technique, the tensor was fixed to the proximal tibia and femoral trial prosthesis was fitted. Assessment of the joint component gap (mm) and the ligament balance in varus (°)was carried out at 0, 10, 45, 90and 135degrees of knee flexion. The joint distraction force was set at 40lbs. Joint component gap change values during 10-0°,45-0°, 90-0°, 135-0° flexion angle were also calculated. The tibial slopes were measured by postoperative lateral radiograph. The correlation between the tibial slope and values of soft tissue balance were assessed using linear regression analysis. Results. Average joint component gaps were 11.2, 14.7, 16.7, 18.4 and 17.0 mm and ligament balance in varus were 2.2, 2.9, 5.3, 6.8 and 6.9°at 0, 10, 45, 90 and 135° of flexion, respectively. Average joint component gap changes were 3.5, 5.6, 7.2 and 5.7 mm at each range of motion between 10–0, 45-0, 90–0 and 135–0° of flexion, respectively. The mean tibial slope was 5.0(1.6–9.6) degrees. Joint component gap at 90 (R = 0.537, p<0.01),135(R=0.463, p<0.05) degrees of flexion, and joint component gap change value of 90–0° (R = 0.433, p<0.05) showed positive correlations with tibial slope. The other factors assessed in this study showed no correlation with tibial slope. Discussions. The joint gap toward mid-range of flexion might be measured at anterior part of the tibiofemoral joint, whereas the values of joint gap at high flexion where the femur shifted posterior due to femoral rollback were measured the widened posterior part of the joint gap. In addition, extensor mechanism as well as tibial slope might influence joint gap at deep flexion. In conclusion, even PS TKA, increasing the posterior tibial slope resulting in larger flexion gap compared to extension gap should be taken into account for the flexion-extension gap balancing

[Introduction]. It is said that the mechanical stress is a main factor to advance degenerative osteoarthritis. Therefore, to keep the joint stability is very important to minimize mechanical stress. Methods to evaluate bone-related factor are almost established, especially in hip dysplasia. On the other hand, it is unclear how much each soft tissue contribute to the joint stability. In this study we evaluated the soft tissue contribution for hip joint stability by distraction testing using MTS machine. [Materials & Methods]. We used seven fresh frozen hips from four donors, whose race was all western and reason of death was not related to hip disease in all cases. Average age of them at death was 83 years old. Mean average weight and height were each 52 kg and 162 cm. We retrieved hemi pelvis and proximal femur which kept hip joint intact. We removed all other soft tissue except iliofemoral ligament, pubofemoral ligament, ischiofemoral ligament and capsule. The hemi-pelvis mounted on angular-changeable fixator and the femur fixed to MTS machine (Figure 1). XY sliding table was used to minimize the horizontal direction stress during distraction. MTS machine was set to pull the femur parallel to its shaft by 0.4 mm/sec velocity against pelvis after 10N compression and to keep 5 mm distance for 5 seconds. We measured the force at 1 mm, 3 mm, 5 mm distraction. In case the joint was dislocated, the maximum force just before dislocation was recorded. The specimen was changed its posture as neutral (flexion0° abduction0° external rotation0°), flexion (flexion60° abduction0° external rotation0°), abduction (flexion0° abduction30° external rotation0°) and extension (extension20° abduction0° external rotation0°). Each position was measured in six sequential conditions, which are normal, Incised iliofemoral ligament, Circumferentially incised capsule, resected capsule, labral radial tear and resected labrum. After measurement joint surface was observed to evaluate the joint condition. [Results]. We excluded the one specimen two hips by osteoarthritic change of joint surface. The average force needed for 5 mm distraction in normal condition at neutral, flexion, extension and abduction posture was each 95.8N, 52.7N, 162.8N and 94.2N. The force was biggest in extension posture and smallest in flexion posture. The force was statistically reduced from 95.8N to 31.5N after iliofemoral ligament incision in neutral position. The force was also statistically reduced from 145.6N to 31.9N after Circumferential capsule incision in extension posture (Figure 2). In all posture, traction force was reduced after capslotomy and all hip dislocated in all cases. [Discussion]. We could conclude that iliofemoral ligament works much in neutral and extension posture, and capsule helps its work in extension more than in neutral posture. We have reported the zona orbicularis will be important as joint stabilizer before. Capsule including zona orbicularis makes hip joint more stable in any posture because dislocation happened easily after capsule resection in all posture

Introduction:. Soft tissue balancing is a part of every total knee arthroplasty (TKA) surgery. Traditionally, balancing the varus knee has been approached by releasing portions of the medial soft tissue sleeve in a sub-periosteal nature off of the proximal tibia, but this may lead to undue laxity or residual pain about the area the release was performed. More recently, “pie crusting” of the medial soft tissue sleeve has been used to balance the varus knee without compromising the structural integrity of the ligament. This technique may provide advantages over a sub-periosteal release by targeting only medial tight bands that can be palpated with the capsule distracted in 90 degrees of flexion and full extension. This study aims to biomechanically validate the pie crusting technique of the medial soft tissue sleeve and compare the results to those of standard medial releases that have been previously reported. Methods. Six cadaveric TKA specimens were retrieved through the Medical Education and Research Institute (Memphis TN). For each specimen tested, the skin and muscle tissue was removed, and the femur and tibia were cut transversely 180 mm from the joint center. Specimens were fixed in extension in a custom knee testing platform (Little Rock AR) and subjected to a 10 Nm varus and valgus torque. The angle at which these moments occurred was recorded, and each test was repeated for 0, 30, 60, and 90 degrees of flexion. After tests were performed on TKA specimens, a fellowship trained orthopedic surgeon performed “pie crusting,” making alternating stab patterns with a number 11 scalpel blade along the anterior half of the superficial medial collateral ligament (SMCL) or posterior half of the SMCL including the posterior oblique ligament (POL). Three specimens had the anterior capsule pie crusted first and three had the posterior pie crusting performed first, followed by complete pie crusting. After two stages of pie crusting, the medial soft tissue sleeve was released off of the proximal tibia in a sub-periosteal fashion for comparison. Laxity was defined as the angles at which valgus torque equaled 10 Nm. Any increase or decrease in laxity was referenced to the normal TKA laxity. Results:. In full extension, average laxity using complete pie crusting and complete standard ligament release were similar in all flexion angles tested. Pie crusting the anterior half of the medial capsular structures resulted in increased valgus laxity of 3.9 ± 1.6 degrees in 90 degrees of flexion compared to 0.2 ± 2 degrees in full extension. After posterior pie crusting of the medial capsular structures, valgus laxity increased in full extension by 1.8 ± 0.9 degrees with little difference in 90 degrees of flexion. Discussion:. A standard medial collateral ligament release did not cause significantly greater overall valgus laxity compared to pie crusting at any of the flexion angles tested. As previously reported, the anterior half of the SMCL affected laxity in flexion, while the posterior SMCL and POL affected laxity in extension. This knowledge could enable surgeons to make more informed choices when deciding which TKA laxity balancing techniques to use

INTRODUCTION. To obtain appropriate joint gap and soft tissue balance, and to correct the lower limb alignment are important factor to achieve success of total knee arthroplasty (TKA). A variety of computer-assisted navigation systems have been developed to implant the component accurately during TKA. Although, the effects of the navigation system on the joint gap and soft tissue balance are unclear. The purpose of the present study was to investigate the influence of accelerometer-based portable navigation system on the intraoperative joint gap and soft tissue balance. METHODS. Between March 2014 and March 2015, 36 consecutive primary TKAs were performed using a mobile-bearing posterior stabilized (PS) TKA (Vanguard RP; Biomet) for varus osteoarthritis. Of the 36 knees, 26 knees using the accelerometer-based portable computer navigation system (KneeAlign2; OrthAlign) (N group), and 10 knees using conventional alignment guide (femur side; intramedullary rod, tibia side; extramedullary guide) (C group). The intraoperative joint gap and soft tissue balance were measured using tensor device throughout a full range of motion (0°, 30°, 45°, 60°, 90°, 120°and full flexion) at 120N of distraction force. The postoperative component coronal alignment was measured with standing anteroposterior hip-to-ankle radiographs. RESULTS. The mean joint gaps at each flexion angle were maintained constant in N group, and there was a tendency of the joint gap at midflexion ranges to increase in C group. The joint gaps at 30°and 45°of flexion angle in C group were significantly larger than that of in N group. The mean soft tissue balance at 0°of flexion was significantly varus in N group than that of in C group. Postoperatively, in N group, the mean femoral component alignment was valgus 0.1°± 1.3°(range, varus 2°- valgus 3°), the mean tibial component alignment was valgus 1.1°± 1.7°(range, varus 1°- valgus 3°) to the coronal mechanical axis. In C group, the mean femoral component alignment was varus 2.3°± 1.9°(range, varus 6°- valgus 1°), the mean tibial component alignment was valgus 2.0°± 1.3°(range, 0°- valgus 5°) to the coronal mechanical axis. There was statistically significant difference in femoral component alignment, there was no statistically significant difference in tibial component alignment. DISCUSSION AND CONCLUSION. The present study demonstrated that navigation-assisted TKA was prevented the joint gaps from increasing at 30°and 45°of flexion. However, it was difficult to achieve soft tissue balance at extension. In conventional TKA, the femoral component alignment was usually varus. In contrast, accelerometer-based portable navigation system is superior to implant the femoral component accurately. However, there were several cases that femoral component alignment is valgus because of a variation in the accuracy of this navigation system. Surgeons should be aware of difficulty to accomplish all of appropriate joint gap and soft tissue balance, and lower limb alignment in navigation-assisted TKA

Distal femur resection for correction of flexion contractures in total knee arthroplasty (TKA) can lead to joint line elevation, abnormal knee kinematics and patellofemoral problems. The aim of this retrospective study was to establish the contribution of soft tissue releases and bony cuts in the change in maximum knee extension in TKA. Data were available for 209 navigated TKAs performed by a single surgeon using a medial approach. All patients had the same cemented implant, either CR or PS, which both required a minimum thickness of 10 mm for the tibial and 9mm for the femoral component. Intra-operatively pre- and post-implant extension angles and the size of bone resection were collected using a commercial navigation system. The thickness of polyethylene insert and the extent of soft tissue release performed (no release, moderate and extensive release) were collected from the patient record. A univariate linear regression model was used to predict change in maximum extension from pre- to post-implant. The mean bone resection was 19mm (15 to 28 mm) (Figure 1).79% of polyethylene inserts were 10mm thick (10 to 16 mm). 71% of knees had no soft tissue release. The mean increase in extension was 5° (11° decrease to 23° increase) (Figure 1). The analysis showed that bone cuts (p<0.001), soft tissue release (p=0.001) and insert thickness (p=0.010) were all significant terms in the model (r. 2. adj. =0.170). This model predicted that carrying out a TKA with 19mm bone cuts, 10mm insert and no soft tissue release would give 4.2° increase in extension. It predicted that a moderate release would give a 2.8° increase in extension compared to no release, with an extensive release giving 3.9° increase over no release. For each mm increase in bone cuts the model predicted a 0.8° increase in extension and for each mm increase in insert size a decrease extension by 1.1°. Preoperative FFC contracture is a frequent condition in TKA that the surgeon has to address either by resecting more bone or by extending soft tissue release to increase the extension gap to fit the knee implant. This analysis of 209 navigated knee arthroplasty showed that both options are suitable to increase the extension gap. The modelling results show that in general to increase maximum extension by the same as an extensive soft tissue release that bone cuts would have to be increased by 4–5mm. However this model only accounted for 17% of the variation in change in extension pre- to post-implant so is poor at predicting outcomes for specific patients. The large variation in actual FFC correction indicates that this relies on factors other than bone cuts and soft tissue releases as quantified in this study

Aim. To assess the risk of hip dislocations in children with cerebral palsy (CP) attending special schools, and the effects of preventative soft tissue surgery (psoas and adductor tenotomy). Method. 110 children were reviewed from 1985-2000. Severity of CP was graded according to the Gross Motor Function Classification System (GMFCS). Hemiplegics - grade 1, Diplegics grades 2 & 3, Quadriplegics grades 4 & 5. Patients were grouped into age groups 5, 10 and 15 years and the number of hip dislocations in each group were noted. Numbers of patients who had preventative soft tissue surgery was also noted. Indication for surgery, >35% femoral head uncovering. Results. Percentage of dislocations increased with CP severity. At 15 years, no dislocations in GMFCS 2, 6% GMFCS 3, 19% GMFCS 4 and 40% in GMFCS 5. The number of patients with at least 1 hip dislocation increased with age at all age groups. GMFCS 4 (age 5 yrs 9%, age 10 yrs 20% and 15 yrs 30%). GMFCS 5 (age5 yrs 22%, age 10 yrs 48% and age 15 yrs 50%). By 15 years, 54 hips in GMFCS 2 & 3 (diplegics), preventative soft tissue surgery had not reduced chances of hip dislocation; only 1 dislocated (2%). In GMFCS 4 & 5 (quadriplegics), dislocations reduced from 40% in those without surgery to 26% in those who had preventive soft tissue surgery. This was particularly so in GMFCS 5 where there was a reduction from 83% dislocation without surgery to 33% with soft tissue preventive surgery. Conclusions. Preventive soft tissue surgery was effective in reducing the rate of hip dislocation in quadriplegic CP especially GMFCS 5

Introduction. Appropriate intraoperative soft tissue balancing is recognized to be essential in total knee arthroplasty (TKA). However, it has been rarely reported whether intraoperative soft tissue balance reflects postoperative outcomes. In this study, we therefore assessed the relationship between the intra-operative soft tissue balance measurements and the post-operative stress radiographs at a minimum 1-year follow-up in cruciate-retaining (CR) TKA, and further analyzed the postoperative clinical outcome. Methods. The subjects were 25 patients diagnosed with osteoarthritis with varus deformity and underwent primary TKA. The mean age at surgery was 72.0 ± 7.5 years (range, 47–84 years). The Surgeries were performed with the tibia first gap technique using CR-TKA (e motion, B. Braun Aesculap) and the image-free navigation system (Orthopilot). We intraoperatively measured varus ligament balance (°, varus angle; VA) and joint component gap (mm, center gap; CG) at 10° and 90° knee flexion guided by the navigation system, with the patella reduced. At a minimum 1-year follow-up, post-operative coronal laxity at extension was assessed by varus and valgus stress radiographs of the knees with 1.5 kgf using a Telos SE arthrometer (Fa Telos) and that at flexion was assessed by epicondylar view radiographs of the knees with a 1.5-kg weight at the ankle. After calculating postoperative VA and CG from measurements of radiographs, measurements and preoperative and postoperative clinical outcome, such as Knee Society Clinical Rating System (Knee score; KSS, Functional score; KSFS) and postoperative knee flexion, were analyzed statistically using linear regression models and Pearson's correlation coefficient. Results. The mean follow-up duration was 22.0 months (range, 12–36 months). The average pre-operative KSS and KSFS was 57.0 points and 62.8, respectively, and the average post-operative scores were 98.4 points and 91.5, respectively. The both scores were significantly improved. The mean preoperative knee flexion angle was 121.8°, and postoperative knee flexion angle was 124.8°.ã��The mean pre- and post-operative joint component gaps at extension and flexion were 14.4 and 14.4 mm, and 15.6 and 16.5 mm, respectively. The mean pre- and post-operative values of varus ligament balance at extension and flexion were 2.5° and 2.7°, and 1.7° and 4.4°, respectively. Regression analysis revealed that the intraoperative CG was positively correlated with the postoperative CG at both extension and flexion (R = 0.45, P < 0.05; R = 0.52, P < 0.05, respectively) and intraoperative VA was positively correlated with the postoperative VA at extension (R = 0.52, P < 0.05) (Figure 1). Furthermore, postoperative flexion angle was positively correlated with the postoperative CG and VA at flexion (R=0.43, p<0.05, R=0.44, p<0.05, respectively) (Figure 2). Conclusion. We revealed that intraoperative soft tissue balance reflect postoperative soft tissue balance in CR-TKA. Furthermore, postoperative lateral laxity at flexion may permit the improvement of postoperative flexion angle

The various disorders of the patellofemoral joint, from pain syndrome to maltracking and arthritis, form a significant subset of knee disorders (Callaghan and Selfe 2007). Several studies have shown significant geography and gender based variation in incidence rates of these disorders and of osteoarthritis in general (Woolf 2003). A number of previous studies have examined patellar shape in this context, focusing primarily on the use of 2D measurements of bony geometry to classify patellar shapes and identify high-risk groups (Baumgartl 1964; Ficat 1970). Recent developments in imaging and statistical analysis have enabled a more sophisticated approach, characterised by statistical shape models which account for three dimensional shape differences (Bryan 2008). Incorporating soft tissue data into these analyses, however, has been a challenge due to factors including the necessity of multi-modality images, absence of repeatable landmarks, and complexity of the surfaces involved. We present here a novel method which has potential to significantly improve analysis of soft tissue geometry in joints. It is built using Arthron, a UCD-developed biomechanics analysis software package. The shape modelling process consists of three phases: pre-processing, consistent surface parameterization, and statistical shape analysis. The pre-processing phase consists of several mesh processing operations that prepare the input surfaces for shape modelling. Consistent surface parameterizations are implemented using the minimum description length (MDL) correspondence method (Davies 2002) [Fig. 1]. The statistical shape analysis phase involves the reporting and visualization of geometric variation at the input surface. An algorithm was developed to measure the cartilage thickness at each node on the patellar surface mesh. The initial step in this process was to calculate surface normal vectors at each point. These vectors were then projected through the cartilage surface model in order to calculate the thickness [Fig. 2]. The Matlab software was used to aggregate all cartilage thickness values in a given subgroup and after being normalised for the average patellar centroid size for the subgroup, these thicknesses were visualised on the average shape. Pilot study data consisted of 19 Caucasian (7 female, 12 male) and 13 Japanese (7 female, 6 male) subjects. These data originated from studies performed by DePuy Orthopaedics Inc. Initial results show ethnicity effects in cartilage thickness to be more significant than gender effects [Fig. 3]. After correcting for patellar centroid size, male subjects display 9% greater average thickness than female subjects, while Caucasian subjects display 17% greater average thickness than Asian subjects. Areas of statistically significant differences (t < 0.05) were found to coincide with expected areas of patellofemoral contact through the flexion cycle, showing the potential for the thickness differential to impact upon patellar kinematics. Principal component analysis of the thickness distributions gives more detailed information about modes of variation. With further development, this method has potential to enable sophisticated analysis of localised variation in soft tissue geometry, thereby improving understanding of the impact of joint geometry on disease formation