A novel technique for subscapularis repair in total shoulder arthroplasty.

Anatomic total shoulder arthroplasty, when used for treatment of primary glenohumeral arthritis, is historically very successful. We propose a novel technique for subscapularis repair during closure of a deltopectoral approach to the shoulder with subscapularis peel. Our technique allows for early motion following surgery and also provides for improved subscapularis repair integrity and resilience during postoperative rehabilitation. Postoperatively, we allow passive and active assisted range of motion at week 1, limited active range of motion at week 2, and unrestricted external rotation range of motion beginning at week 6. The use of our technique has led to improved patient outcomes with regard to range of motion postoperatively following anatomic total shoulder arthroplasty and we recommend its adoption into practice.

Effectiveness of an Orthopaedic Trauma Research Fellowship to Produce Successfully Matching Residents.

OBJECTIVE: Orthopaedics is becoming increasingly competitive. Approximately 25% of applicants to orthopaedic surgery go unmatched each year. The mean US Medical Licensing Examination step scores and average publication numbers have increased markedly in recent years. Reapplicants have a match rate of <60%. This study describes the results of an orthopaedic trauma research fellowship and its effectiveness in obtaining a successful orthopaedic match. METHODS: A 1 to 2-year research fellowship was established at a level 1 academic trauma center. Prefellowship and fellowship metrics of 11 fellows were recorded, including undergraduate and medical schools; step-1 + step-2 scores; Alpha Omega Alpha appointment; and publication, podium, poster, and chapter accomplishments. RESULTS: The average step-1 score of the fellows was 218 (range, 192 to 252) and 232 (range, 212 to 254) for step-2. Seven of 11 fellows were reapplicants. Prefellowship, the average number of journal publications was 1, one podium, two posters, and zero textbook chapters. During fellowship, the average publications was 5, five podiums, six posters, and 1.5 textbook chapters. Ten of 11 fellows successfully matched into an orthopaedic residency, with six of seven being reapplicants. CONCLUSIONS: Six of 7 reapplying fellows (86%) successfully matched highlighting the effectiveness of this fellowship. Research fellowships should be considered as an excellent choice for applicants who may be less than ideal candidates or reapplicants.

Immediate Weightbearing After Operative Treatment of Bimalleolar and Trimalleolar Ankle Fractures: Faster Return to Work for Patients with Nonsedentary Occupations.

The goal of this study was to compare immediate weightbearing (IWB) and traditional weightbearing (TWB) postoperative protocols in unstable ankle fractures, as this has not been compared in prior works. We hypothesize that an immediate weightbearing protocol after ankle fracture fixation will lead to an earlier return to work. An ankle fracture registry was reviewed for operatively treated unstable bimalleolar and trimalleolar ankle fractures at an ambulatory surgery center and followed up at associated outpatient clinics. All fracture cases reviewed occurred from 2009 to 2015. Immediate weightbearing patients were placed into a controlled ankle motion (CAM) boot and allowed to fully bear weight the day of surgery. Traditional weightbearing patients were placed into a CAM boot with 6 weeks of non-weightbearing. Demographics, fixation technique, and injury characteristics were surveyed. Physical job demand was stratified for 69 patients meeting the inclusion criteria (34 IWB and 35 TWB). The main outcome of this study was measured as the time to return to work. Subgroup analysis of patients with nonsedentary jobs demonstrated a significantly earlier return to work for the IWB group (5.7 versus 10.0 weeks, p = .04). Multivariate regression analysis identified a statistically significant 2.25-week (p = .05) earlier return to work for the IWB group after adjustment for occupational physical demand, demographics, fracture characteristics, and participation in a light work period before full work return. In patients with nonsedentary jobs, an IWB protocol after operative management of bimalleolar and trimalleolar ankle fractures resulted in an earlier return to work compared with traditional protocols.

Operative Management of Rib Synostosis and Malunion: A Case Report.

CASE: We present a complex case of a 56-year-old man with multiple left-sided rib pathology including nonunion, rib heterotopic ossification (HO) forming a rib-to-rib synostosis, and rib malunion. After a major forequarter trauma and failed conservative management, followed by scapula reconstruction and rib recontouring, the surgical resection of the rib synostosis, reconstruction of a rib nonunion, and contouring of rib malunions are described. The patient was followed up clinically for 1 year after the final procedure and demonstrated marked improvement in functional outcome. CONCLUSION: In the setting of complex forequarter malunion and nonunion, resolution of painful rib nonunion and synostosis can be effectively managed with HO resection and rib reconstruction.

Early resection of ectopic bone in patients with heterotopic ossification about the hip after trauma.

OBJECTIVES: Heterotopic ossification (HO) is a common complication in patients who have sustained high-energy trauma to the hip region. Traditionally, resection is performed after ectopic bone maturation. We hypothesized that early HO resection in patients with hip ankylosis after trauma can be performed with little chance of recurrence. DESIGN: Retrospective clinical cohort. SETTING: Level I Trauma Center PATIENTS/PARTICIPANTS: 14 patients with resection of HO about the hip performed by the senior author during a six-year period. INTERVENTION: Early resection of Brooker Class III or IV HO. MAIN OUTCOME MEASUREMENTS: The original injuries, risk factors for HO, post-traumatic clinical course including the workup for HO, times from fixation to resection, surgical approach, and complications were recorded. Records were reviewed to document pre and postoperative hip motions. Pre and post-operative x-rays and CT scans were reviewed to classify the HO and localize the ectopic mass. RESULTS: Mean injury to resection interval was 6.8-months. Nine of 14 (64%) patients were followed for a mean of 32.9-months post-resection. Indications for resection included pain, stiffness, and evolving sciatic nerve lesions. Risk factors were male gender, brain injury, and extended iliofemoral and Kocher-Langenbeck surgical approaches. Complications included gluteal vein laceration, draining wounds, and recurrence. Mean flexion-extension arc of motion was 18° (range = 0-70°) preoperatively, 100° (range = 85-125°) intra-operatively, and 94° (range = 20-110°) at final follow-up. HO recurred in nine patients; functionally significant in one. CONCLUSION: Early resection of HO around the hip may be performed with little chance of symptomatic recurrence. LEVEL OF EVIDENCE: This is a Level IV retrospective case series.

Patient-Level Value Analysis: An Innovative Approach to Optimize Care Delivery.

BACKGROUND: An increasing emphasis has been placed on developing value-based care delivery systems in orthopaedics to combat rising health care costs. The goal of these systems is to both measure and improve the provisional value of care. Patient-level value analysis creates a mechanism to quantify and optimize value within a procedure, in contrast to traditional methods, which only measures value. The purpose of this study was to develop a patient-level value analysis model and determine the efficacy of this model to improve value in orthopaedic care. METHODS: Patients treated operatively for isolated closed ankle fractures at a single level 1 trauma center were prospectively identified. Short musculoskeletal function assessment was collected at the time of the initial clinical presentation and 6 months postoperatively. The cost of care was determined using time-driven activity-based costing, which included personnel, supplies, length of stay, implants, pharmacy, and radiology. Value was defined as each patient's change in the outcome score divided by their cost as determined by time-driven activity-based costing. A multiple linear regression was performed to determine which aspects of care significantly predicted value. RESULTS: Forty-nine patients met inclusion/exclusion criteria. The multiple linear regression indicated treatment by physician D (ß = -0.135, P = 0.04) and inpatient stay (ß = -0.468, P < 0.01) were predictors of lesser value and represent areas for potential care pathway and value improvement. CONCLUSIONS: Patient-level value analysis represents a paradigm shift in the quantification of value. We recommend surgeons, practices, and health care systems begin implementing a system to quantify and optimize the value of care provided. LEVEL OF EVIDENCE: Level III. See Instructions for Authors for a complete description of levels of evidence.

Minimally Invasive Endoscopic-Assisted Technique for Implant Removal After Pelvic Bridge Plating.

Subcutaneous internal plate fixation for anterior pelvic ring injuries has become more common, but implants require removal, usually by 12 weeks. The purpose of this article is to report a novel, minimally invasive, endoscopic-assisted technique for the removal of subcutaneous anterior pelvic plates safely and atraumatically without violating the underlying fascia.

Posterior Scapula Approaches: Extensile and Modified Judet.

The Extensile Judet has been widely used in the management of scapula fractures. An enhanced understanding of these injuries, however, has allowed for the strategic development of alternative methods in which soft tissues may be better spared. The purpose of this video is to highlight the indications and techniques for 2 posterior approaches to the scapula: The Extensile Judet and the Modified Judet. Case 1 demonstrates the Modified Judet approach. The "boomerang" incision follows the curve of the scapula spine and vertebral border, and fixation occurs through an intermuscular window. Case 2 illustrates the Extensile Judet. The incision is identical to that of the Modified Judet, but differs in that posterior musculature is elevated in 1 periosteocutaneous flap. The utility of 2 different posterior approaches to the scapula are described. Both include the same incision, but differ with regards to management of the musculature overlying the fracture. The Modified Judet lacks the exposure of the Extensile approach, but significant soft-tissue trauma is avoided. Regarding the Extensile Judet, substantial tissue trauma is incurred to gain the exposure necessary for complex fracture patterns. Reduction goals, wound closure, and postoperative care remain the same for both approaches. Both approaches are valuable in terms of operative management of scapula fractures, although certain populations may benefit from tissue-sparing procedures.

Minimally invasive anterior pelvic internal fixation: An anatomic study comparing Pelvic Bridge to INFIX.

OBJECTIVES: Anterior external fixation for pelvic ring fractures has shown to effectively improve stability and reduce mortality. However, these fixators can be associated with substantial morbidity such as pin tract infection, premature loss of fixation, and decreased quality of life in patients. Recently, two new methods of subcutaneous anterior pelvic internal fixation have been developed; the INFIX and the Pelvic Bridge. These methods have the purported advantages of lower wound complications, less surgical site pain, and improved quality of life. We sought to investigate the measured distances to critical anatomic structures, as well as the qualitative and topographic differences notable during implantation of both devices in the same cadaveric specimen. MATERIALS AND METHODS: The Pelvic Bridge and INFIX were implanted in eleven fresh cadavers. Distances were then measured to: the superficial inguinal ring, round ligament, spermatic cord, lateral femoral cutaneous nerve (LFCN), femoral nerve, femoral artery, and femoral vein. Observations regarding implantation and topography were also recorded. RESULTS: The INFIX had greater measured distances from all structures except for the LFCN, in which its proximity placed this structure at risk. Neither device appears to put other critical structures at risk in the supine position. Significant implantation and topographic differences exist between the devices. The INFIX application lacked "safety margins" concerning the LFCN in 10/11 (90.9%) specimens, while Pelvic Bridge placement lacked "safety margins" with regard to the right superficial ring (1/11, 9%) and the right spermatic cord (1/11, 9%). CONCLUSIONS: Both the Pelvic Bridge and INFIX lie at safe distances from most critical pelvic structures in the supine position, though INFIX application places the LFCN at risk.

Publication of Podium Presentations at the Orthopaedic Trauma Association Annual Meetings: 2008-2012.

OBJECTIVE: To determine journal publication rates of podium presentations from the OTA Annual Meetings between 2008 and 2012. METHODS: Podium presentations from the 2008 to 2012 OTA annual meeting were compiled from the Annual Meeting archives. During December 2016, and Google Scholar were performed using individual keywords in the abstract title and content. The results were reviewed for matches to the meeting abstracts with regard to the title, authors, and abstract content. Yearly publication rates were calculated, along with time to publication and common journals for publication. RESULTS: The publication rate for the 357 podium abstracts presented at the OTA between 2008 and 2012 was 72.8%. Eighty-one percent of abstracts were from the US institutions. The mean time to publication from podium presentation was 23.4 months, and the most common journals of publication were Journal of Orthopaedic Trauma (45.4%) and The Journal of Bone & Joint Surgery (15.3%). CONCLUSIONS: The publication rate of the podium presentations at the OTA Annual Meeting from 2008 to 2012 has increased since previous years. Compared with other orthopaedic subspecialty and nonorthopaedic specialty meetings, the OTA publication rate is among the highest in the medical field. OTA annual meetings are an opportunity for early access to high-quality research in the area of orthopaedic trauma.

Comparison of 2 versus 3 dimensional fracture mapping strategies for 3 dimensional computerized tomography reconstructions of scapula neck and body fractures.

Fracture mapping has been used in the understanding of injury patterns in different bones. To our knowledge, there are no applications of this technique using three-dimensional (3D) morphologic fracture characteristics. Previously, scapula fractures were mapped by transferring information from 3D computed tomography to a two-dimensional (2D) template. Cole et al. determined that 3D Computerized Tomography (CT) scans were more reliable compared to plain radiographs in terms of scapular angulation, translation, and glenopolar angle measurements. Thus, we hypothesized that if there is a difference between fracture lines drawn in 3D and in 2D, then the 3D mapping would yield more accurate fracture patterns. We completed a retrospective, comparative study (evidence level III) utilizing CT imaging from a single center scapular registry. We studied ten patients with scapula fractures in whom bilateral CT scans were obtained. Fractures were mapped both two and three-dimensionally, and we measured deviations between the fracture lines that were drawn with each approach. The measured deviations ranged from 10.4 mm to 28.0 mm when comparing 2D versus 3D techniques, with the mean deviation being 4.0 mm and 10.4 mm, respectively. Half of the 2D renderings possessed hidden fracture lines that were later revealed on 3D imaging. Three-dimensional renderings were more accurate when compared to 2D fracture mapping methods. This more accurate technique will allow for better understanding of 3D morphology and provide a basis for future fracture mapping in any bone. Accurate mapping is important because surgical approach, reduction, fixation, and implant design and selection are based on fracture patterns. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:265-271, 2018.

Anatomic Study of Subcoracoid Morphology in 418 Shoulders: Potential Implications for Subcoracoid Impingement.

BACKGROUND: Subcoracoid impingement has been implicated as a cause of anterior shoulder pain and subscapularis tendon tears. PURPOSE/HYPOTHESIS: The purpose of this study was to evaluate the bony anatomy of the coracoid process and the subcoracoid space. We hypothesized that age-related changes that may contribute to subcoracoid impingement occur in the subcoracoid space. STUDY DESIGN: Descriptive laboratory study. METHODS: In total, 418 skeletal shoulder specimens were included in this study. We utilized 214 shoulders from a young cohort (25-35 years of age) and 204 shoulders from an older cohort (>55 years of age) for comparison. We evaluated several morphological characteristics of the coracoid process and the subcoracoid space: coracoid width, coracoid shape, coracoid thickness, and subcoracoid distance. Each coracoid was observed for the presence of spurring or other morphological changes. RESULTS: The mean anteroposterior (AP) thickness of the coracoid tip was 7.9 and 9.4 mm in our young female and male cohorts, respectively, while the mean AP thickness was 8.1 and 9.7 mm in our older female and male cohorts, respectively. The coracoid tip was hooked in 31 of 108 young female shoulders compared with 55 of 102 older female shoulders, and the coracoid tip was hooked in 25 of 106 young male shoulders compared with 45 of 102 older male shoulders. The mean subcoracoid distance in neutral rotation was 14.8 and 12.5 mm in young and older female shoulders, respectively, while the mean subcoracoid distance in internal rotation in these same cohorts was 8.7 and 7.0 mm, respectively. The mean subcoracoid distance in neutral rotation was 14.8 and 13.3 mm in young and older male shoulders, respectively, while the mean subcoracoid distance in internal rotation was 8.6 and 8.1 mm in young and older male shoulders, respectively. CONCLUSION: The principal findings of our study demonstrate that anatomic changes implicated in subcoracoid impingement may be developmental and worsen with age. The subcoracoid space was narrower in our older cohort of shoulders. Additionally, these older shoulders also had a greater AP width and a more hooked coracoid compared with young shoulders. CLINICAL RELEVANCE: Narrowing of the subcoracoid space has been shown to be implicated as a cause of anterior shoulder pain and subscapularis tendon tears. This is the first study to show that the morphological changes implicated in subcoracoid impingement become more prevalent with age. This may help to explain the increasing prevalence of subscapularis tendon tears in older patients. Furthermore, subcoracoid decompression may be seen as an option for older patients with anterior shoulder pain and subscapularis tendon tears.

Open Reduction and Internal Fixation of a Middle-Third Clavicle Fracture with a Superior Plate.

Open reduction and internal fixation has become a reliable technique to treat complex middle-third clavicle fractures (AO/OTA B-15). Nonoperative treatment of these fractures may result in higher rates of symptomatic malunion, nonunion, dissatisfaction with cosmetic appearance, and even dysfunction and muscular weakness. Risk factors such as substantial displacement or comminution, far lateral fractures, fractures in the elderly, open fractures, or those occurring in polytrauma scenarios are appropriate indications for surgery. The aim of the procedure is to reconstitute the initial curvature and length of the clavicle, restore a normal connection from the arm to the axial skeleton, and provide stable fixation of the proximal and distal fragments, to allow an immediate full range of motion during rehabilitation. The procedure includes the following steps. Step 1: Place the patient in a beach-chair, semi-sitting position.Step 2: Make a transverse skin incision along the anteroinferior aspect of the clavicle.Step 3: Expose the fracture site, identify and prepare the fragments unless they are comminuted, and preserve soft-tissue attachments to the extent possible.Step 4: Reduce the fragments by direct or indirect manipulation, and maintain the reduction with clamps, Kirschner wires, or mini-fragment plates. Consider bridging comminuted zones to allow secondary fracture-healing.Step 5: Apply a contoured plate to the superior or anterior surface of the clavicle, and obtain at least 6 cortices of fixation on each side with strategic nonlocking and locking screws. The working length of the plate is more important than the number of screws or cortices.Step 6: Obtain a single intraoperative anteroposterior radiograph of the clavicle.Step 7: Separately close the wound in layers (deltotrapezial fascia, platysma, and skin). Apply sterile dressings and a sling. The patient is discharged home on the same day if the injury is isolated, and a full range of motion of the affected shoulder is allowed immediately. The patient is expected to regain full function and strength of the arm once healing occurs.

The Pelvic Bridge: A Subcutaneous Approach for Anterior Pelvic Fixation.

INTRODUCTION: An alternative method to external fixation for the treatment of unstable anterior pelvic ring injuries, termed the pelvic bridge technique, provides equivalent results with fewer complications and is performed using occipital cervical rods subcutaneously, with fixation into the iliac wings and parasymphyseal bone. STEP 1 PREOPERATIVE PLANNING: For preoperative planning, review the appropriate imaging, including radiographs and computed tomography (CT) scans, to mesh the findings on imaging to the clinical picture of the patient and ensure that the patient meets operative criteria and that none of the contraindications are present. STEP 2 PATIENT POSITIONING: Position the patient to facilitate anterior and posterior fixation. STEP 3 APPROACH: Make the incisions necessary to expose the osseous contour where fixation will be utilized. STEP 4 CONTOURING THE PLATE-ROD CONSTRUCT: Carefully contour the plate-rod construct, which is necessary to minimize postoperative complications. STEP 5 PASSING THE PLATE-ROD CONSTRUCT: Use care when inserting the rod as doing so will help to avoid neurovascular complications. STEP 6 ACHIEVING ADEQUATE REDUCTION: To recreate pelvic stability, the pelvic ring needs to heal in as close to anatomic position as possible and there are multiple methods that help to obtain an adequate reduction. STEP 7 FRACTURE FIXATION: Multiple constructs may be used to stabilize the anterior pelvic ring, but the fundamental principle is to attach the 2 hemipelves to achieve stability, and the location where fixation can be achieved depends on the fracture pattern. STEP 8 WOUND CLOSURE: Ensure meticulous closure to reduce the chance of infection and achieve appropriate soft-tissue coverage over hardware. STEP 9 REHABILITATION: Early mobilization is a fundamental goal of this procedure, but the time to full weight-bearing is dependent on fracture characteristics and healing. RESULTS: Anterior pelvic internal fixation (APIF) using the pelvic bridge technique has been demonstrated to have significantly fewer complications than APEF2.

Calcaneocuboid Joint Arthritis of the Midfoot Precedes Tibiotalar Joint Arthritis.

Surgical models have best shown the relationship between ankle and mid-foot osteoarthritis, although findings regarding the calcaneocuboid joint have varied. To the authors' knowledge, no studies have evaluated the relationship between degenerative changes across the tibiotalar and calcaneocuboid joints. The goal of this study was to determine whether such a relationship exists and which joint degenerates first. A single examiner evaluated 694 tibiotalar and calcaneocuboid joints to determine the presence of osteoarthritis. Multiple linear regression analysis was conducted with a standard P value cutoff (P<.05) and 95% confidence interval. The average incidence of tibiotalar and calcaneocuboid osteoarthritis in specimens older than 40 years was compared with the incidence in those 40 years and younger. A positive correlation between tibiotalar and calcaneocuboid osteoarthritis was noted. African-American subjects were less likely than white subjects to have tibiotalar osteoarthritis. The finding of right and left tibiotalar and calcaneocuboid osteoarthritis in subjects 40 years and younger showed that midfoot arthritis was significantly more common than arthritis of the ankle. The prevalence of calcaneocuboid osteoarthritis remains stable after 40 years of age, and the prevalence of tibiotalar osteoarthritis approaches that of calcaneocuboid osteoarthritis. Calcaneocuboid osteoarthritis precedes tibiotalar osteoarthritis. Altered biomechanics involved in calcaneocuboid osteoarthritis are transferred to the tibiotalar joint, leading to tibiotalar osteoarthritis as the subject ages. Early education, surveillance, physical therapy, shoe adjustment, and orthotics may help to reduce the forces across the midfoot and prevent ankle arthritis in the long term. [Orthopedics. 2016; 39(6):e1112-e1116.].

Ipsilateral Tibiotalar Joint Osteoarthritis Transferred to the Contralateral Tibiotalar Joint.

Classically, it is thought that pain or disability in one leg can stress the contralateral leg, leading to similar symptoms. The mechanism of action for subsequent dysfunction in the healthy limb is thought to involve compensatory changes that are used as a means to reduce stance phase time on the injured limb. This is believed to increase the forces distributed across the healthy limb, ultimately leading to injury. This belief has been challenged, as supportive literature is sparse. The goal of this study was to determine whether an association between tibiotalar (TT) osteoarthritis (OA) in the right vs left lower extremity exists, and whether injury to one lower extremity leads to degeneration in the contralateral lower extremity. The authors evaluated 704 TT joints to determine the presence of OA. A multiple linear regression was performed using a standard P value cutoff (P<.05) and 95% confidence interval. The absolute value of the difference between right and left TT OA was compared for specimens in each decade of life. Multiple regression analysis revealed a positive correlation between right and left TT OA, after correcting for age, sex, and race. Right TT vs left TT had a slope of 0.489 with a P value approaching 0. Findings indicated the absolute value of the difference between right and left TT OA was not zero, and this difference remains significant throughout life. Based on these findings, OA in one ankle does not appear to lead to accelerated OA in the contralateral ankle. [Orthopedics. 2016; 39(4):e664-e667.].

Bilateral Pars Defects at the L4 Vertebra Result in Increased Degeneration When Compared With Those at L5: An Anatomic Study.

BACKGROUND: Cadaveric studies have examined disc degeneration at the L4-L5 and L5-S1 motion segments; however, we are not aware of another study that has examined the relationship between bilateral spondylolysis and its effect on degenerative disc disease at those levels. This may have been overlooked by researchers owing to the majority of spondylolysis occurring at the L5 vertebra. QUESTIONS/PURPOSES: Using osteologic specimens from a collection that included individuals who died in one city in the USA between 1893 and 1938, we asked: (1) do specimens with bilateral spondylolysis (bilateral pars defects) have increased levels of disc degeneration, at their respective motion segments, when compared with matched controls without spondylolysis, and (2) is the finding of a bilateral pars defect associated with more severe arthritis at L4-L5 than at L5-S1? METHODS: An observational study was performed on 665 skeletal lumbar spines from the Hamann-Todd Osteologic Collection at the Cleveland Museum of Natural History (Cleveland, OH, USA). The specimens included 534 males and 131 females ranging from 17 to 87 years old, with a nearly bell-shaped distribution of ages for males and a larger proportion of younger ages in the female specimens. Of those with spondylolysis, 81 had a defect at L5 and 14 had a defect at L4. The gross specimens were examined subjectively for evidence of arthrosis. At the time of examination, specific attention was not paid to the coexisting presence or absence of spondylolysis nor was the examiner blinded to the age of the specimens. Disc degeneration was measured by the classification of Eubanks et al., a modified version of the Kettler and Wilke classification. Linear regression was performed to derive a formula that would predict the amount of disc degeneration at L4-L5 and L5-S1 for the normal control population given a specimen's age, sex, and race. We then used this formula to evaluate the difference in disc degeneration at the corresponding level of the pars defect that is greater than the predicted amount for a control without spondylolysis. This allowed us to conclude that any significant differences found between the L4-L5 and L5-S1 cohorts were attributable to factors not simply inherent to their functional position in the spine of an individual without a bilateral pars defect. RESULTS: L4 spondylolysis and L5 spondylolysis showed greater amounts of degeneration compared with that of matched controls (L4 controls: mean = 1.52, SD = 0.74; L4 spondylolysis: mean = 3.21, SD = 0.87; p < 0.001; L5 controls: mean = 0.97, SD = 0.48; L5 spondylolysis: mean = 2.06, SD = 0.98; p < 0.001). When we controlled for the expected amount of degenerative disc disease at each level in controls, the observed degeneration was more severe at L4-L5 than at L5-S1 (p = 0.008, R-squared = 18.6). CONCLUSIONS: L4-L5 and L5-S1 bilateral spondylolysis groups had increased presence of degenerative disc disease compared with those without bilateral spondylolysis. For the same degree of spondylolysis, the observed amount of disc degeneration was greater at the L4-5 motion segment compared with L5-S1. CLINICAL RELEVANCE: Although not as common as the spondylolysis at L5-S1, we believe that our findings support that patients with L4-L5 spondylolysis can expect a greater degree of degenerative disc disease and increasing clinical symptoms. Multiple factors in the sacropelvic geometry of an individual, facet morphologic features at L4-L5, and the absence of the iliolumbar ligament at this level are possible contributing factors to the findings of this study.