Stephanie Pun, MD

All Publications

• CORR Insights: Medialization of the Hip's Center with Periacetabular Osteotomy: Validation of Assessment with Plain Radiographs. Clinical orthopaedics and related research Pun, S. Y. 2021

  View details for DOI 10.1097/CORR.0000000000001657

  View details for PubMedID 33587495

• What Are the Early Outcomes of True Reverse Periacetabular Osteotomy for Symptomatic Hip Overcoverage? Clinical orthopaedics and related research Pun, S. Y., Hosseinzadeh, S., Dastjerdi, R., Millis, M. B. 2020

  Abstract

  BACKGROUND: Acetabular overcoverage is associated with pincer-type femoroacetabular impingement (FAI). A subtype of acetabular overcoverage is caused by a deep acetabulum with a negatively tilted acetabular roof, in which acetabular reorientation may be a preferable alternative to rim trimming to uncover the femoral head. We introduced the true reverse periacetabular osteotomy (PAO) in 2003, which in contrast to an anteverting PAO, also flexes and abducts the acetabulum relative to the intact ilium to decrease anterior and lateral femoral head coverage and correct negative tilt of the acetabular roof. To our knowledge, the clinical results of the true reverse PAO have not been evaluated.QUESTIONS/PURPOSES: For a group of patients who underwent reverse PAO, (1) Do patients undergoing reverse PAO demonstrate short-term improvement in pain, function, and hip ROM, and decreased acetabular coverage, as defined by lateral and anterior center-edge angle and Tonnis angle? (2) Are there identifiable factors associated with success or adverse outcomes of reverse PAO as defined by reoperation, conversion to THA, or poor patient-reported outcome scores? (3) Are there identifiable factors associated with early complications?METHODS: Between 2003 and 2017, two surgeons carried out 49 reverse PAOs in 37 patients. Twenty-five patients had unilateral reverse PAO and 12 patients had staged, bilateral reverse PAOs. To ensure that each hip was an independent data point for statistical analysis, we chose to include in our series only the first hip in the patients who had bilateral reverse PAOs. During the study period, our general indications for this operation were symptomatic lateral and anterior acetabular overcoverage causing FAI that had failed to respond to previous conservative or surgical treatment. Thirty-seven hips in 37 patients with a median (range) age of 18 years (12 to 41; interquartile range 16-21) were included in this retrospective study at a minimum follow-up of 2 years (median 6 years; range 2 to 17). Thirty-four patients completed questionnaires, 24 patients had radiographic evaluation, and 23 patients received hip ROM clinical examination. However, seven patients had not been seen in more than 5 years. The clinical and radiographic parameters of all 37 hips that underwent reverse PAO in 37 patients from a longitudinally maintained institutional database were retrospectively studied preoperatively and postoperatively. Adverse outcomes were considered conversion to THA or a WOMAC pain score greater than 10 at least 2 years postoperatively. Patient-reported outcomes, radiographic measurements, and hip ROM were evaluated preoperatively and at most recent follow-up using a paired t-test or McNemar test, as appropriate. Linear regression analysis was used to assess for identifiable factors associated with clinical outcomes. Logistic regression analysis was used to assess for identifiable factors associated with adverse outcomes and surgical complications. All tests were two-sided, and p values less than 0.05 were considered significant.RESULTS: At a minimum of 2 years after reverse PAO, patients experienced improvement in WOMAC pain (-7 [95% CI -9 to -5]; p < 0.001), stiffness (-2 [95% CI -3 to -1]; p < 0.001), and function scores (-18 [95% CI -24 to -12]; p < 0.001) and modified Harris Hip Score (mHHS) (20 [95% CI 13 to 27]; p < 0.001). The mean postoperative hip ROM improved in internal rotation (8° [95% CI 2° to 14°]; p = 0.007). Acetabular coverage, as defined by lateral center-edge angle (LCEA), anterior center-edge angle (ACEA), and Tonnis angle, improved by -8° (95% CI -12° to -5°; p < 0.001) for LCEA, -12° (95% CI -15° to -9°; p < 0.001) for ACEA, and 9° (95% CI 6° to 13°; p < 0.001) for Tonnis angle. The postoperative severity of radiographic arthritis was associated with worse WOMAC function scores such that for each postoperative Tonnis grade, WOMAC function score increased by 12 points (95% CI 2 to 22; p = 0.03). A greater postoperative Tonnis grade was also correlated with worse mHHS, with an average decrease of 12 points (95% CI -20 to -4; p = 0.008) in mHHS for each additional Tonnis grade. Presence of a positive postoperative anterior impingement test was associated with a decrease in mHHS score at follow-up, with an average 23-point decrease in mHHS (95% CI -34 to -12; p = 0.001). Nineteen percent (7 of 37) of hips had surgery-related complications. Four hips experienced adverse outcomes at final follow-up, with two patients undergoing subsequent THA and two with a WOMAC pain score greater than 10. We found no factors associated with complications or adverse outcomes.CONCLUSION: The early clinical and radiographic results of true reverse PAO compare favorably to other surgical treatments for pincer FAI, suggesting that reverse PAO is a promising treatment for cases of pincer FAI caused by global acetabular overcoverage. However, it is a technically complex procedure that requires substantial training and preparation by a surgeon who is already familiar with standard PAO, and it must be carefully presented to patients with discussion of the potential risks and benefits. Future studies are needed to further refine the indications and to determine the long-term outcomes of reverse PAO.LEVEL OF EVIDENCE: Level IV, therapeutic study.

  View details for DOI 10.1097/CORR.0000000000001549

  View details for PubMedID 33296152

• Is Increased Acetabular Cartilage or Fossa Size Associated With Pincer Femoroacetabular Impingement? Clinical orthopaedics and related research Pun, S. Y., Hingsammer, A., Millis, M. B., Kim, Y. 2017; 475 (4): 1013-1023

  Abstract

  Surgical treatment for pincer femoroacetabular impingement (FAI) of the hip remains controversial, between trimming the prominent acetabular rim and reverse periacetabular osteotomy (PAO) that reorients the acetabulum. However, rim trimming may decrease articular surface size to a critical threshold where increased joint contact forces lead to joint degeneration. Therefore, knowledge of how much acetabular articular cartilage is available for resection is important when evaluating between the two surgical options. In addition, it remains unclear whether the acetabulum rim in pincer FAI is a prominent rim because of increased cartilage size or increased fossa size.We used reformatted MR and CT data to establish linear length dimensions of the lunate cartilage and cotyloid fossa in normal, dysplastic, and deep acetabula.We reviewed the last 200 hips undergoing PAO, reverse PAO, and surgical dislocation for acetabular rim trimming at one institution. We compared MR images of symptomatic hips with acetabular dysplasia (20 hips), pincer FAI (29 hips), and CT scans of asymptomatic hips from patients who underwent CT scans for reasons other than hip pain (20 hips). These hips were chosen sequentially from the underlying pool of 200 potential subjects to identify the first 10 male and the first 10 female hips in each group that met inclusion criteria. As a result of low numbers, we included all hips that had undergone reverse PAO and met inclusion criteria. Cartilage width was measured medially from the cotyloid fossa to the lateral labrochondral junction. Cotyloid fossa linear height was measured from superior to inferior and cotyloid fossa width was measured from anterior to posterior. Superior lunate cartilage width (SLCW) and cotyloid fossa height (CFH) were measured on MR and CT oblique coronal reformats; anterior lunate cartilage width (ALCW), posterior lunate cartilage width (PLCW), and cotyloid fossa width (CFW) were measured on MR and CT oblique axial reformats. Cohorts were compared using multivariate analysis of variance with Bonferroni's adjustment for multiple comparisons.Compared with control acetabula, dysplastic acetabula had smaller SLCW (2.08 ± 0.29 mm versus 2.63 ± 0.42 mm, mean difference = -0.55 mm; 95% confidence interval [CI] = -0.83 to -0.27; p < 0.01), ALCW (1.20 ± 0.34 mm versus 1.64 ± 0.21 mm, mean difference = -0.44 mm; 95% CI = -0.70 to -0.18; p = 0.00), CFH (2.84 ± 0.37 mm versus 3.42 ± 0.57 mm, mean difference = -0.59 mm; 95% CI = -0.96 to -0.21; p < 0.01), and CFW (1.98 ± 0.50 mm versus 2.77 ± 0.33 mm, mean difference = -0.80 mm; 95% CI = -1.16 to -0.42; p < 0.0001). Based on the results, we identified two subtypes of deep acetabula. Compared with controls, deep subtype 1 had normal CFH and CFW but increased ALCW (2.09 ± 0.42 mm versus 1.64 ± 0.21 mm; p < 0.001) and PLCW (2.32 ± 0.36 mm versus 2.00 ± 0.32 mm; p = 0.04). Compared with controls, deep subtype 2 had increased CFH (4.37 ± 0.51 mm versus 3.42 ± 0.57 mm; p < 0.01) and CFW (2.76 ± 0.54 mm versus 2.77 ± 0.33 mm; p = 1.0) but smaller SCLW (2.12 ± 0.40 mm versus 2.63 ± 0.42 mm; p < 0.01).Deep acetabula have two distinct morphologies: subtype 1 with increased anterior and posterior cartilage lengths and subtype 2 with a larger fossa in height and width and smaller superior cartilage length.In patients with deep subtype 1 hips that have increased anterior and posterior cartilage widths, rim trimming to create an articular surface of normal size may be reasonable. However, for patients with deep subtype 2 hips that have large fossas but do not have increased cartilage widths, we propose that a reverse PAO that reorients yet preserves the size of the articular surface may be more promising. However, these theories will need to be validated in well-controlled clinical studies.

  View details for DOI 10.1007/s11999-016-5063-1

  View details for PubMedID 27637612

• Hip dysplasia in the young adult caused by residual childhood and adolescent-onset dysplasia. Current reviews in musculoskeletal medicine Pun, S. 2016; 9 (4): 427-434

  Abstract

  Hip dysplasia is a treatable developmental disorder that presents early in life but if neglected can lead to chronic disability due to pain, decreased function, and early osteoarthritis. The main causes of hip dysplasia in the young adult are residual childhood developmental dysplasia of the hip (DDH) and adolescent-onset acetabular dysplasia. These two distinct disease processes affect the growing hip during different times of development but result in a similar deformity and pathomechanism of hip degeneration. Routine screening for DDH and counseling regarding risks for acetabular dysplasia in families with a history of early hip osteoarthritis may allow early identification and intervention in these hips with anatomical risk factors for joint degeneration.

  View details for PubMedID 27613709

• CORR Insights(®): The 2015 Frank Stinchfield Award: Radiographic Abnormalities Common in Senior Athletes With Well-functioning Hips but Not Associated With Osteoarthritis. Clinical orthopaedics and related research Pun, S. Y. 2016; 474 (2): 353-356

  View details for DOI 10.1007/s11999-015-4454-z

  View details for PubMedID 26178757

  View details for PubMedCentralID PMC4709321

• Review: femoroacetabular impingement. Arthritis & rheumatology Pun, S., Kumar, D., Lane, N. E. 2015; 67 (1): 17-27

  View details for DOI 10.1002/art.38887

  View details for PubMedID 25308887

  View details for PubMedCentralID PMC4280287

• Nonarthroplasty Hip Surgery for Early Osteoarthritis RHEUMATIC DISEASE CLINICS OF NORTH AMERICA Pun, S. Y., O'Donnell, J. M., Kim, Y. 2013; 39 (1): 189-?

  Abstract

  The most favorable mechanical environment for the hip is one that is free of both instability and impingement, creating a concentric articulation with optimum femoral head coverage by the acetabulum. Anatomic variations such as acetabular dysplasia with associated instability, and femoroacetabular impingement with abnormal constraint, will lead to abnormal joint mechanics, articular damage, and osteoarthritis. Surgical techniques such as periacetabular osteotomies, and femoral and acetabular osteoplasties enable correction of anatomic variations that cause mechanical damage to the hip joint, thereby potentially preventing or delaying development of osteoarthritis and subsequent need for joint replacement.

  View details for DOI 10.1016/j.rdc.2012.11.004

  View details for Web of Science ID 000315170300011

  View details for PubMedID 23312416

• An anatomic classification for heterotopic ossification about the hip. Journal of orthopaedics DeBaun, M. R., Ziino, C. n., LaPrade, C. n., Pun, S. n., Avedian, R. S., Bellino, M. J. 2020; 21: 228–31

  Abstract

  Retrospective cohort.Heterotopic ossification (HO) about the hip is a debilitating condition that can occur after fixation for acetabular fractures, total hip replacement, or polytrauma with closed head injuries. No classification exists that informs surgical treatment.To establish a classification system for HO about the hip by reviewing a consecutive series of HO at a single institution. It was hypothesized that HO about the hip could be grouped into a novel classification scheme based upon the location and involved structures of the hip.Retrospective chart review of single center's case log for HO excision from 2004 to 2018 was performed. Inclusion criteria included all patients undergoing excision of heterotopic bone excision about the hip. Demographic data, pre and post hip range of motion, surgical approach for each surgery, index surgery date and interval to excision are reported as well as presence and location of HO and Brooker classification.A total of 36 patients (21 men and 15 women) and 40 hips were identified meeting inclusion criteria. The mean age at the time of the index surgery was 47 (range, 16-77 years). Traumatic injury with fracture (35%) included 9 acetabular fractures (22%), 2 long bone fractures (5%) treated with intramedullary devices, one displaced femoral neck fracture (2%), and one pelvic ring injury (2%). Total hip arthroplasty accounted for 32% of patients. Brooker classification was type 4 (35%), 3 (25%), 2 (23%), 1(17%) which translated to 55% anterior, 48% posterior, 3% medial with respect to location. Average improvement in hip flexion and abduction was 22 and 8°, respectively.This study identified discrete locations for heterotopic ossification following hip or acetabulum surgery. Both posterior and anterior structures are implicated in the formation of HO, and this investigation presents a novel classification to guide surgical approach for HO excision based upon location.

  View details for DOI 10.1016/j.jor.2020.03.038

  View details for PubMedID 32273662

  View details for PubMedCentralID PMC7132042

• THE LOWER EXTREMITY GRADING SYSTEM (LEGS) TO EVALUATE BASELINE LOWER EXTREMITY PERFORMANCE IN HIGH SCHOOL ATHLETES INTERNATIONAL JOURNAL OF SPORTS PHYSICAL THERAPY Smith, J., DePhillipo, N., Azizi, S., McCabe, A., Beverine, C., Orendurff, M., Pun, S., Chan, C. 2018; 13 (3): 401–9

  View details for DOI 10.26603/ijspt20180401

  View details for Web of Science ID 000442339400005

• Successful directional thoracic erector spinae plane block after failed lumbar plexus block in hip joint and proximal femur surgery. Journal of clinical anesthesia Darling, C. E., Pun, S. Y., Caruso, T. J., Tsui, B. C. 2018; 49: 1–2

  View details for PubMedID 29775780

• Reconstruction of both the medial and lateral collateral ligaments in the elbow using a single graft: a new technique of reconstruction. Techniques in Shoulder & Elbow Surgery Pun, S. Y., Safran, M. R. 2012; 13 (1): 6-10
• Effect of bupivacaine on chondrocyte viability. spine journal Dragoo, J. L., Pun, S. Y. 2010; 10 (2): 172-173

  View details for DOI 10.1016/j.spinee.2009.11.015

  View details for PubMedID 20142073

• Effect of Gender and Preoperative Diagnosis on Results of Revision Total Knee Arthroplasty Open Scientific Meeting of the Knee-Society Pun, S. Y., Ries, M. D. SPRINGER. 2008: 2701–5

  Abstract

  Recent studies question an effect of gender on outcome of primary TKA. We questioned whether the results of revision TKA were affected by gender. We separated 67 revision TKAs by gender and preoperative diagnosis into four groups (arthrofibrosis, infection, instability, and wear and loosening). Each revision TKA was individually matched by age and gender to two primary TKAs. Postoperative Knee Society pain and function scores after revision TKA were lower than for primary TKA for both females and males. However, postoperative Knee Society pain and function scores were similar in males and females. Postoperative pain and function scores were lower for all revision groups compared with primary TKA, except for pain and function scores after revision for instability. Postoperative pain and function scores were higher for instability and wear or loosening than for arthrofibrosis. Our data suggest the results of revision TKA are affected by preoperative diagnosis but not gender.Level III, retrospective matched cohort study. See Guidelines for Authors for a complete description of levels of evidence.

  View details for DOI 10.1007/s11999-008-0451-9

  View details for Web of Science ID 000259909000021

  View details for PubMedID 18726656

• Periodic rewetting enhances the viability of chondrocytes in human articular cartilage exposed to air JOURNAL OF BONE AND JOINT SURGERY-BRITISH VOLUME Pun, S. Y., Teng, M. S., Kim, H. T. 2006; 88B (11): 1528-1532

  Abstract

  Desiccation of articular cartilage during surgery is often unavoidable and may result in the death of chondrocytes, with subsequent joint degeneration. This study was undertaken to determine the extent of chondrocyte death caused by exposure to air and to ascertain whether regular rewetting of cartilage could decrease cell death. Macroscopically normal human cartilage was exposed to air for 0, 30, 60 or 120 minutes. Selected samples were wetted in lactated Ringer's solution for ten seconds every ten or 20 minutes. The viability of chondrocytes was measured after three days by Live/Dead staining. Chondrocyte death correlated with the length of exposure to air and the depth of the cartilage. Drying for 120 minutes caused extensive cell death mainly in the superficial 500 microm of cartilage. Rewetting every ten or 20 minutes significantly decreased cell death. The superficial zone is most susceptible to desiccation. Loss of superficial chondrocytes likely decreases the production of essential lubricating glycoproteins and contributes to subsequent degeneration. Frequent wetting of cartilage during arthrotomy is therefore essential.

  View details for DOI 10.1302/0301-620X.88B11.18091

  View details for Web of Science ID 000242303100023

• Utilization of medical acupuncture at the Stanford University Complementary Medicine Clinic: a two-year retrospective study. Medical Acupuncture Fredericson, M., Pun, S., Nelson, L., Speigel, D. 2002; 13 (3)