Cervical disc arthroplasty versus anterior cervical discectomy and fusion: an analysis of the Michigan Spine Surgery Improvement Collaborative Database

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) are established surgical options for the treatment of cervical radiculopathy, myelopathy, and cervical degenerative disc disease. However, current literature does not demonstrate a clear superiority between ACDF and CDA.

PURPOSE

To investigate procedural and patient-reported outcomes of ACDF and CDA among patients included in the Michigan Spine Surgery Improvement Collaborative (MSSIC) database.

DESIGN

Retrospective study of prospectively collected outcomes registry data.

PATIENT SAMPLE

Individuals within the MSSIC database presenting with radiculopathy, myelopathy, or cervical spondylosis refractory to typical conservative care undergoing primary ACDF or CDA from January 4, 2016, to November 5, 2021.

OUTCOME MEASURES

Perioperative measures (including surgery length, length of stay, return to OR, any complications), patient-reported functional outcomes at 2-year follow-up (including return to work, patient satisfaction, PROMIS, EQ-5D, mJOA).

METHODS

Patients undergoing ACDF were matched 4:1 with those undergoing CDA; propensity analysis performed on operative levels (1- and 2- level procedures), presenting condition, demographics, and comorbidities. Initial comparisons performed with univariate testing and multivariate analysis performed with Poisson generalized estimating equation models clustering on hospital.

RESULTS

A total of 2,208 patients with ACDF and 552 patients with CDA were included. Baseline demographics were similar, with younger patients undergoing CDA (45.6 vs 48.6 years; p<.001). Myelopathy was more frequent in ACDF patients (30% vs 25%; p=.015). CDA was more frequently planned as an outpatient procedure. Length of stay was increased in ACDF (1.3 vs 1.0 days; p<.001). Functional outcomes were similar, with comparable proportions of patients meeting minimal clinically important difference thresholds in neck pain, arm pain, PROMIS, EQ-5D, and mJOA score. After multivariate regression, no significant differences were seen in surgical or functional outcomes.

CONCLUSIONS

This study demonstrates similar outcomes for those undergoing ACDF and CDA at 2 years. Previous meta-analyses of CDA clinical trial data adhere to strict inclusion and exclusion criteria required by clinical studies; this registry data provides "real world" clinical outcomes reflecting current practices for ACDF and CDA patient selection.

Radiographic Fusion Outcomes for Trinity Cellular Based Allograft versus Local Bone in Posterolateral Lumbar Fusion

INTRODUCTION

Cellular-based autograft (CBA) is being used in posterolateral lumbar arthrodesis as a fusion supplementation alternative.

OBJECTIVE

To assess radiographic fusion in patients undergoing posterolateral lumbar fusion with unilateral Trinity CBA compared with contralateral local bone autograft as an internal control.

METHODS

A single surgeon's practice database was interrogated for consecutive patients undergoing primary posterolateral lumbar fusion with Trinity from 2018 to 2021. Patients had Trinity applied unilaterally, with local bone autograft applied contralaterally. Fusion was assessed postoperatively by using CT after 9 months. Demographics and patient-reported outcome measures were collected preoperatively and up to 12 months postoperatively.

RESULTS

Thirty-nine patients were included. There were 81 attempted fusion levels. Overall fusion rate, defined as bony bridging on at least one side of a given level for all levels fused, was 85.2% of patients. No statistically significant difference was observed in fusion rates between CBA versus local bone (79.0% versus 76.54% of levels attempted, respectively, P = 0.3527). Oswestry Disability Index improved by 3 months (P = 0.0152) and was maintained. Two patients required revision for symptomatic nonunion.

CONCLUSIONS

Similar radiographic fusion rates were achieved with Trinity and local bone. Trinity is a viable alternative to local bone in posterolateral lumbar fusion.

Anterior Cervical Discectomy and Fusions Supplemented With Cellular or Noncellular Allografts Have Similar Radiographic Fusion and Clinical Outcomes

STUDY DESIGN

A retrospective, single-center study.

OBJECTIVE

The aim of this study was to assess radiographic fusion after anterior cervical discectomy and fusion (ACDF) supplemented with either demineralized bone matrix or ViviGen in a polyetheretherketone biomechanical interbody cage.

SUMMARY OF BACKGROUND DATA

Cellular and noncellular allografts are utilized as adjuncts in attempts to improve fusion after ACDF. The purpose of this study was to assess radiographic fusion and clinical outcomes after ACDF supplemented with cellular or noncellular allografts.

MATERIALS AND METHODS

A single surgeon's clinical practice database was interrogated for consecutive patients who underwent a primary ACDF using cellular or noncellular allograft from 2017 to 2019. These subjects were matched by age, sex, body mass index, smoking status, and levels operated. Patient demographic and preoperative and postoperative patient-reported outcome measures (PROMs) including Visual Analog Scale Pain, Neck Disability Index, EuroQol-5 Dimension (EQ-5D), Patient-Reported Outcomes Measurement Information System (PROMIS), and Eating Assessment Tool 10 were collected preoperatively and at 3, 6, and 12 months postoperatively. Radiographic evidence of fusion was determined by <2 mm motion between spinous processes on flexion and extension radiographs and assessing bony bridging at 3, 6, and 12 months postoperatively.

RESULTS

There were 68 total patients, with 34 patients in each group, and 69 and 67 operative levels in the cellular and noncellular allograft groups, respectively. There was no difference in age, sex, body mass index, or smoking status between groups ( P >0.05). There was no difference in number of 1-level, 2-level, 3-level, or 4-level ACDFs between cellular and noncellular groups ( P >0.05). At 3, 6, and 12 months postoperatively, there was no difference in the percent of operated levels with <2 mm motion between spinous processes, complete bony bridging, or both <2 mm motion and complete bony bridging in the cellular and noncellular groups ( P >0.05). There was no difference in the number of patients fused at all operated levels at 3, 6, or 12 months postoperatively ( P >0.05). No patient required revision ACDF for symptomatic pseudarthrosis. There was no significant difference in PROMs between the cellular and noncellular groups at 12 months postoperatively except for improved EQ-5D and PROMIS-physical in the cellular compared with noncellular group ( P =0.03).

CONCLUSIONS

Similar radiographic fusion rates were achieved with cellular and noncellular allografts at all operated levels with similar PROMs in the cellular and noncellular groups at 3, 6, and 12 months postoperatively. Thus, ACDFs supplemented with cellular allograft demonstrate adequate radiographic fusion rates when compared with noncellular allografts with similar patient outcomes.

LEVEL OF EVIDENCE

Level III.

The Duration of Symptoms Influences Outcomes After Lumbar Microdiscectomies: A Michigan Spine Surgery Improvement Collaborative

STUDY DESIGN

Retrospective Cohort.

OBJECTIVE

We investigate whether duration of symptoms a patient experiences prior to lumbar microdiscectomy affects pain, lifestyle, and return to work metrics after surgery.

METHODS

A retrospective review of patients with a diagnosis of lumbar radiculopathy undergoing microdiscectomy was conducted using a statewide registry. Patients were grouped based on self-reported duration of symptoms prior to surgical intervention (Group 1: symptoms less than 3 months; Group 2: symptoms between 3 months and 1 year; and Group 3: symptoms greater than 1 year). Radicular pain scores, PROMIS PF Physical Function measure (PROMIS PF), EQ-5D scores, and return to work rates at 90 days, 1 year, and 2 years after surgery were compared using univariate and multivariate analysis.

RESULTS

There were 2408 patients who underwent microdiscectomy for lumbar disc herniation for radiculopathy with 532, 910, and 955 in Groups 1, 2, and 3, respectively. Postoperative leg pain was lower for Group 1 at 90 days, 1 year, and 2 years compared to Groups 2 and 3 (P < .05). Postoperative PROMIS PF and EQ-5D scores were higher for Group 1 at 90 days, 1 year, and 2 years compared to Groups 2 and 3 (P < .05).

CONCLUSION

Patients with prolonged symptoms prior to surgical intervention experience smaller improvements in postoperative leg pain, PROMIS PF, and EQ-5D than those who undergo surgery earlier. Patients undergoing surgery within 3 months of symptom onset have the highest rates of return to work at 1 year after surgery.

Unilateral Biportal Endoscopy for Lumbar Spinal Stenosis and Lumbar Disc Herniation

Background

Unilateral biportal endoscopy (UBE) is a novel minimally invasive technique for the treatment of lumbar spinal stenosis and lumbar disc herniations. Uniportal endoscopy was utilized prior to the advent of UBE and has been considered the workhorse of endoscopic spine surgery (ESS) for lumbar discectomy and decompressive laminectomy. However, there are theoretical advantages to UBE compared with traditional uniportal endoscopy, including that the procedure utilizes typical spinal equipment that should be readily available, requires less capital cost and optical instrumentation, and provides greater operative flexibility as a result of utilizing both a working and a viewing portal7,8.

Description

A 0-degree arthroscope is typically utilized for discectomy and lumbar laminectomies. The use of a radiofrequency ablator is critical to help coagulate osseous and muscle bleeders. For irrigation, gravity or a low-pressure pump, typically <40 mm Hg, can be utilized9,10. Further details regarding irrigation pressure are provided in "Important Tips." The use of a standard powered burr is typical to help osseous decompression, and Kerrison ronguers, pituitaries, osteotomes, and probes utilized in open or tubular cases suffice. Two incisions are made approximately 1 cm lateral to the midline. If working from the left side for a right-handed surgeon, the working portal is typically made at the lower laminar margin of the target level. The camera portal is then made typically 2 to 3 cm cephalad. A lateral radiograph is then utilized to confirm the portal placements. From the right side, the working portal is cephalad and the camera portal is caudal. Because of the switch, the portals may be shifted more distally.The first step is creating a working space because there is no true joint space in the spine. With use of radiofrequency ablation, a working space is created in the interlaminar space. Next, with use of a powered burr or a chiseled osteotomy, the base of the cephalad spinous process is thinned until the insertion of the ligamentum flavum is found. Next, the ipsilateral and contralateral laminae are thinned in a similar fashion. Once the osseous elements are removed, the ligamentum flavum is removed en bloc. The traversing nerve roots are checked under direct high-magnification visualization to ensure that they are decompressed. If a discectomy is necessary, standard nerve-root retractors can be utilized to retract the neural elements. With use of a blunt-tip elevator, the anular defect can be incised and the herniated disc can be removed under direct high-power visualization. In addition, a small curet can be utilized to create a defect in the weakened anulus or membrane covering the extruded disc material in order to help deliver the herniated disc material. Epidural veins are coagulated typically with use of a fine-point bipolar radiofrequency device.

Alternatives

Nonoperative treatments include oral anti-inflammatory drugs, physical therapy, and epidural injections; if these fail, alternative surgical treatments include open lumbar laminectomy and/or discectomy, tubular lumbar laminectomy and/or discectomy, and other minimally invasive techniques, such as microendoscopy, uniportal endoscopy, and microscopy-assisted decompression.

Rationale

UBE is a minimally invasive surgical procedure that better preserves osseous and muscular structure compared with open and tubular techniques. Conventional lumbar laminectomy involves dissection and retraction of the multifidus muscle from the spinous process to the facet joint. This exposure can damage the delicate posterior dorsal rami. Long retraction time can also lead to pressure-induced muscle atrophy and potentially increased chronic low back pain. Alternatively, smaller incisions and shorter hospital stays are possible with UBE.Similar to UBE, tubular surgery can minimize soft-tissue damage compared with open techniques; however, in a randomized trial assessing techniques for spinal stenosis surgery, Kang et al. found that UBE and tubular surgery had similarly favorable clinical outcomes at 6 months postoperatively but UBE resulted in decreased operative time, drain output, opiate use, and length of hospital stay5.Furthermore, the use of an endoscope in the biportal technique allows ultra-high magnification of the spinal pathology, decreased capital costs, and the ability to use 2 hands with freedom of movement. UBE provides clear visualization of the neural elements while keeping maximal ergonomic efficiency with the surgeon's head looking straight forward, the shoulders relaxed, and the elbows bent to 90°. Continuous irrigation through the endoscope also helps with bleeding and decreasing the risk of infection.

Expected Outcomes

Long-term outcomes do not differ substantially between discectomies performed with use of the presently described technique and procedures done with more traditional minimally invasive (i.e., tubular) techniques; however, visual analogue scale scores for back pain may be better in the short term, and there is evidence of a shorter hospital stay with UBE2. Complication rates did not differ from other minimally invasive techniques. When comparing UBE and stenosis, Aygun and Abdulshafi found that UBE was associated with decreased hospital stays, operative time, and blood loss and better clinical outcomes up to 2 years postoperatively compared with tubular laminectomy12.

Important Tips

The optimal hydrostatic pressure is 30 to 50 mm Hg. Pressure is determined by the distance between the fluid source and the working space. Because the working space does not change, the height of the bag decides pressure. A simple formula for pressure is calculated by dividing the distance from the working field to the irrigation source by 1.36. A rule of thumb is that if the bag is 50 to 70 cm above the patient's back, the pressure should be adequate. The advantages of using gravity rather than a pressure pump are that excessive fluid solution pressure in the epidural space can cause neurological issues such as nuchal pain, headache, and seizure11. Additionally, if the intertransverse membrane or the lateral margins of the disc are violated, hydroperitoneum can occur unknowingly due to the high-pressure system.Gravity or pump pressure of >40 mm Hg may elevate epidural pressure and mask operative bleeding. When the pump is turned off at the end of the surgical procedure, a postoperative epidural hematoma may occur because the bleeding source may not have been recognized while the pump pressure was on.Excessive pump pressure may lead to an increase in intracranial pressure, causing headache or delayed recovery from general anesthesia with stiff posture and hyperventilation.Make sure fluid is emerging from the working portal and the muscle area is not swelling to prevent soft-tissue fluid extravasation.Epidural veins are coagulated typically with a fine-point bipolar radiofrequency device.Osseous bleeding can be controlled with bone wax or a high-speed burr.

Acronyms and Abbreviations

MRI = magnetic resonance imagingRF = radiofrequencyAP = anteroposterior.

The Potential Negative Effects of Smoking on Cervical and Lumbar Surgery Beyond Pseudarthrosis: A Michigan Spine Surgery Improvement Collaborative Study

OBJECTIVE

To review the Michigan Spine Surgery Improvement Collaborative registry to investigate the long-term associations between current smoking status and outcomes after elective cervical and lumbar spine surgery.

METHODS

Using the Michigan Spine Surgery Improvement Collaborative, we captured all cases from January 1, 2017, to November 21, 2020, with outcomes data available; 19,251 lumbar cases and 7936 cervical cases were included. Multivariate regression analyses were performed to assess the relationship of smoking with the clinical outcomes.

RESULTS

Current smoking status was associated with lower urinary retention and satisfaction for patients after lumbar surgery and was associated with less likelihood of achieving minimal clinically important difference in primary outcome measures including Patient-Reported Outcomes Measurement Information System, back pain, leg pain, and EuroQol-5D at 90 days and 1 year after surgery. Current smokers were also less likely to return to work at 90 days and 1 year after surgery. Among patients who underwent cervical surgery, current smokers were less likely to have urinary retention and dysphagia postoperatively. They were less likely to be satisfied with the surgery outcome at 1 year. Current smoking was associated with lower likelihood of achieving minimal clinically important difference in Patient-Reported Outcomes Measurement Information System, neck pain, arm pain, and EuroQol-5D at various time points. There was no difference in return-to-work status.

CONCLUSIONS

Our analysis suggests that smoking is negatively associated with functional improvement, patient satisfaction, and return-to-work after elective spine surgery.

Endoscopic Spine Surgery: Advertisement or Game Changer?

Endoscopic spine surgery is a rapidly developing technique. Initially used for diskectomies, endoscopic spine surgery is now considered for bony decompressions and fusions. Endoscopic spine surgery uses one or two small incisions so a camera can be inserted for visualization under high magnification while a working window is provided through the camera apparatus or through a separate incision. The suggested benefits of endoscopic spine surgery include less muscle trauma, decreased need for anesthesia, reduced blood loss, and faster recovery. The typical complications associated with spinal surgery such as bleeding, infection, nerve injury, and durotomy still exist. Although the disadvantages may have historical claims, recent literature suggests endoscopic spine surgery may outperform traditional techniques for certain pathologies. However, the learning curve of endoscopic spine surgery may present challenges with adoption by practicing spinal surgeons. The outcomes of appropriately applied endoscopic techniques provide support that endoscopic spine surgery has the potential to revolutionize spine surgery.

Expandable vs Static Interbody Devices for Lateral Lumbar Interbody Fusion

Lateral lumbar interbody fusion (LLIF) has paved a way for minimally invasive surgical treatment of a wide variety of spine pathologies. Interbody devices are used to stabilize painful disc levels, provide indirect decompression of neural elements, correct deformity, restore lordosis, and provide a sound durable fusion. Through the years, new static and expandable interbody devices have been developed in an attempt to improve radiographic and clinical outcomes in lumbar spine surgery. The purpose of this article is to explore the advantages and disadvantages between static and expandable interbody devices when used in LLIF. Specifically, this article addresses the differences in subsidence, indirect decompression, restoration of lumbar lordosis, complications, patient-reported outcomes, and cost between static and expandable interbody devices.

Pediatric Upper Cervical Spine Trauma: A 10-Year Retrospective Review at a Pediatric Trauma Center

Background

Traumatic upper cervical spine injuries (tUCSI) are generally caused by high-impact injuries to the C1-C2 vertebral level. The current literature is limited with regards to comparing epidemiological trends, treatment options, and overall outcomes for tUCSI within the pediatric cohort. The purpose of this study was to analyze pediatric tUCSI epidemiological data, potential variations in treatment and patient outcomes, and to evaluate any specific trends that may be clinically relevant.

Methodology

We conducted a retrospective cohort study on pediatric patients ages 1 day to 16 years old, admitted for tUCSI over the past 10 years (1/2011 to 1/2021) at a Midwest level 1 trauma center. Retrospective data was queried using ICD-9 and ICD-10 diagnosis codes for tUCSI. Children were stratified into three age groups: Group 1 - Infants and Toddlers (children under three years of age); Group 2 - Young Children (children between three and seven years of age); Group 3 - Juveniles and Adolescents (children between the ages of seven and 16). Numerical data and categorical variables were summarized and the normality of the distribution of data was evaluated using the Anderson-Darling normality test. Differences between the age groups were examined using either an unpaired, independent Two-Sample t-test or Unpaired Mann-Whitney U test. Pearson’s chi-squared or Fisher’s exact tests were used to compare categorical data between groups.

Results

Forty total patients were included in the final analysis, 23 female (57.5%) and 17 male (42.5%). The mean age was 11 ± 4 (range 2-16). Overall, the most common mechanism of injury was a motor vehicle collision (n=16, 40%), followed by sports injury (n=13, 32.5%), falls (n=6, 15%), and unknown mechanism (n=5, 12.5%). The most common mechanism of injury in young children was a fall (n=4, 57.5%, p<0.001). Adolescents and Juveniles significantly suffer from sports injuries compared to young children (n=13, 39.4%, p=0.043). Mechanisms of injuries presented with unique associated concomitant injuries. The most common associated sites of injuries were lower cervical spine (n=31, 77.5%), and skull injury (n=4, 10%). The vast majority of these cases were managed nonoperatively (pain medication and non-operative cervical orthosis) (n=36, 90%). Mortality and morbidity rates from tUCSI were rare in our cohort (n=1, 2.5%).

Conclusion

This study found that the majority of pediatric tUCSI patients can be managed nonoperatively, with dislocations and spinal instability being the most common indications for operative management. Commonly used non-operative external fixation methods include cervical collars and Minerva jackets. Our cohort showed very low mortality and morbidity rates, however, these preliminary results will require validation by future prospective multicenter studies.

Dysphagia Weakly Correlates With Other Patient-Reported Outcomes After Anterior Cervical Discectomy and Fusion

Introduction

Dysphagia is a common complication after anterior cervical discectomy and fusion (ACDF), but it is not a routinely asked question in legacy patient-reported outcome measures (PROMs). This study analyzes whether there are associations between dysphagia and legacy outcome measures.

Methods

We retrospectively reviewed 168 patients who underwent ACDF surgery from 2017 to 2019 at a single institution. Demographics, anthropometric data, Neck Disability Index (NDI), Visual Analog Scale (VAS)-Arm and VAS-Neck Pain scores, Patient-Reported Outcomes Measurement Information System (PROMIS)-Physical and PROMIS-Mental scores, Charlson Comorbidity Index (CCI), and Eating Assessment Tool-10 (EAT-10) were obtained for each patient preoperatively and at one, three, six, and 12 months postoperatively. Pearson’s correlation coefficients were used to evaluate the bivariate correlations between legacy, PROMIS, and EAT-10 measures.

Results

Significant but weak correlations existed between NDI and EAT-10 at one, three, and six months postoperatively (correlation coefficient (R) = 0.31, 0.42, and 0.34 at one, three, and six months, p < 0.001) and VAS-Neck Pain and EAT-10 scores at one, three, and six months postoperatively (R = 0.27, 0.30, and 0.28 at one, three, and six months, p ≤ 0.004). Both PROMIS-Physical and PROMIS-Mental scores showed significant but weak correlations with EAT-10 scores at three and six months postoperatively (R = -0.29 and -0.25, p ≤ 0.01, at three months and R = -0.25 and -0.28, p < 0.01, at six months). In all comparisons of EAT-10 scores with legacy outcome measures, the significance of correlations disappeared by 12 months postoperatively. In addition, there was a positive association between CCI and EAT-10 score (β = 0.37, p < 0.05).

Conclusion

Weak correlations exist between self-reported dysphagia scores and legacy patient-reported outcome measures in patients undergoing ACDF. The correlation strength decreases over time; therefore, dysphagia scores should be reported separately when looking at outcomes after ACDF. Patients with more comorbidities are also at increased risk for dysphagia.

Does quality of life influence retear rate following arthroscopic rotator cuff repair?

BACKGROUND

The primary objective was to assess whether a patient's early postoperative quality of life (QOL) correlates with the retear rate following single-tendon double-row rotator cuff repair.

METHODS

We performed a secondary analysis of a randomized clinical trial of 58 patients who underwent single-tendon arthroscopic rotator cuff repair of full-thickness tears performed by a single surgeon. Patients were randomized to an early- or delayed-motion protocol. At 6 months, all patients underwent magnetic resonance imaging to assess whether the rotator cuffs were intact or retorn. QOL was assessed preoperatively and at 3 weeks, 6 weeks, 12 weeks, 6 months, and 12 months postoperatively using the Western Ontario Rotator Cuff (WORC) index.

RESULTS

After 6 months of rehabilitation, 41 patients (71%) had intact rotator cuff repairs whereas 17 (29%) had full-thickness tears. Patients with torn rotator cuffs at 6 months postoperatively had significantly lower WORC scores at 6 weeks postoperatively (P = .041). Patients with greater improvements in QOL perioperatively (preoperative WORC score minus 6-week postoperative WORC score > 264.5) were more likely to have full-thickness tears by 6 months postoperatively. Compliant patients assigned to the delayed-motion protocol had a failure rate of 11% (2 of 19) compared with 38% (15 of 39) in the noncompliant and early-motion protocol patients (P < .01). Overall, patients who were noncompliant with the shoulder immobilizer were 8.2 times more likely to have a failed repair on magnetic resonance imaging (P = .01).

CONCLUSIONS

Patients with better QOL shortly after arthroscopic rotator cuff repair were more likely to have retears by 6 months.

Human Subacromial Bursal Cells Display Superior Engraftment Versus Bone Marrow Stromal Cells in Murine Tendon Repair

BACKGROUND

Bone marrow aspirate is a primary source for cell-based therapies with increasing value in the world of orthopaedic surgery, especially in revision cases of tendon and ligament repairs. However, cells within peritendinous structures, such as the paratenon and surrounding bursa, contribute to the native tendon-healing response and offer promising cell populations for cell-based repair strategies. Therefore, the purpose of this study is to investigate the efficacy of cells derived from human subacromial bursa as compared with the current gold standard, bone marrow stromal cells (BMSCs), for tendon repairs in an established in vivo immunodeficient murine patellar tendon defect model.

HYPOTHESIS

Subacromial bursal cells will show superior survival and engraftment into the host tissue as compared with BMSCs.

STUDY DESIGN

Controlled laboratory study.

METHODS

Human subacromial bursal and bone marrow aspirate were harvested from the same donor undergoing rotator cuff repair. Cells were transfected with a fluorescent lentiviral vector to permanently label the cells, encapsulated into fibrin gel, and implanted into bilateral full-length central-width patellar tendon defects of immunodeficient mice. Additional surgery was performed on control mice comparing fibrin without cells and natural healing. At the time of sacrifice, all limbs were scanned on a multiphoton microscope to monitor the engraftment of the human donor cells. Afterward, limbs were assigned to either immunohistochemical or biomechanical analysis.

RESULTS

As compared with BMSCs, implanted subacromial bursal cells displayed superior tissue engraftment and survival. The main healing response in this defect model was the creation of new healing tissue over the anterior surface of the defect space. The implantation of cells significantly increased the thickness of the anterior healing tissue as compared with control limbs that did not receive cells. Cell proliferation was also increased in limbs that received implanted cells, suggesting that the donor cells stimulated a more robust healing response. Finally, these changes in the healing response did not lead to significant changes in mechanical properties.

CONCLUSION

The subacromial bursa, while often removed during rotator cuff repair, may harbor a more suitable cell source for tendon repair than BMSCs, as bursal cells display superior engraftment and survival in tendon tissue. In addition, the subacromial bursa may be a more accessible cell source than bone marrow aspirate.

CLINICAL RELEVANCE

The subacromial bursa contains a cell population that responds to tendon injury and may provide a more optimal cell source for tendon repair and regeneration strategies. Therefore, cells could be harvested from this tissue in the future, as opposed to the current practice of bursectomy and debridement.

Derotational Osteotomy of the Distal Femur for the Treatment of Patellofemoral Instability Simultaneously Leads to the Correction of Frontal Alignment: A Laboratory Cadaveric Study

Background:

Derotational osteotomy of the distal femur allows the anatomic treatment of patellofemoral maltracking due to increased femoral antetorsion. However, such rotational osteotomy procedures have a high potential of intended/unintended changes of frontal alignment.

Purpose/Hypothesis:

The purpose of this study was to perform derotational osteotomy of the distal femur and to demonstrate the utility of a novel trigonometric approach to address 3-dimensional (3D) changes on 2-dimensional imaging (axial computed tomography [CT] and frontal-plane radiography). The hypothesis was that 1-step single-cut osteotomy can simultaneously correct torsion and frontal alignment based on preoperatively calculated cutting angles.

Study Design:

Controlled laboratory study.

Methods:

Eight human cadaveric whole legs (4 lower limb torsos) underwent derotational osteotomy of the distal femur of 20°. A straight leg axis, determined as a mechanical femorotibial angle (mFTA) of 0°, was chosen as a goal for postoperative frontal alignment. The inclination of the cutting angle from the lateral view was calculated individually for each cadaveric leg and was represented by a simple 3D-printed cutting guide for surgery. Specimens underwent CT for the measurement of torsion, while the frontal leg axis was determined on an upright radiograph preoperatively and postoperatively. Preoperative and postoperative angles were compared with the mathematical prediction model.

Results:

The preoperative mFTA ranged from –3.9° (valgus) to +3.4° (varus) (mean, –0.2° ± 2.6°). A postoperative mean mFTA of 0.37° ± 0.69° (95% CI, –0.22° to 0.95°) was achieved (P = .01). Derotation showed a mean of 19.1° ± 2.1° (95% CI, 17.3°-20.8°). The oblique cutting plane for the correction of valgus legs showed a mean of 5.9° ± 6.8° and, for the correction of varus legs, a mean of –10.0° ± 4.5° projected on the perpendicular plane to the virtual anatomic shaft axis from the sagittal view.

Conclusion:

Single-cut distal femoral osteotomy can be performed to simultaneously address rotational as well as frontal alignment using a preoperatively defined oblique cut, as determined by the presented reproducible calculation model.

Clinical Relevance:

This study adds important knowledge to the technique of derotational osteotomy. This approach provides an individual, oblique single cut for the correction of torsion and frontal axis within a clinically insignificant margin. Simplified tables for calculation and a surgical reference make this model reproducible and safe.

How to avoid unintended valgus alignment in distal femoral derotational osteotomy for treatment of femoral torsional malalignment - a concept study

Background

Defining the optimal cutting plane for derotational osteotomy at the distal femur for correction of torsion in cases of patellofemoral instability is still challenging. This preliminary study investigates changes of frontal alignment by a simplified trigonometrical model and demonstrates a surgical guidance technique with the use of femur cadavers. The hypothesis was that regardless of midshaft bowing, a cutting plane perpendicular to the virtual anatomic shaft axis avoids unintended valgus malalignment due to derotation.

Methods

A novel mathematical model, called the Pillar-Crane-Model, was developed to forecast changes on frontal alignment of the femur when a perpendicular cutting plane to the virtual anatomical shaft was chosen. As proof of concept, eight different torsion angles were assessed on two human cadaver femora (left and right). A single cut distal femoral osteotomy perpendicular to the virtual anatomical shaft was performed. Frontal plane alignment (mLDFA, aLDFA, AMA) was radiographically analyzed before and after rotation by 0°, 10°, 20°, and 30°. Measurements were compared to the model.

Results

The trigonometrical equation from the Pillar-Crane-Model provides mathematical proof that slight changes into varus occur, seen by an increase in AMA and mLDFA, when the cutting plane is perpendicular to the virtual anatomical shaft axis. A table with standardized values is provided. Exemplarily, the specimens showed a mean increase of AMA from 4.8° to 6.3° and mLDFA from 85.2° to 86.7 after derotation by 30°. Throughout the derotation procedure, aLDFA remained at 80.4° ± 0.4°SD.

Conclusions

With the use of this model for surgical guidance and anatomic reference, unintended valgus changes on frontal malalignment can be avoided. When the cutting plane is considered to be perpendicular to the virtual anatomical shaft from a frontal and lateral view, a slight increase of mLDFA results when a derotational osteotomy of the distal femur is performed.

Predicting a Response to Antibiotics in Patients with the Irritable Bowel Syndrome

BACKGROUND

Antibiotics for presumed small intestinal bacterial overgrowth have been shown to improve irritable bowel syndrome symptoms in at least 40% of subjects. A lactulose breath test for small intestinal bacterial overgrowth has been used to select patients who will respond. However, its predictive value, using the classic definition of a positive lactulose breath test, has been disappointing.

AIMS

We conducted a retrospective evaluation to study characteristics of the lactulose breath test that may be predictive of a response to antibiotics in patients with the irritable bowel syndrome.

METHODS

A clinical practice database was interrogated for consecutive patients who had a lactulose breath test for irritable bowel syndrome symptoms and a subsequent antibiotic course. Hydrogen + methane levels with carbon dioxide correction were plotted against time. Various profiles of the breath test curves were catalogued and compared with respect to their predictive value for symptom response to antibiotics.

RESULTS

Lactulose breath test graphs of 561 patients of all irritable bowel syndrome subtypes were grouped into categories based on their hydrogen + methane levels with respect to time. Of subjects whose hydrogen + methane rise was <20 ppm throughout the test (group 1; N = 95), 94.7% improved after antibiotics (95% CI 90.1-99.3). Of those with a rise <20 ppm within the first 90 min but a rise >50 ppm thereafter (group 3; N = 53), 47.2% improved (95% CI 33.7-60.6). The difference between groups 1 and 3 was statistically significant P < 0.001.

CONCLUSION

A lactulose breath test appears to be useful in predicting response to antibiotics in patients with the irritable bowel syndrome. A hydrogen + methane rise <20 ppm throughout the duration of the test is most predictive. This observation contradicts the classic definition of a positive lactulose breath test.