Robotic-Assisted Total Knee Arthroplasty: What are Patients' Perspectives, Understanding and Expectations?

BACKGROUND

The rate of using robotic-assisted total knee arthroplasty (RA-TKA) has increased markedly. Understanding how patients view the role of robotics during total knee arthroplasty (TKA) informs shared decision making and facilitate efforts to appropriately educate patients regarding the risks and benefits of robotic assistance.

METHODS

A self-administered questionnaire was completed by 440 potential TKA patients at the time of their surgery scheduling. Participants answered 25 questions regarding RA-TKA, socioeconomic factors, and their willingness to pay (WTP) for RA-TKA. Logistic regressions were used to determine if population characteristics and surgeon preferences influenced the patients' perceptions of RA-TKA.

RESULTS

There were 39.7% of respondents who said that they had no knowledge regarding RA-TKA. Only 40.7% of participants had expressed a desire for RA-TKA to be used. There were 8.7% who were WTP extra for the use of RA-TKA. Participants believed that the main 3 benefits of RA-TKA compared to conventional methods were: more accurate implant placement (56.2%); better results (49.0%); and faster recovery (32.1%). The main 3 patient concerns were harm from malfunction (55.2%), reduced surgeon role in the procedure (48.1%), and lack of supportive research (28.3%). Surgeon preference of RA-TKA was associated with patient's willingness to have RA-TKA (odds ratio 4.60, confidence interval 2.98-7.81, P < .001), and with WTP extra for RA-TKA (odds ratio 2.05, confidence interval: 1.01-4.26, P = .049).

CONCLUSION

Patient knowledge regarding RA-TKA is limited. Nonpeer-reviewed online information may make prospective TKA candidates vulnerable to misinformation and aggressive advertising. The challenge for orthopaedic surgeons is to re-establish control and reliably educate patients about the proven advantages and disadvantages of this emerging technology.

Bibliometric Analysis of Spinopelvic Alignment in Total Hip Arthroplasty

INTRODUCTION

Postoperative dislocation of unclear etiology remains a concern after total hip arthroplasty (THA). Interest is growing in the importance of spinopelvic alignment on stability in THA. The purpose of this study was to analyze publication trends, areas of interest, and future research direction of spinopelvic alignment in THA.

METHODS

Articles on the topic of spinopelvic alignment in THA published between 1990 and 2022 were obtained through Web of Science Core Collection of Clarivate Analytics (WSCCA). Results were screened by title, abstract, and full text. The inclusion criterion was English-language peer-reviewed journal publications on the clinical topic of spinopelvic alignment in THA. Bibliometric software was used to characterize publication trends.

RESULTS

We screened 1,211 articles, yielding 132 meeting the inclusion criterion. From 1990 to 2022, published articles have steadily increased, peaking in 2021. Countries that have been the most productive in contributions to research are those in which THA is the most prevalent. Our analysis of keyword frequency showed increasing interest in "pelvic tilt," "anteversion," and "acetabular component" position.

CONCLUSION

Our study identified that increasing attention is being given to spinopelvic mobility and PT in the setting of THA. The United States and France produced the most studies related to spinopelvic alignment.

Analysis of Orthopaedic In-Training Examination Trauma Questions: 2017 to 2021

INTRODUCTION

The Orthopaedic In-Training Examination (OITE) is a multiple-choice examination developed by the American Academy of Orthopaedic Surgeons annually since 1963 to assess orthopaedic residents' knowledge. This study's purpose is to analyze the 2017 to 2021 OITE trauma questions to aid orthopaedic residents preparing for the examination.

METHODS

The 2017 to 2021 OITEs on American Academy of Orthopaedic Surgeons' ResStudy were retrospectively reviewed to identify trauma questions. Question topic, references, and images were analyzed. Two independent reviewers classified each question by taxonomy.

RESULTS

Trauma represented 16.6% (204/1,229) of OITE questions. Forty-nine percent of trauma questions included images (100/204), 87.0% (87/100) of which contained radiographs. Each question averaged 2.4 references, of which 94.9% were peer-reviewed articles and 46.8% were published within 5 years of the respective OITE. The most common taxonomic classification was T1 (46.1%), followed by T3 (37.7%) and T2 (16.2%).

DISCUSSION

Trauma represents a notable portion of the OITE. Prior OITE trauma analyses were published greater than 10 years ago. Since then, there has been an increase in questions with images and requiring higher cognitive processing. The Journal of Orthopaedic Trauma (24.7%), Journal of the American Academy of Orthopaedic Surgeons (10.1%), and Journal of Bone and Joint Surgery, American Volume (9.3%) remain the most cited sources.

Determining Radiographic Reliability of Pelvic Landmarks in Assessing Limb Length Discrepancy Following Total Hip Arthroplasty

Limb length discrepancy (LLD) is a frequent complication following total hip arthroplasty (THA) often associated with patient dissatisfaction. Radiographic landmarks are commonly used to determine limb length, but their reliability and accuracy remain to be validated. One-hundred and sixty-two preoperative standing pelvic radiographs from patients undergoing THA were measured using four common landmarks (teardrop, ischial tuberosity, obturator foramen, and iliac crest.) LLD and angular differences between measurements were obtained. Comparison of these landmarks for measuring leg lengths showed weak correlation and wide ranges of LLD for each method - in some cases differing by 30 mm. Angular comparisons showed similar results. Surgeons should be cautioned that there is no standard and reliable method for radiographic measurement of leg length in association with hip replacement surgery and use of these techniques in clinical and research settings should be approached cautiously. (Journal of Surgical Orthopaedic Advances 32(1):028-031, 2023).

A Consistent Anatomic Landmark for Identifying the Lateral Femoral Circumflex Artery in a Direct Anterior Hip Approach

A direct anterior approach (DAA) is a technique practiced by arthroplasty surgeons that can be technically challenging, most notably for inexperienced surgeons. The lateral femoral circumflex artery (LFCA) is a branch of the femoral artery that crosses the surgical field during DAA and is an important landmark for superficial surgical dissection. If the vessel is not identified, significant bleeding may occur, and visualization may be impaired. This study aimed to develop a reliable method to identify and ligate the LFCA with minimal bleeding. First, a retrospective review was performed on a series of patients who underwent primary DAA total hip arthroplasty. Epidemiologic and intraoperative radiologic information was collected to determine the 2-dimensional location of the LFCA as it coursed through the surgical interval. Second, a series of computed tomography (CT) angiograms were compared to validate the intraoperative anatomic findings. In this study, 108 patients were evaluated fluoroscopically and 100 CT angiograms were obtained, for 208 total patients. The distance of the LFCA from the lesser trochanter with standard fluoroscopy (LT/TD) was 0.600 vs 0.438 on CT angiogram. Mean offset from midline (offset/femur diameter) was 0.166 lateral to midline vs 0.36 medial to midline. Median value of offset was 0 vs 0.411-representing a position on the anatomic axis of the femur. This study confirmed that the LFCA is found approximately one-third to two-thirds of the way between the lesser and greater trochanters along the anatomic axis of the femur for most patients. Surgeons who are new to DAA can use the LFCA as a reliable landmark to confirm the correct interval. [Orthopedics. 2022;45(5):262-268.].

Intraoperative Acoustics: Auditory Cues in Hip Reconstructive Surgery

BACKGROUND

Orthopaedic surgeons rely on visual and tactile cues to guide performance in the operating room (OR). However, there is very little data on how sound changes during orthopaedic procedures and how surgeons incorporate audio feedback to guide performance. This study attempts to define meaningful changes in sound during vital aspects of total hip arthroplasty (THA) within the spectrum of human hearing.

METHODS

84 audio recordings were obtained during primary elective THA procedures during sawing of the femoral neck, reaming of the acetabulum, acetabular cup impaction, polyethylene liner impaction, femoral broaching, planning of the femoral calcar and press-fit of a porous-coated stem in 14 patients. We graphed changes in frequency intensity across the human spectrum of hearing and sampled frequencies showing differences over time for statistically meaningful changes.

RESULTS

Sawing of the femoral neck, polyethylene impaction, and stem insertion showed significant temporal increases in overall sound intensity. Calcar planing showed a significant decrease in sound intensity. Moreover, spectrographic analysis showed that, for each of the critical tasks in THA, there were characteristic frequencies that showed maximal changes in loudness. These changes were above the 1 dB change in intensity required for detection by the human ear.

CONCLUSION

Our results clearly demonstrate reproducible sound changes during total hip arthroplasty that are detectable by the human ear. Surgeons can incorporate sound as a valuable source of feedback while performing total hip arthroplasty to guide optimal performance in the OR. These findings can be extrapolated to other orthopaedic procedures that produce characteristic changes in sound. Moreover, it emphasizes the importance of limiting ambient noise in the OR that might make sound changes hard to distinguish.

Demand Matching Total Joint Replacement Patients Results in Reduction of Post-Discharge Costs

BACKGROUND

The shift from fee-for-service to value-based care has focused payers and providers on resource utilization. One important component of value-based care is to reduce the use of post-discharge (PD) services in a clinically appropriate manner following total joint arthroplasty (TJA). Demand matching in healthcare is the process of tailoring appropriate medical care to a patient with respect to that patient's specific medical needs and social determinants. Outcomes following the implementation of a demand-matching algorithm for coordinating PD services after TJA were analyzed in this study.

METHODS

Payment data from all Medicare patients undergoing primary unilateral TJA between July 2014 and December 2018 from a single orthopedic practice were included. These payments were separated into acute and PD care. The initial acute and PD costs were compared to costs at the end of the 4-year study period using multiple linear regression and chi-square.

RESULTS

A total of 9,638 patients (4,212 total hip arthroplasties and 5,430 total knee arthroplasties) were included. Acute costs of TJA were stable averaging $13,712.00. PD costs fell steadily from a baseline average of $7,319.00 in July 2014 to $4,678.00 in December 2018 (P < .001), representing a 36.1% decline. Discharge to home increased steadily from 45.8% to 79.9% during the same interval (P < .001.) CONCLUSION: Our results demonstrate a statistically significant reduction in PD costs over a 4-year period using a demand-matching strategy to align with the Centers for Medicare and Medicaid Services mandate for value-based care. Based on these data, we conclude that thoughtful preoperative assessment of patient factors such as social determinants and medical comorbidities could allow for cost reduction through better utilization of PD services.

"Uncontrolled" Hypertension Is Not an Independent Risk Factor for Adverse Short-Term Outcomes Following Total Joint Arthroplasty

BACKGROUND

Uncontrolled hypertension (HTN) is a risk factor for mortality following elective surgery and poor hemodynamic control during total joint arthroplasty (TJA). However, the relationship between uncontrolled HTN and TJA outcomes remains poorly understood. The purpose of this study is to better define HTN parameters that are predictive of adverse arthroplasty outcomes.

METHODS

This is a retrospective cohort analysis on patients who underwent primary TJA for osteoarthritis between 2017 and 2021 at a large orthopedic practice. Uncontrolled HTN was defined as a systolic blood pressure (SBP) > 140 mm Hg, or diastolic blood pressure (DBP) > 90 mm Hg. Spearman's rank correlations were used to evaluate relationships among uncontrolled HTN and operative duration, hemoglobin drop, allogenic transfusions, length of stay, intraoperative/postoperative complications, and readmissions.

RESULTS

Four thousand three hundred forty-five patients met the selection criteria, of which 55.1% (N = 2394) presented with uncontrolled HTN. In total, 17.1% (N = 745) and 3.2% (N = 138) of patients had an SBP ≥ 160 and 180 mm Hg, respectively. In addition, 1.9% of patients (N = 84) presented with SBP ≥ 200 mm Hg (N = 13) and/or DBP ≥ 100 mm Hg (N = 71). Eight-four percent (N = 626) of patients who presented with SBP > 160 mm Hg had been preoperatively prescribed HTN control medications. Receiver operator curve analysis demonstrated poor predictive value of blood pressure for all aforementioned outcome variables.

CONCLUSION

Our findings suggest that as defined, uncontrolled HTN is not an appropriate individual predictor of TJA outcomes and should not be used as a "hard stop" when determining eligibility for elective surgery. Further research utilizing a larger cohort is needed to define the relationship between HTN and TJA outcomes.

Demand Matching and Site of Care: High-Cost Facilities Do Not Improve Short-term Quality Metrics Following Total Hip and Knee Arthroplasty

With increased emphasis on improving value in total hip arthroplasty (THA) and total knee arthroplasty (TKA) care, concerns exist about whether variability in hospital costs between facilities is justified. The purpose of this study was to compare index facility reimbursement among hospitals and short-term outcomes for patients undergoing primary THA and TKA. We queried a single private insurer's claims data, identifying all patients undergoing THA or TKA from 2015 to 2017 performed by 25 surgeons across 16 hospitals within our institution. Hospitals were divided into high- and low-cost facilities based on mean index reimbursement. We compared comorbidities, episode-of-care costs, and short-term outcomes between facilities and performed multivariate analyses. Of 2963 procedures, 1305 (44%) were performed at higher-cost hospitals. Higher-cost facilities had higher mean index reimbursement ($40,597 vs $26,781, P<.0001) and higher mean Charlson Comorbidity Index (CCI; 0.32 vs 0.24, P=.0029), but no difference in complications (2.2% vs 1.8%, P=.3955) or readmissions (2.2% vs 1.5%, P=.1490). On multivariate analyses, higher-cost facility increased index reimbursement by $13,780 (95% CI, $13,489-$14,071, P<.0001) and discharge to facility risk (odds ratio [OR], 3.2; 95% CI, 1.9-5.4; P<.0001), but not complication (OR, 1.2; 95% CI, 0.7-2.0; P=.5983) or readmission (OR, 1.5; 95% CI, 0.9-2.6; P=.1474) risks. Shifting 25% of patients with a CCI of 0 from higher- to lower-cost centers would have decreased inpatient facility costs by an estimated $3,582,784. Wide variability exists between hospital facility costs for THA and TKA without differences in short-term outcomes. Demand matching healthier patients to lower-cost facilities may significantly lower the overall procedural costs of THA and TKA. [Orthopedics. 2022;45(1):19-24.].

The Frequency, Reasoning, and Impact of Repeated Radiographs at the Initial Orthopedic Arthroplasty Visit

BACKGROUND

Patients presenting to an orthopedic clinic with joint pain often seek prior care and imaging before consultation. It is unknown how often orthopedic surgeons must repeat imaging and whether repeat imaging has an impact on diagnosis or management. The purpose of this study was to determine the frequency, reason, and impact of repeating radiographs in outpatient orthopedic clinics.

METHODS

Patients ≥18 years of age presenting with hip and/or knee pain were prospectively enrolled at five arthroplasty clinics from January 2019 until June 2020. Before the initial visit, surveys were distributed to patients regarding the reason for their visit, prior care, and prior diagnostic imaging. At the conclusion of the visit, surgeons reported if repeat radiographs were obtained, and if so, surgeons documented the views ordered, the reasoning for new films, and if diagnosis or management changed as a result. Patients were grouped based on repeat imaging status, and of those with repeat imaging, subgroup analysis compared patients based on if management changed.

RESULTS

Of 292 patients, 256 (88%) had radiographs before their office visit, and 167 (65%) obtained repeat radiographs. Radiographs were most commonly repeated if they were inaccessible (47%), followed by if they were non-weight-bearing (40%). Repeated radiographs changed the diagnosis in 40% of patients and changed management in 22% of patients.

CONCLUSION

Most patients underwent repeat radiography at their orthopedic visit. The primary reasons were owing to accessibility or the patient being non-weight-bearing. Repeat radiographs changed management in almost one-quarter of patients.

The Hospital Frailty Risk Score is Not an Accurate Predictor of Treatment Costs for Total Joint Replacement Patients in a Medicare Bundled Payment Population

BACKGROUND

Medically complex patients require more resources and experience higher costs within total joint arthroplasty (TJA) bundled payment models. While risk adjustment would be beneficial for such patients, no tool currently exists which can reliably identify these patients preoperatively. The purpose of this study is to determine if the Hospital Frailty Risk Score (HFRS) is a valid predictor of high-TJA treatment costs.

METHODS

Retrospective analysis was performed on patients who underwent primary TJA between 2015 and 2020 from a single large orthopedic practice. ICD-10 codes from an institutional database were used to calculate HFRS. Cost data including inpatient, postacute, and episode of care (EOC) costs were collected. Charlson comorbidity index, demographics, readmissions, and complications were analyzed.

RESULTS

4936 patients had a calculable HFRS and those with intermediate and high scores experienced more frequent readmissions/complications after TJA, as well as higher EOC costs. However, HFRS did not reliably predict EOC costs, yielding a sensitivity of 49% and specificity of 66%. Multivariate analysis revealed that both patient age and sex are superior individual cost predictors when compared with HFRS. Secondary analyses indicated that HFRS more effectively predicts TJA complications and readmissions but is still nonideal for clinical applications.

CONCLUSION

HFRS has poor sensitivity as a predictor of high-EOC costs for TJA patients but has adequate specificity for predicting postoperative readmissions and complications. Further research is needed to develop a scale that can appropriately predict orthopedic cost outcomes.

Broach Handle Design Changes Force Distribution in the Femur During Total Hip Arthroplasty

BACKGROUND

Curved broach handles were developed to overcome limited surgical exposures during total hip arthroplasty. Some authors report increased intraoperative fracture rates during limited exposures. This study evaluates mechanical force ratios transmitted to the bone while broaching with curved vs straight handles.

METHODS

An experimental model utilized a 6-axis load cell to measure force distributions produced by 4 different broach handles, each with increasing offset and curvature. Handles were separately impacted and dynamic variables assessed. Handles were then digitized using a high-resolution optical system and a finite element analysis (FEA) was performed to account for trabecular bone and vary the location of mallet impact. Off-axis forces, broaching construct moments, and stress within surrounding bone were computed.

RESULTS

Using the experimental model, high-offset handles lost on average 4% more hammering force to the horizontal axis. When the FEA utilized moduli of elasticity to estimate broaching through osteoporotic trabecular bone, horizontally displaced forces (toward cortical bone) were magnified from 4% to a maximum value of 52%. Both the experimental construct and FEA confirmed that larger offset handles increase moment-to-force ratios up to 163%-235%, thus rotating the proximal and distal ends of the broach toward cortical bone.

CONCLUSION

Broach handle design is an important determinant of resultant forces transmitted to the broach (and ultimately the bone) during total hip arthroplasty. Unwanted off-axis forces and enhanced rotational dynamics may play a role in intraoperative fractures during femoral canal preparation.

Does Knowledge of Implant Cost Affect Fixation Method Choice in the Management of Stable Intertrochanteric Hip Fractures?

We conducted a study to determine if knowledge of implant cost affects fixation method choice in the management of stable intertrochanteric hip fractures. We retrospectively reviewed the cases of 119 patients treated with a sliding hip screw (SHS; Versafix), a short Gamma nail (SGN), or a long Gamma nail (LGN). Of the 119 fractures, 71 were treated before implant costs were revealed, and 48 afterward. The 2 groups were similar in age, sex, fracture types, American Society of Anesthesiologists physical status classification, and preinjury ambulatory status. SHS was used in 38.0% of the before cases and 27.1% of the after cases, SGN in 29.6% of the before cases and 45.8% of the after cases, and LGN in 32.4% of the before cases and 27.1% of the after cases. Changes in implant use were not statistically significant. SHS was favored for 31-A1.1, 31-A1.2, and 31-A2.1 fractures in the before group but only for 31-A1.2 fractures in the after group. Gamma nails of both sizes were preferred in the after group for 31-A1.1, 31-A1.3, and 31-A2.1 fractures. At our institution, surgeon knowledge of implant cost did not affect fixation method choice in the management of stable intertrochanteric hip fractures.

Intraoperative Fluoroscopy Improves Component Position During Anterior Hip Arthroplasty

The goal of this retrospective review was to determine whether fluoroscopic guidance improves acetabular cup abduction and anteversion alignment during anterior total hip arthroplasty. The authors retrospectively reviewed 199 patients (fluoroscopy group, 98; nonfluoroscopy group, 101) who underwent anterior total hip arthroplasty at a single center with and without C-arm fluoroscopy guidance. Included in the study were patients of any age who underwent primary anterior approach total hip arthroplasty performed by a single surgeon, with 6-month postoperative anteroposterior pelvis radiographs. Acetabular cup abduction and anteversion angles were measured and compared between groups. Mean acetabular cup abduction and anteversion angles were 43.4° (range, 26.0°-57.4°) and 23.1° (range, 17°-28°), respectively, in the fluoroscopy group. Mean abduction and anteversion angles were 45.9° (range, 29.7°-61.3°) and 23.1° (range, 17°-28°), respectively, after anterior total hip arthroplasty without the use of C-arm guidance (nonfluoroscopy group). The use of fluoroscopy was associated with a statistically significant difference in cup abduction (P=.002) but no statistically significant difference in anteversion angles. In the fluoroscopy group, 80% of implants were within the combined safe zone compared with 63% in the nonfluoroscopy group. A significantly higher percentage of both acetabular cup abduction angles and combined anteversion and abduction angles were in the safe zone in the fluoroscopy group. Fluoroscopy is not required for proper anteversion placement of acetabular components, but it may increase ideal safe zone placement of components.

Metastatic cystosarcoma phyllodes associated with paraplegia: an uncommon complication of an uncommon tumor

Cystosarcoma phyllodes is a rare form of breast cancer that rarely metastasizes. This case represents the first reported case of a pathological spine fracture and neurologic injury as a result of metastatic cystosarcoma phyllodes. Physicians should be aware of a recently identified histological subtype of cystosarcoma that exhibits an increased incidence of hematogenous metastasis.

Diagnosis and management of the infected total joint arthroplasty

The preoperative diagnosis of the infected orthopedic implant is complicated by lack of a single precise test to forewarn patient and surgeon of the presence of microorganisms. Given the overall limitation of accuracy of preoperative diagnosis to approximately 80% when 111In scanning, preoperative aspiration, and ESR are considered, it would seem prudent to approach each revision surgery with the possibility in mind of subclinical sepsis as the cause for failure of the implant. The essentials of surgical technique including thorough debridement of the wound and removal of all existing foreign bodies, especially including PMMA bone cement, are critical to minimizing the risk for occurrence or persistence of sepsis. Although the use of antibiotic impregnated bone cement may enhance the treatment of orthopedic sepsis, the data available to date lead to the conclusion that two-stage revision surgery in the face of known sepsis remains the cornerstone of surgical therapy for the infected implant, along with aggressive and rational antibiotic treatment. The surgeon is offered the following guidelines in the management of the septic total hip arthroplasty. 1. Preoperative evaluation including ESR, 111In WBC scan, and aspiration for culture and sensitivity (fluoroscopically guided for the hip) will produce on average approximately 80% accuracy. 2. Intraoperative cultures at the time of revision surgery should be obtained prior to administration of systemic antibiotics; three tissue specimens (hip capsule, femoral membrane, acetabular membrane) should be submitted for culture and sensitivity determination. 3. Careful debridement of the surgical site of granulation tissue and all foreign bodies (e.g., PMMA) should be performed within the limits of patient safety to maximize the likelihood of success.(ABSTRACT TRUNCATED AT 250 WORDS)

Immediate closed reduction of cervical spine dislocations using traction

Cervical facet dislocations may be reduced rapidly and effectively using axial traction with weights applied at over the traditional 45-pound limit. Fifty-three sequential patients with cervical facet dislocations were reviewed. Thirty-nine patients required more than 50 pounds of traction to achieve rapid reduction. Sixty-eight percent of the entire series showed significant improvement in neurologic function. There were no cases of significant loss of function. A cadaver study confirmed that the cranial tongs could support over 100 pounds of traction. Careful application of up to 100 pounds seems to be associated with a low risk of neurologic compromise or tong failure, but results in effective reduction of dislocations.

Difficulties during removal of fluted femoral intramedullary rods

The difficulties that were encountered during removal of a fluted intramedullary femoral rod from six patients were reviewed. The mechanisms of failure included metal breakage at three different locations along the rod or the rod extractor. Three of the six rods were left in place due to difficulties in removal. The design of the fluted intramedullary rod appears to be the main cause of the problem.

Capacitively coupled electrical stimulation of bovine growth plate chondrocytes grown in pellet form

Pellets formed from isolated bovine growth plate chondrocytes were grown in various capacitively coupled electrical fields. The signals chosen were 0, 10, 100, 250, 500, 750, 1,000, and 1,500 V peak-to-peak, 60 kHz. The effect on cell proliferation and matrix production of these different voltages was determined by [3H]thymidine and [35S]sulfate uptake, respectively, Cyclic AMP assays were done to determine if increases in either thymidine or sulfate uptake were associated with changes in cAMP levels. Significantly increased cell proliferation occurred at 500, 750, and 1,000 V peak to peak. The calculated electric fields were 1.5 to 3.0 x 10(-2) V/cm. Proliferation was significantly inhibited at 1,500 V peak-to-peak with a calculated field of 4.5 x 10(-2) V/cm. Little if any change was seen in cAMP levels at 30 or 60 min following application of the appropriate electric signals.

Cytosolic calcium concentration in bovine growth plate chondrocytes

The cytosolic free calcium ion concentration for mammalian cell systems is believed to be maintained within a narrow range compatible with cellular homeostasis. Growth plate chondrocytes have been shown to accumulate large quantities of calcium within their mitochondria, but the cytosolic free calcium concentration has not been determined. This study measures the cytosolic free ionic calcium concentration in growth plate chondrocytes using two variations of the Quin II fluorescence technique. The results indicate that in isolated growth plate chondrocytes, the cytosolic free ionic calcium concentration is similar to other nonmineralizing mammalian cell types (106-137 mM).