Soft tissue balancing during total knee arthroplasty (TKA) has a direct affect on patello-femoral tracking and knee range of motion, which are necessary for a well functioning TKA postoperatively. We report on the use of an electronic pressure sensing instrument for soft tissue balancing of the knee before completion of all intraoperative bone cuts, as a way to improve patellar tracking. In a retrospective study of 99 consecutive TKAs, with intraoperative electronic instrument guided soft tissue balancing performed, a reduction in the incidence of lateral patellar retinacular release was found, as compared with the 100 consecutive TKAs prior to its use (5.5% v 12%, respectively). Electronic measurement of soft tissue balancing during TKA reduced the need for lateral patellar retinacular release.

A fracture construct, representing a worst-case model of a comminuted intertrochanteric fracture, was created in order to compare the fxation stability of two different cephalomedullary nails: one where the lag screw can telescope within itself to achieve displacement of the head-neck fragment, and the other where the solid lag screw slides only. After nail fxation, the models were loaded and then cycled, and positions of the head-neck fragment and lag screw were determined. Both nails similarly acted to limit motion of the head-neck fragment by the sliding of their lag screws, causing impingement of the fragment against the nail. Fragment movement was achieved with signifcantly less force with the telescoping lag screws, which also showed no fnal lateral projection from the nail. This was in contrast to the solid lag screws that demonstrated lateral projection in all cases.

Hip resurfacing arthroplasty has been developed as an alternative to traditional total hip arthroplasty, in an effort to minimize the loss of native bone in young patients with symptomatic hip osteoarthritis. Femoral neck fracture fol- lowing hip resurfacing is a unique complication; several risk factors are associated with this complication, including female gender. In the present study, we used fnite element models of the proximal femur to simulate stresses across the femoral neck in pelvis models with varying widths. This analysis demonstrated an increase in hip reaction forces as the width of the pelvis increases, a condition that simulates a resurfacing condition in a female pelvis. This difference in peak stress on the femoral neck may explain the increased incidence of femoral neck fractures seen in female patients following hip resurfacing.

Pedicle screws (PS) can provide initial stabilization of anterior interbody femoral ring allograft (FRA) lumbar constructs. Translaminar screws (TLS) have also been ad- vocated for this procedure. The objective of this study was to use an in vitro human cadaveric model to compare the stability of one-level anterior interbody lumbar constructs stabilized with PS and those stabilized with TLS. Five human cadaveric spinal motion segments (L4-S2) were biomechani- cally evaluated in the intact condition and using the follow- ing methods of stabilization: anterior interbody fusion with FRA, anterior FRA supplemented with PS, and anterior FRA supplemented with TLS. Stability was determined for each construct by measuring construct displacement as a function of applied load under the following conditions: compression, fexion, extension, lateral bending to each side, and axial torsion. There were no statistically signifcant differences in construct stability between FRA supplemented with PS and FRA supplemented with TLS under any of the loading conditions. In selected cases, supplementation of anterior femoral ring allograft with translaminar screws is a viable alternative to supplementation with pedicle screws.

Purpose. It is somewhat surprising that radiographic criteria for lumbar stenosis have been transposed from radiography and CT to MR without scientific validation. As these radiographic criteria were developed via population studies with criteria defned by two standard deviations from the mean, we sought to perform the same methodology via MR. Methods. The study was approved by the institutional review board; the requirement for informed consent was waived. One-hundred patients referred for possible metastatic disease, aged 4 to 94 were studied. Measurements were obtained on a midline sagittal T2-weighted (6000/120) image at each disc level, as well as at the mid-vertebral level. The distributive mean, and standard deviations were calculated and -2 SD was used as a “cutoff” for spinal stenosis. To assess for interobserver variation, 20% of the measurements were repeated by a second observer. To assess for intraobserver variation, another 20% of the measurements were repeated a second time at a minimum of a two month interval. Results. The spinal canal was narrowest at L5-S1 (mean: 1.16 cm), and widest at L1-L2 (mean: 1.56 cm). Overall the narrowest measurements were at the intervertebral disc space and were narrower at the lower disc spaces. In our population, the lowest cutoff limit (two standard deviations below the mean) had a range between 0.38 cm at the L3-L4 disc space and 0.9 cm at the L1 vertebral level. Notably at the L3 level the size range was from 0.77 to 1.75 Conclusion. Traditional measurements of canal diameters may be too large when applied to soft tissue analysis on MR. We suggest using a cutoff of smaller than 0.90 cm for developmental stenosis.

Orthopaedic patients with poor nutritional status are at an increased risk of postoperative complications, such as infection and wound healing. Nasal colonization with Staphylococcus aureus, especially with methicillin-resistant Staphylococcus aureus, has been shown to be a risk factor for surgical-site infections. We examined the incidence of nutritional depletion in our arthroplasty population and its correlation with Staphylococcus aureus colonization. We conducted a retrospective review of prospectively collected data of our arthroplasty patient population. Patients with known Staphylococcus aureus colonization or surgical-site infection were compared with a random cohort of patients. Patient demographics, preoperative nasal culture, and two nutritional screening scores were collected. Six hundred and ffty-two patients underwent arthroplasty and completed preoperative nasal cultures and nutritional assessment. A high percentage (27%) of our patients demonstrated some level of nutritional depletion prior to joint replacement. Overall nutritional scores were not signifcantly associated with surgery-type, preoperative nasal culture, or surgical- site infection in our patient population.

Background. Although the effect of Staphylococcus aureus (SA) decolonization on surgical site infection (SSI) rates has been studied, patient tolerance and acceptance of these regimens has not been assessed. Surgical patients at our hospital’s Pre-Admission Testing Clinic (PAT) receive SA reduction protocols instructing the preoperative use of chlorhexidine gluconate (CHG) soap and intranasal mupiro- cin ointment (MO). Certain insurers do not cover MO costs resulting in out of pocket (OOP) expenses for some patients. Objective. This study assessed patient attitudes and compliance with our hospital’s SA decolonization regimen. Methods. One-hundred-forty-six patients received sur- veys. Descriptive statistics were used for analysis. Results. Of respondents ftting inclusion criteria, 81% followed the MO protocol (MO users) while 89% followed the CHG protocol (CHG users). Fifty-four percent of MO users reported OOP expenses and 13% reported a hard or very hard fnancial burden. Ninety-three percent of CHG users reported the protocol was easy or very easy to follow. Conclusion. Eighty-one percent of patients receiving the SA protocol were fully compliant despite cost or diffculty obtaining MO. Given these barriers and some diffculty with CHG application, we hypothesize compliance may be im- proved if MO is provided to patients without OOP expenses and if the CHG application method is simplifed.

Background. Traditional surgical treatment of isthmic spon- dylolisthesis is posterior-lateral fusion, but the addition of anterior surgery has been explored. The purpose of this study was to evaluate the surgical and clinical outcomes of anterior-posterior surgical treatment for low-grade isthmic spondylolisthesis. Methods. Retrospectively, we enrolled 23 consecutive patients (mean age of 50) who underwent surgical treatment for low grade isthmic spondylolisthesis. The mean follow-up was 10 months. Basic demographic and radiographic data was collected. Pre- and post-surgical clinical surveys (VAS, ODI, and SF-36) were collected. Results. All 23 patients underwent anterior interbody fusion with a femoral ring allograft or ICBG in combina- tion with posterior lumbar decompression and fusion with instrumentation. The average slip percentage decreased from 23.2% to 19.0% (p = 0.24) while slip angle increased from 9.8° to 17.9° (p < 0.001) and average disc height decreased from 1.9 cm to 0.80 cm (p < 0.001). VAS scores decreased from 7.1 to 2.4 (p < 0.001), ODI scores decreased from 52.5 to 28.1 (p < 0.001), and SF-36 scores increased in the Physical Component Scale (PCS) from 29.5 to 42.6 (p < 0.001). Conclusion. In our study, patients demonstrated an im- provement in the ODI as well the physical component scores of the SF-36, thus having a good clinical outcome.

Spontaneous osteonecrosis of the knee (SPONK) and osteo- necrosis in the postoperative knee (ONPK) are two clinical entities that have the potential to cause signifcant morbid- ity in affected patients. In addition to the knowledge of the patient population at risk and the classic presentation and imaging characteristics of SPONK and ONPK, the treat- ing orthopaedic surgeon needs to maintain a high index of suspicion for these disorders since early diagnosis and treatment may allow for an improved clinical outcome. The following review presents the current knowledge regarding these two pathological processes of the knee.

Alkaptonuria is a rare disease in which a defciency in the homogentisate 1, 2-dioxygenase enzyme results in a buildup of homogentisic acid. Ochronosis, the deposition of excess homogentisic acid in connective tissue, causes brownish-black pigmentation and weakening of the tissue ultimately resulting in chronic infammation, degeneration, and osteoarthritis. There is currently no defnitive cure for alkaptonuric ochronosis, and management is usually symp- tomatic. However, total joint replacements in severe cases of ochronotic osteoarthritis have comparable outcomes to osteoarthritic patients without ochronosis. We report a case of a patient with ochronotic arthritis of the knee treated with total knee arthroplasty.

Intraarticular coronal fracture of the femoral condyle is rare, and an isolated medial Hoffa fracture in a child is extremely rare. To our knowledge, such a case has not yet been reported in the literature. Early diagnosis and prompt treatment are essential for a good long-term outcome. We report a case of 12-year-old male who suffered a traffc accident and sustained an isolated medial Hoffa fracture. Open reduction was performed using a subvastus approach and the joint surface congruity restored and secured by two large fragment partially threaded screws placed from anterior to posterior in the epiphysis. At the 36-month follow-up, the fracture was united, and the patient had full extension and approximately 130° fexion of knee. There was no varus or valgus instability or limb length discrepancy. This case highlights the importance of early diagnosis and prompt treatment in the form of epiphyseal fxation for the management of these fractures in skeletally immature individuals.

The incidence of isthmic spondylolysis is approximately 3% to 6% in the general population. Spondylolytic defects involving multiple vertebral levels, on the other hand, are extremely rare. Only a handful of reports have examined the outcomes of surgical treatment of multi-level spondylolysis. Here, we present one case of bilateral pars defects at L3, L4, and L5. The patient, a 46-year-old female, presented with lower back pain radiating into the left lower extremity. Radiographs and CT scans of the lumbar spine revealed bilateral pars defects at L3-L5. The patient underwent lumbar discectomy and interbody fusion of L4-S1 as well as direct repair of the pars defect at L3. There were no postoperative complications, and by seven months the patient had improved clinically. While previous reports describe the use of either direct repair or fusion in the treatment of spondylolysis, we are unaware of reports describing the use of both techniques at adjacent levels.

Soft tissue balancing during total knee arthroplasty (TKA) has a direct affect on patello-femoral tracking and knee range of motion, which are necessary for a well functioning TKA postoperatively. We report on the use of an electronic pressure sensing instrument for soft tissue balancing of the knee before completion of all intraoperative bone cuts, as a way to improve patellar tracking. In a retrospective study of 99 consecutive TKAs, with intraoperative electronic instrument guided soft tissue balancing performed, a reduction in the incidence of lateral patellar retinacular release was found, as compared with the 100 consecutive TKAs prior to its use (5.5% v 12%, respectively). Electronic measurement of soft tissue balancing during TKA reduced the need for lateral patellar retinacular release.

A fracture construct, representing a worst-case model of a comminuted intertrochanteric fracture, was created in order to compare the fxation stability of two different cephalomedullary nails: one where the lag screw can telescope within itself to achieve displacement of the head-neck fragment, and the other where the solid lag screw slides only. After nail fxation, the models were loaded and then cycled, and positions of the head-neck fragment and lag screw were determined. Both nails similarly acted to limit motion of the head-neck fragment by the sliding of their lag screws, causing impingement of the fragment against the nail. Fragment movement was achieved with signifcantly less force with the telescoping lag screws, which also showed no fnal lateral projection from the nail. This was in contrast to the solid lag screws that demonstrated lateral projection in all cases.

Hip resurfacing arthroplasty has been developed as an alternative to traditional total hip arthroplasty, in an effort to minimize the loss of native bone in young patients with symptomatic hip osteoarthritis. Femoral neck fracture fol- lowing hip resurfacing is a unique complication; several risk factors are associated with this complication, including female gender. In the present study, we used fnite element models of the proximal femur to simulate stresses across the femoral neck in pelvis models with varying widths. This analysis demonstrated an increase in hip reaction forces as the width of the pelvis increases, a condition that simulates a resurfacing condition in a female pelvis. This difference in peak stress on the femoral neck may explain the increased incidence of femoral neck fractures seen in female patients following hip resurfacing.

Pedicle screws (PS) can provide initial stabilization of anterior interbody femoral ring allograft (FRA) lumbar constructs. Translaminar screws (TLS) have also been ad- vocated for this procedure. The objective of this study was to use an in vitro human cadaveric model to compare the stability of one-level anterior interbody lumbar constructs stabilized with PS and those stabilized with TLS. Five human cadaveric spinal motion segments (L4-S2) were biomechani- cally evaluated in the intact condition and using the follow- ing methods of stabilization: anterior interbody fusion with FRA, anterior FRA supplemented with PS, and anterior FRA supplemented with TLS. Stability was determined for each construct by measuring construct displacement as a function of applied load under the following conditions: compression, fexion, extension, lateral bending to each side, and axial torsion. There were no statistically signifcant differences in construct stability between FRA supplemented with PS and FRA supplemented with TLS under any of the loading conditions. In selected cases, supplementation of anterior femoral ring allograft with translaminar screws is a viable alternative to supplementation with pedicle screws.

Purpose. It is somewhat surprising that radiographic criteria for lumbar stenosis have been transposed from radiography and CT to MR without scientific validation. As these radiographic criteria were developed via population studies with criteria defned by two standard deviations from the mean, we sought to perform the same methodology via MR. Methods. The study was approved by the institutional review board; the requirement for informed consent was waived. One-hundred patients referred for possible metastatic disease, aged 4 to 94 were studied. Measurements were obtained on a midline sagittal T2-weighted (6000/120) image at each disc level, as well as at the mid-vertebral level. The distributive mean, and standard deviations were calculated and -2 SD was used as a “cutoff” for spinal stenosis. To assess for interobserver variation, 20% of the measurements were repeated by a second observer. To assess for intraobserver variation, another 20% of the measurements were repeated a second time at a minimum of a two month interval. Results. The spinal canal was narrowest at L5-S1 (mean: 1.16 cm), and widest at L1-L2 (mean: 1.56 cm). Overall the narrowest measurements were at the intervertebral disc space and were narrower at the lower disc spaces. In our population, the lowest cutoff limit (two standard deviations below the mean) had a range between 0.38 cm at the L3-L4 disc space and 0.9 cm at the L1 vertebral level. Notably at the L3 level the size range was from 0.77 to 1.75 Conclusion. Traditional measurements of canal diameters may be too large when applied to soft tissue analysis on MR. We suggest using a cutoff of smaller than 0.90 cm for developmental stenosis.

Orthopaedic patients with poor nutritional status are at an increased risk of postoperative complications, such as infection and wound healing. Nasal colonization with Staphylococcus aureus, especially with methicillin-resistant Staphylococcus aureus, has been shown to be a risk factor for surgical-site infections. We examined the incidence of nutritional depletion in our arthroplasty population and its correlation with Staphylococcus aureus colonization. We conducted a retrospective review of prospectively collected data of our arthroplasty patient population. Patients with known Staphylococcus aureus colonization or surgical-site infection were compared with a random cohort of patients. Patient demographics, preoperative nasal culture, and two nutritional screening scores were collected. Six hundred and ffty-two patients underwent arthroplasty and completed preoperative nasal cultures and nutritional assessment. A high percentage (27%) of our patients demonstrated some level of nutritional depletion prior to joint replacement. Overall nutritional scores were not signifcantly associated with surgery-type, preoperative nasal culture, or surgical- site infection in our patient population.

Background. Although the effect of Staphylococcus aureus (SA) decolonization on surgical site infection (SSI) rates has been studied, patient tolerance and acceptance of these regimens has not been assessed. Surgical patients at our hospital’s Pre-Admission Testing Clinic (PAT) receive SA reduction protocols instructing the preoperative use of chlorhexidine gluconate (CHG) soap and intranasal mupiro- cin ointment (MO). Certain insurers do not cover MO costs resulting in out of pocket (OOP) expenses for some patients. Objective. This study assessed patient attitudes and compliance with our hospital’s SA decolonization regimen. Methods. One-hundred-forty-six patients received sur- veys. Descriptive statistics were used for analysis. Results. Of respondents ftting inclusion criteria, 81% followed the MO protocol (MO users) while 89% followed the CHG protocol (CHG users). Fifty-four percent of MO users reported OOP expenses and 13% reported a hard or very hard fnancial burden. Ninety-three percent of CHG users reported the protocol was easy or very easy to follow. Conclusion. Eighty-one percent of patients receiving the SA protocol were fully compliant despite cost or diffculty obtaining MO. Given these barriers and some diffculty with CHG application, we hypothesize compliance may be im- proved if MO is provided to patients without OOP expenses and if the CHG application method is simplifed.

Background. Traditional surgical treatment of isthmic spon- dylolisthesis is posterior-lateral fusion, but the addition of anterior surgery has been explored. The purpose of this study was to evaluate the surgical and clinical outcomes of anterior-posterior surgical treatment for low-grade isthmic spondylolisthesis. Methods. Retrospectively, we enrolled 23 consecutive patients (mean age of 50) who underwent surgical treatment for low grade isthmic spondylolisthesis. The mean follow-up was 10 months. Basic demographic and radiographic data was collected. Pre- and post-surgical clinical surveys (VAS, ODI, and SF-36) were collected. Results. All 23 patients underwent anterior interbody fusion with a femoral ring allograft or ICBG in combina- tion with posterior lumbar decompression and fusion with instrumentation. The average slip percentage decreased from 23.2% to 19.0% (p = 0.24) while slip angle increased from 9.8° to 17.9° (p < 0.001) and average disc height decreased from 1.9 cm to 0.80 cm (p < 0.001). VAS scores decreased from 7.1 to 2.4 (p < 0.001), ODI scores decreased from 52.5 to 28.1 (p < 0.001), and SF-36 scores increased in the Physical Component Scale (PCS) from 29.5 to 42.6 (p < 0.001). Conclusion. In our study, patients demonstrated an im- provement in the ODI as well the physical component scores of the SF-36, thus having a good clinical outcome.

Spontaneous osteonecrosis of the knee (SPONK) and osteo- necrosis in the postoperative knee (ONPK) are two clinical entities that have the potential to cause signifcant morbid- ity in affected patients. In addition to the knowledge of the patient population at risk and the classic presentation and imaging characteristics of SPONK and ONPK, the treat- ing orthopaedic surgeon needs to maintain a high index of suspicion for these disorders since early diagnosis and treatment may allow for an improved clinical outcome. The following review presents the current knowledge regarding these two pathological processes of the knee.

Alkaptonuria is a rare disease in which a defciency in the homogentisate 1, 2-dioxygenase enzyme results in a buildup of homogentisic acid. Ochronosis, the deposition of excess homogentisic acid in connective tissue, causes brownish-black pigmentation and weakening of the tissue ultimately resulting in chronic infammation, degeneration, and osteoarthritis. There is currently no defnitive cure for alkaptonuric ochronosis, and management is usually symp- tomatic. However, total joint replacements in severe cases of ochronotic osteoarthritis have comparable outcomes to osteoarthritic patients without ochronosis. We report a case of a patient with ochronotic arthritis of the knee treated with total knee arthroplasty.

Intraarticular coronal fracture of the femoral condyle is rare, and an isolated medial Hoffa fracture in a child is extremely rare. To our knowledge, such a case has not yet been reported in the literature. Early diagnosis and prompt treatment are essential for a good long-term outcome. We report a case of 12-year-old male who suffered a traffc accident and sustained an isolated medial Hoffa fracture. Open reduction was performed using a subvastus approach and the joint surface congruity restored and secured by two large fragment partially threaded screws placed from anterior to posterior in the epiphysis. At the 36-month follow-up, the fracture was united, and the patient had full extension and approximately 130° fexion of knee. There was no varus or valgus instability or limb length discrepancy. This case highlights the importance of early diagnosis and prompt treatment in the form of epiphyseal fxation for the management of these fractures in skeletally immature individuals.

The incidence of isthmic spondylolysis is approximately 3% to 6% in the general population. Spondylolytic defects involving multiple vertebral levels, on the other hand, are extremely rare. Only a handful of reports have examined the outcomes of surgical treatment of multi-level spondylolysis. Here, we present one case of bilateral pars defects at L3, L4, and L5. The patient, a 46-year-old female, presented with lower back pain radiating into the left lower extremity. Radiographs and CT scans of the lumbar spine revealed bilateral pars defects at L3-L5. The patient underwent lumbar discectomy and interbody fusion of L4-S1 as well as direct repair of the pars defect at L3. There were no postoperative complications, and by seven months the patient had improved clinically. While previous reports describe the use of either direct repair or fusion in the treatment of spondylolysis, we are unaware of reports describing the use of both techniques at adjacent levels.