Pedicle screw fixation commonly uses a manual probe technique for preparation and insertion of the screw. However, the accuracy of obtaining a centrally located path using the probe is often dependent on the experience of the surgeon and may lead to increased complications. Fluoroscopy and navigation assistance improves accuracy but may expose the patient and surgeon to excessive radiation. DSG measures electrical conductivity at the tip and provides the surgeon with real-time audio and visual feedback based on differences in tissue density between cortical and cancellous bone and soft tissue. The authors investigated the effectiveness of DSG for training residents on safe placement of pedicle screws. 15 male cadaveric thoracolumbar spine specimens were fresh-frozen at the time of expiration. Residents were assigned 3 specimens each and randomised by pedicle side and order of technique for pedicle screw placement (free-hand versus DSG). Fluoroscopy and other navigation assistance were not used for pedicle preparation. All specimens were imaged using CT following insertion of all pedicle screws. The accuracy was assessed by a senior radiologist and graded as within (≤ 2mm breach) or outside (> 2mm breach) the pedicle.Introduction
Methods
When performing total knee arthroplasty (TKA), surgeons often utilize a posterior-stabilized (PS) design which compensates for the loss of the posterior cruciate ligament (PCL). These designs attempt to replicate normal knee kinematics and loading using a cam and post to provide posterior restraint of the tibia during flexion. However, these designs may not be able to compensate for the increase in flexion space or the inherent loss of coronal stability after PCL release compared to a cruciate retaining (CR) design. This study aimed to compare stability of PS and CR TKA designs by assessing laxity in three planes. The specimens utilized in this study were lower extremities from fresh cadavers of donors who had previously undergone a total knee replacement (Medical Education and Research Institute (Memphis, TN) and Restore Life USA (Johnson City, TN)). IRB approval was obtained prior to performing the study. Twenty-three knee specimens (8 left, 15 right) were retrieved and all skin, subcutaneous tissue and muscle was removed. The femur and tibia were cut transversely 180 mm superior and inferior to the knee joint line, respectively, and specimens were mounted in a custom knee testing machine. Specimens were tested with the knee joint at full extension and at 30, 60, and 90 degrees of flexion. Laxity was assessed at 1.5 Nm of internal and external torque and 10 Nm varus and valgus torque, as well as a 35 N anterior and posterior force. Laxity was expressed as degrees of tibial displacement in the coronal plane under a varus/valgus torque and degrees of displacement in the transverse plane under an internal/external torque, as well as mm of anterior or posterior displacement. TKA components were retrieved to determine PS or CR design and grouped accordingly.Introduction
Methods
The sit-to-stand (STS) movement is a physically demanding activity of daily living and is performed more than 50 times per day in healthy adults. Several studies have shown that the normal ‘screw-home’ mechanism is altered after total knee arthroplasty (TKA). However, these studies have been criticized due to their limitations of the movement being non-weight-bearing or atypical daily activity (lunge maneuver). We analyzed TKA subjects during a STS activity to determine if the internal-external rotation of their TKA knees differed from the knees of control subjects. Six TKA subjects (3 M, 3 F) participated following institutional review board approval and informed consent. One subject had bilateral knee replacement. Surgery was performed by the same surgeon using the same type of implant (6 posterior-stabilized, 1 cruciate-retaining). The control group included eight healthy subjects (6 M, 2 F). Retro-reflective markers were placed over bony landmarks of the torso, pelvis, and lower extremities, and arrays of four markers were attached to the thighs and shanks using elastic wrap. A digitizing pointer was used to create virtual markers at the anterior superior iliac spines. A nine camera video-based opto-electronic system (Qualisys) was used for 3D motion capture. Subjects were barefoot and seated on a 46 cm armless bench with one foot on each force plate (AMTI). Subjects rose from their seated position, paused, and returned to the seated position at a self-selected pace repeatedly for 30 seconds. Subjects did not use their arms to push off the bench. Only the STS portion of the task was analyzed. The start of the STS cycle was defined when the C7 marker began to move forward in the sagittal plane and ended at the point of maximum knee extension. Only the right leg of the control subjects was used for analysis.Introduction
Materials and Methods
In a previous study of subjects with no history of lower extremity injury or disease we found a linear relationship between body weight and peak hip, knee, and ankle joint forces during the stance phase of gait. To investigate the effect of total knee arthroplasty (TKA) on forces in the operated joints as well as the other joints of the lower extremities, we tested TKA subjects during gait and performed inverse dynamics analyses of the results. TKA subjects (3 M, 1 F; 58 ± 5 years; body mass index range (BMI): 26–36 kg/m2) participated in this investigation following institutional review board approval and informed consent. One subject had bilateral knee replacement. Each patient received the same implant design (4 PS, 1 CR). Data from previously tested control subjects (8 M, 4 F; 26 ± 4 years; BMI: 20–36 kg/m2) were used for comparison. Retro-reflective markers were placed over bony landmarks of each subject. A nine-camera video-based opto-electronic system was used for 3D motion capture as subjects walked barefoot at a self-selected speed on a 10 meter walkway instrumented with three force plates. Data were imported into a 12-body segment multibody dynamics model (AnyBody Technology) to calculate joint forces. Each leg contained 56 muscles whose mechanical effect was modeled by 159 simple muscle slips, each consisting of a contractile element. The models were scaled to match each subject's anthropometry and BMI. For the control subjects, only one limb was used in determining the relationship between body mass and peak joint force at the hip, knee, and ankle. For the TKA subjects, the peak joint forces were calculated for both the TKA limb and the contralateral limb.Introduction
Materials and Methods
Loss of muscle mass (sarcopenia) and function in ageing are associated with reduced functional ability, quality of life and reduced life expectancy. In cancer patients, age related muscle loss may be exacerbated by cachexia and poor nutritional intake. Individuals with widespread disseminated disease are most prone to increasing functional decline, increased morbidity and accelerated death. However subjective assessments of physical performance have been shown to be poor indicators of life expectancy in these patients. To develop an objective measure to aid calculation of life expectancy in cancer by investigating the association between objectively measured lean muscle mass and longevity, in 41 patients with known spinal metastases from all cause primaries.Background
Aims
Repair of the arthrotomy is a performed at the end of every total knee arthroplasty (TKA). After the arthrotomy is performed, most surgeons attempt to close the arthrotomy with the medial and lateral edges anatomically approximated. If no landmarks are made prior to performing the arthrotomy however, there is a risk that anatomic approximation may not be obtained. This study looked into the biomechanical changes in stiffness of the knee before and after a medial parapatellar approach repaired with an anatomic, and shifted capsular repair with the medial side of the arthrotomy shifted up or down when repaired to determine if capsular closure may have an effect on the stiffness of the joint. Fourteen 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 and a 1.5 Nm internal and external rotational 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 retrieved TKA specimens, a fellowship trained orthopedic surgeon vented the knee capsule by making an incision with a number 10 scalpel blade in a horizontal nature to provide a landmark for anatomic reapproximation. Tests were repeated as before, after which the surgeon performed a standard arthrotomy and repaired it using #0 suture and a neutral alignment. Sutures were cut and the repair was repeated using upward 5 mm shift and downward 5 mm shift of the medial side of the arthrotomy during the repair. All tests were repeated after each repair technique. Any increase or decrease in laxity after capsule repair was referenced to the TKA laxity tested prior to an arthrotomy being performed.Introduction:
Methods:
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. 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.Introduction:
Methods
Soft tissue balancing during Total Knee Arthroplasty (TKA) is a step every surgeon takes during surgery. Coronal and transverse plane mechanical alignment is another parameter that surgeons address during surgery in an attempt to decrease wear and increase longevity. To date, a correlation between laxity, component wear patterns, and alignment of the tibial and femoral implant components has not been established. Theoretically, suboptimal alignment and poor soft tissue balancing should increase polyethylene wear and decrease implant survivorship, contributing to implant loosening and costly revision surgeries. This study utilizes a retrieval program of functioning TKAs obtained at the time of necropsy. By utilizing CT scans, mechanical laxity testing, and polyethylene damage scores, we aimed to determine if any correlation between proper alignment and ligament balancing to polyethylene damage scores exists. Computed Tomography (CT) scans were performed on 17 cadaveric knees containing TKAs obtained from the Medical Education and Research Institute (Memphis TN) using a GE Brightspeed scanning system with a 1.25 mm slice thickness. Transverse slices from these scans were used to calculate the femoral and tibial component rotation for each specimen. Component rotation was determined by utilizing previously published methods (Berger et al), and component mismatch was defined as the difference in rotation angles of the femoral and tibial components. After removal of skin, subcutaneous and muscle tissue, the tibia and femur of each leg was cut transversely, and the specimens were mounted in a custom knee testing machine (Little Rock, AR). Specimens were subjected to a 10 Nm varus and valgus torque and a 1.5 Nm internal and external rotation torque. Data was continuously recorded, and the angle or displacement at each torque or force was noted. Each test was performed at full extension and 30, 60, and 90 degrees of flexion. TKA components were then removed from the cadaveric knees, cleaned of PMMA, and visually inspected for wear using a grading system with 10 wear areas on the articulating surface of the polyethylene tibial insert (Hood et al). Scores were assigned based on severity of 7 different degradation characteristics, and were separated based on medial or lateral compartment. The maximum possible total score was 210 for each knee. The average length of TKA implantation was 10 years. The coronal angle at +10 Nm (varus) moment ranged from 5 to 12 degrees, while the angle under a −10 Nm (valgus) moment ranged from 7 to 11 degrees across 10 specimens. The average component rotational mismatch was 20.5 degrees. The average overall medial wear score was 8.8, while the lateral average was 9.6. Wear scores showed a higher correlation to laxity in the medial compartment than the lateral side (Figures 1 and 2).Methods:
Results:
High energy chest trauma resulting in flail chest injury is associated with increased rates of patient morbidity. Operative fixation of acute rib fractures is thought to reduce morbidity by reducing pain and improving chest mechanics enabling earlier ventilator weaning. A variety of operative techniques have been described and we report on our unit's experience of acute rib fracture fixation. Over 18 months, 10 patients have undergone acute rib fracture fixation. Outcome measures included; patient demographics, time ventilated pre-operatively, time ventilated post-operatively and time spent on ITU/HDU post operatively. The mean time from presentation to surgery was 5 days (range 2–12 days). The mean time ventilated post operatively was 2 days (range 1–4 days) and the mean number of days spent on ITU/HDU post-operatively was 6 days (range 2–11 days). Our results appear positive in terms of time spent ventilated post-operatively but no conclusion can be drawn as we have no comparable non-operative group. We have however shown, that rib fracture fixation can be carried out successfully and safely in a trauma centre. Further evidence on rib fracture fixation is required from a large, multi-centre randomised controlled trial.
It is thought that socioeconomic status and cultural upbringing influence the patient based outcomes of total joint arthroplasty. Previous studies have shown that patients in a lower socioeconomic class had surgery at an earlier age, increased comorbidities, increased severity of symptoms at presentation, and less satisfaction with the outcome. The purpose of this study was to compare the 1) reasons for undergoing total joint replacement and 2) satisfaction with the outcome among patients in different cultures and socioeconomic categories. We hypothesized that the overall reasons for undergoing surgery would be similar among all groups. Patients undergoing total hip or knee arthroplasty were divided into groups based on their country of residence and socioeconomic status. The patients were asked to rank their reasons for undergoing surgery preoperatively from 1 to 4 according to importance. They were also asked to state how much relief of pain or improvement in function they expected to obtain. They were then asked to complete a questionnaire assessing their satisfaction with surgery 6 months post-operatively. These results were then compared across the three groups.Introduction
Method
Magnetic resonance imaging (MRI) scans are widely used in the assessment of knees, often prior to arthroscopic procedures. The reporting of chondral damage on MRI scans can be variable. The correlation between MRI reports of chondral damage and that found at arthroscopy is often inconsistent. The aim of this study was to identify how well MRI reports correlated with the extent of chondral damage found at arthroscopy. A retrospective case-note review of a single-surgeon series of 175 arthroscopic procedures was performed. 83 patients were included in the study. The remainder were excluded if an MRI scan had not been performed, or had been performed more than 3 months prior to surgery. The condition of the articular cartilage demonstrated by MRI was compared to that found at arthroscopy. Data was analysed for presence and extent of chondral damage. Comparison between MRI and arthroscopy findings showed high Specificity (90%) and Negative Predictive Values (89%) for chondral damage, but low Sensitivity (46%). Cohen's kappa values < 0.2 revealed very poor correlation for the extent of damage. This study demonstrates that MRI is good at describing whether articular damage is present but does not reliably describe the extent of the damage.
Shoulder pain represents a significant burden of disease in the general population, yet there is a lack of evidence about the effectiveness of routinely used interventions. Current management of ‘painful arc’ of the shoulder in Primary Care is not evidence-based. Over a six-month period patients with ‘painful arc’ of less than six months duration were recruited via their GPs. Eligible patients were consented to enter the trial and were then randomised, by sealed envelopes, to one of four arms of the study: control (normal analgesia and/or non-steroidal anti-inflammatory medication), a specified and repeatable Exercise and Manual Therapy Package (EMTP), a course of up to three subacromial steroid injections or both the EMTP and the steroid injections. The interventions and clinic follow-ups were over an 18-week period. A final postal questionnaire was sent out at one year. The progress of the patients was monitored using the Oxford Shoulder Score (OSS) and the SF36 general health questionnaire. Seventy-nine GPs referred 186 patients, of whom 112 were randomised (Control=27, EMTP=29, Injections=28, Both=28). 64 patients were female and 48 male. The mean age was 54.5 years (range 23-88 years). Ninety patients completed the trial (Control=20, EMTP=22, Injections=26, Both=22). Sixty-two returned the follow-up questionnaire. By paired sample t-tests, no significant differences were found between the OSS scores or SF-36 (physical health total) at the beginning and end of the intervention period, or at one year, in any group. There were no differences in changes in scores between groups. Two patients in the injection group went on to surgery, along with one each in the control and EMTP groups. We have found no significant differences in outcome between steroid injections, a physiotherapy package, both treatments, or symptomatic treatment in our group of patients presenting with symptoms of painful arc of the shoulder.
