Clinical Focus

  • Child and Adult Hip Preservation Surgery
  • Hip Dysplasia
  • Periacetabular Osteotomy (PAO) for Acetabular Dysplasia, Acetabular Retroversion, Coxa Protrusio
  • Hip Arthroscopy for Femoroacetabular Impingement (FAI), Labral Tears, Hip Cartilage Defects
  • Surgical Hip Dislocation
  • Pelvic and Femoral Osteotomies
  • Slipped Capital Femoral Epiphyses
  • Legg-Calve-Perthes Disease
  • Orthopaedic Surgery

Academic Appointments

Administrative Appointments

  • Director, Hip Preservation Program at Stanford Children's Health (2015 - Present)

Boards, Advisory Committees, Professional Organizations

  • Diplomate, American Board of Orthopaedic Surgery (ABOS)
  • Member, American Academy of Orthopaedic Surgeons (AAOS)
  • Member, Western Orthopaedic Association (WOA)
  • Member, California Orthopaedic Association (COA)
  • Member, International Society for Hip Arthroscopy (ISHA)

Professional Education

  • Board Certification, Orthopaedic Surgery, American Board of Orthopaedic Surgery (2015)
  • Fellowship, Harvard Medical School, Child & Adult Hip Preservation Surgery (2013)
  • Residency, Stanford University, Orthopaedic Surgery (2012)
  • Internship, Stanford University, Orthopaedic Surgery (2008)
  • Medical Education, University of California San Francisco, CA (2007)
  • Undergraduate, Stanford University, CA (2003)

Community and International Work

  • Operation Rainbow



    Ongoing Project


    Opportunities for Student Involvement


Current Research and Scholarly Interests

Dr. Pun specializes in the treatment of complex hip disorders with surgical hip preservation options for children, adolescents, and adults. Her goal is to enhance hip function in active individuals and to prevent the early development of hip osteoarthritis.

Her areas of expertise are acetabular dysplasia, developmental dysplasia of the hip (DDH), femoroacetabular impingement (FAI), acetabular labral tears, hip cartilage defects, slipped capital femoral epiphysis (SCFE), Perthes disease, and deformities of the pelvis and proximal femur.

She offers both arthroscopic and open hip preservation options, such as periacetabular osteotomy (PAO), pelvic and femoral osteotomies, surgical hip dislocations, and hip arthroscopy for repair of labral tears and chondral defects.

Dr. Pun received her undergraduate degree from Stanford University and medical degree from UCSF School of Medicine. She then completed the Stanford Orthopaedic Surgery Residency Program, during which she developed a profound interest in hip function and preservation. She subsequently pursued fellowship training in Hip Preservation Surgery at the world-renowned Boston Children’s Hospital and Harvard Medical School.

Dr. Pun’s research interests include advancing knowledge of the dynamic pathoanatomy in hip instability and hip impingement, defining the unique anatomy of the dysplastic acetabulum, developing new surgical techniques for improving hip function, and clinical outcomes of hip preservation surgery.

2014-15 Courses

All Publications

  • Hip dysplasia in the young adult caused by residual childhood and adolescent-onset dysplasia. Current reviews in musculoskeletal medicine Pun, S. 2016


    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 DOI 10.1007/s12178-016-9369-0

    View details for PubMedID 27613709

  • 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. J. 2016


    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

  • 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-?


    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

  • 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

  • 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 Web of Science ID 000346917700004

    View details for PubMedID 25308887

  • 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 CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Pun, S. Y., Ries, M. D. 2008; 466 (11): 2701-2705


    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


    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

    View details for PubMedID 17075104

  • 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)