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Patients › Hip

Periacetabular osteotomy

PDF Evidence Consent
Updated Sep 2026
Illustration: hip

Why this operation has been suggested

Periacetabular osteotomy means cutting the bone around your hip socket and turning it so the socket covers the ball of the hip joint better. It is usually offered to younger adults with a hip socket that did not form deeply enough, a problem called hip dysplasia. This can cause groin pain, pain on the side of the hip, a limp, and daily pain that settles with rest. Left alone, it can lead to early wear-and-tear arthritis.

For long-standing problems we usually try non-operative care first, such as changing your activities or physiotherapy. We consider this operation when those steps have not given enough improvement. The aim is pain relief, better hip function and a more stable hip.

Before the operation

Your surgeon will plan the operation using X-rays and scans such as MRI or ultrasound. These show the shape of your hip socket and the condition of the joint surface, so they are usually done before surgery is booked.

In the weeks before the operation, you will be given clear instructions. You will need to stop eating and drinking seven hours before surgery. This longer gap means your operation can be brought forward if the theatre list runs early. Some medications may need to be paused, so bring a list of everything you take and your surgeon will advise which ones to stop. Arrange for someone to drive you home afterwards, and wear loose, comfortable clothing on the day. If you have other medical conditions, you may need blood tests or a review with the anaesthetist.

On the day

You arrive at the hospital's surgical admissions unit, where you are checked in and prepared for theatre. You will meet the anaesthetist, a doctor who looks after your anaesthetic and pain relief during and after the operation. This operation is done under general anaesthetic. A regional nerve block is sometimes added for post-operative pain relief; the anaesthetist will discuss this with you on the day.

You are then taken into the operating theatre, where the operation is performed. When it is finished, you wake up in the recovery area. Nurses there watch over you while the anaesthetic wears off. Once you are stable, you either move to a ward or go home, depending on the procedure and how your recovery is going.

What the operation involves

Periacetabular osteotomy is an operation on the pelvis. The surgeon makes a cut at the front of your hip, along the line where the skin creases naturally. Through this cut, the surgeon reaches the bone around your hip socket.

The surgeon then cuts the bone around the socket in several places, leaving one strong column of bone intact. This lets the whole socket move as one piece. The surgeon turns the socket so it sits over more of the ball of your hip joint, giving it better cover. Once the socket is in the new position, it is held there with screws while the bone heals.

If you also have damage inside the joint, such as a torn rim of cartilage or some extra bone at the top of the thigh bone, the surgeon can deal with this at the same time. The hip joint can be looked at with a camera through a small cut, and any rough areas on the thigh bone can be smoothed. Doing this in the same operation means one anaesthetic and one recovery.

The cut is closed with stitches and covered with a dressing. The whole operation usually takes a few hours.

Some people need more than one operation on their hip over time. If you have had hip surgery before, the socket may not be able to be turned as far, and the risk of problems is higher. Your surgeon will talk this through with you before you decide.

After the operation

You will wake up in the recovery area, then move to the ward or go home once you are stable. Your team will tell you whether you go home the same day or stay one night in hospital. Nurses will keep an eye on you and give you pain relief as needed. Someone should stay with you for the first 24 hours after you get home. Your hip will be covered with a dressing over the stitches. We leave the dressing on for about 10 days; please do not take it off before then unless we tell you to. We change or remove it when we see you. A physiotherapist may help you stand and take a few steps, sometimes with a walking aid. You will not need a brace after this operation.

Recovery

The first days are the hardest. Your hip will ache and the area around the cut will be swollen and bruised. Pain relief keeps this comfortable, and the discomfort eases a little more each day as the swelling settles. Rest, ice and keeping your leg in a comfortable position all help.

You will start moving early. A physiotherapist will guide you through simple exercises to keep your hip from getting stiff, and you will walk with a walking aid at first. You will not need a brace. You can move around the house and do light tasks, but you should not twist, bend deeply or put full weight through the hip until your team says it is safe. Sleeping on your back may feel easiest while the cut heals.

As the weeks pass, the swelling goes down and walking gets easier. Once your surgeon is happy the bone is healing, you will move from the walking aid to walking on your own, then build up your distances. When your surgeon clears you to drive, you can get back behind the wheel. Sport comes back in stages: low-impact activity first, then higher-impact sport as your strength and movement return. Most people who were active before surgery get back to their previous activity level or higher.

Recovery varies from person to person. Your timeline may differ, and your surgeon and physiotherapist will guide you at each step.

What can go wrong

Most patients do well, but problems can occasionally happen. Your surgeon and the team monitor you closely to spot any issue early.

The bone that has been cut needs to knit together, and this takes time. If a cut site is slow to heal or does not heal, you may feel a deep ache or a sharp pain in the groin or buttock that does not settle. Sometimes a small crack appears in the pelvis from extra load on the healing bone. Tell your team at review if pain lingers or worsens; you may need more scans, and a small number of people need another operation to help the bone heal.

The nerves near the hip can be irritated during surgery. You might notice numbness or tingling down the outer thigh, or weakness lifting your foot. These effects are usually temporary and settle on their own. Mention any new numbness, pins and needles or weakness at your next review, or sooner if it is severe.

The cut can become infected. Watch for redness that spreads out from the wound, warmth, increasing pain, weeping fluid or a fever. Most wound infections settle with antibiotics. If the wound looks worse or you feel unwell, call the clinic promptly; some infections need a return to theatre for the wound to be washed out.

A fall in the early weeks can shift the bone before it has healed. If you fall and your pain suddenly changes, contact the clinic straight away.

The screws holding the socket can occasionally irritate nearby tissue. If a screw causes a nagging ache or a sharp poke near the front of your hip, bring it up at review; sometimes a screw is removed later.

Rarely, a weakness in the abdominal wall near the scar can allow a bulge to appear, especially with coughing or straining. If you notice a new bulge, see your GP.

If you become pregnant later, a caesarean birth may be more likely. Discuss this with your obstetrician when the time comes.

The complications table on this page lists typical rates if you want the specifics.

When to call us

Most problems show up early, and we would rather hear about them sooner than later. Call us if you have a fever, if the redness around your wound is spreading, or if the wound starts weeping fluid. Call us if your pain suddenly gets worse or does not settle with pain relief. Go to emergency if you have swelling or pain in your calf, or shortness of breath, as these can be signs of a blood clot. Go to emergency if you lose feeling in your leg or cannot move it. If you fall and your pain changes, call us straight away.

Reviewed by AI synthesis (v2) — pending human review · 9 September 2026.

Want the clinical detail? Read the clinician version.

Talk to your treating clinician for advice specific to you.

For an appointment with the CQ Hand + Upper Limb team, ask your GP about a referral or visit www.cqupperlimb.com.

Evidence & references

This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Anatomy & Pathophysiology

Surgical Approach & Biomechanics

  • Periacetabular osteotomy (PAO) was described by Ganz and others in the 1980s as a method for stabilizing symptomatic dysplastic hips in skeletally mature patients [16].
  • The goal of PAO is to prevent arthritic deterioration in symptomatic dysplastic hips [16].
  • The osteotomy is performed through a Smith-Petersen approach [16].
  • The Smith-Petersen approach allows for reproducible bony cuts and extensive rotational freedom for acetabular repositioning [16].
  • The Smith-Petersen approach carries little risk of osteonecrosis of the acetabular segment [16].
  • The labrum and anterior femoral head-neck junction can be accessed through the distal end of the Smith-Petersen approach via arthrotomy [16].
  • The rotated acetabular fragment is stabilized with screw fixation [16].
  • Patients can be mobilized relatively quickly after PAO because the posterior column is left in continuity [16].
  • Leaving the posterior column in continuity keeps the ischium attached to the axial skeleton [16].

Indications & Pathological Criteria

  • PAO is indicated for symptomatic younger patients with spherically congruent dysplasia of the hip [16].
  • A lateral center edge (LCE) angle of less than 20 degrees is an indication for PAO in symptomatic younger patients [16].
  • Minimal or no secondary arthritic changes (Tönnis grade 0 or 1) are required for PAO indication in symptomatic younger patients [16].
  • Symptomatic patients with weight-bearing or activity-related pain and center edge angles between 20 and 25 degrees may be reasonable surgical candidates for PAO [16].
  • Women with coxa valga and excessive anteversion are specifically noted as potential candidates for PAO with center edge angles between 20 and 25 degrees [16].
  • Adolescent patients with hip dysplasia who have fair congruity may be considered for PAO [16].
  • Adolescent patients with hip dysplasia tend to fare better than older patients [16].
  • PAO in adolescent patients may delay the need for hip replacement for one to two decades [16].
  • Preoperative age older than 35 is an independent factor predictive of PAO failure [16].
  • Fair or poor joint congruence is an independent factor predictive of PAO failure [16].
  • When preoperative age is older than 35 and joint congruence is fair or poor, the chance of resultant severe pain or conversion to total hip replacement reaches 95% [16].
  • Patients older than 50 years of age have radiographic and clinical 2-year results similar to those in patients younger than 50 years of age [16].
  • PAO can be indicated for patients older than 40 years with a spherical femoral head and minimal arthritic change [16].
  • Pincer-type femoroacetabular impingement (FAI) with global acetabular retroversion is an indication for PAO [16].

Associated Femoral Pathology & Osteotomies

  • Intertrochanteric osteotomy of the proximal femur is occasionally performed as a simultaneous procedure with PAO [16].
  • Varus derotational osteotomy is performed to correct excessive valgus and anteversion of the proximal femur [16].
  • Valgus osteotomy can be performed for coxa vara [16].
  • Valgus osteotomy can be performed for aspherical Perthes type femoral head deformity to maintain articular congruence [16].
  • Valgus osteotomy is used to avoid impingement of the greater trochanter with the rotated acetabular rim [16].
  • Relative neck lengthening with osteochondroplasty of the femoral neck through open surgical dislocation combined with PAO has reported good short-term benefits in patients with typical Perthes deformity [16].

Complications & Risk Factors

  • In a multicenter study of 1760 periacetabular osteotomies, the incidence of sciatic or femoral nerve partial or complete palsy was 2.1% [17].
  • Half of the sciatic or femoral nerve palsies following PAO recovered fully [17].
  • Recovery from nerve palsy following PAO was more likely when the femoral nerve was involved [17].
  • Complications following PAO include superficial and deep infection [17].
  • Heterotopic ossification is a reported complication following PAO, though it is rarely symptomatic [17].
  • Acetabular fragment migration requiring reoperation is a reported complication following PAO [17].
  • Symptomatic hardware requiring removal is a reported complication following PAO [17].
  • The rate of symptomatic thromboembolic events following PAO is approximately 1% using a variety of thromboprophylactic measures [17].
  • Obesity raises the risk of complications following PAO by a factor of 10 [17].
  • Larger blood loss is associated with a higher rate of perioperative complications following PAO [17].
  • Longer surgery duration is associated with a higher rate of perioperative complications following PAO [17].
  • Associated femoral osteotomy is associated with a higher rate of perioperative complications following PAO [17].

Combined Arthroscopic Procedures

  • Arthroscopy of the central compartment to treat labrochondral pathology at the same time as PAO has been reported [17].
  • Short follow-up of combined arthroscopy and PAO does not demonstrate complication rates higher than PAO alone [17].
  • The use of arthroscopy for labral and chondral disorders due to dysplasia is controversial [17].
  • Some reports indicate that arthroscopic procedures for dysplasia create increased instability [17].
  • Patients with borderline dysplasia with impingement (LCE angle 20 to 24 degrees) fall between clear indications for PAO and arthroscopic FAI surgery [17].
  • At 26 months, Larson et al. found good to excellent results in 61% of patients with borderline dysplasia after labral repair or debridement [17].
  • In the study by Larson et al., associated femoral osteochondroplasty was performed in 72% of patients with borderline dysplasia [17].
  • In the study by Larson et al., capsular plication was performed in 82% of patients with borderline dysplasia [17].
  • Domb et al. reported good to excellent results in 77% of patients with borderline dysplasia (LCA ≥18 degrees and ≤25 degrees) at 2 years after arthroscopic labral repair with capsular plication with inferior shift [17].
  • Patients with borderline dysplasia are more likely to have higher grades of chondral damage on both the femoral head and acetabulum at the time of FAI arthroscopic surgery compared to patients without borderline dysplasia [17].
  • Greater degrees of acetabular chondral damage are predictors of poorer outcomes in patients with borderline dysplasia treated with arthroscopy [17].
  • Greater labral damage is a predictor of poorer outcomes in patients with borderline dysplasia treated with arthroscopy [17].
  • Lesser degrees of femoral head cartilage damage are predictors of poorer outcomes in patients with borderline dysplasia treated with arthroscopy [17].

Investigations

Radiography

  • Plain radiographs are the first imaging studies obtained for patients presenting with hip pain [6].
  • Standard AP radiographs of the hip and pelvis are used to examine bony architecture, check for evidence of joint space narrowing or changes to bone quality, and quantify femoral head coverage [6].
  • The Dunn view and frog leg view are appropriate to measure the alpha angle to determine the presence of impingement [6].
  • A complete hip series usually consists of an anterior-posterior (AP) pelvis, a centered AP hip, a lateral view (frog-leg, cross-table, Dunn 45° or 90°), and a false-profile (Lequesne) view [7].
  • Acetabular morphology is assessed on AP pelvis radiographs to evaluate acetabular overcoverage and undercoverage [7].
  • The femoral head-neck junction morphology is often assessed using the alpha angle [7].
  • Some studies have shown that radiographs, in particular the Dunn 45° view, may be more accurate for determining the alpha angle measurement than CT or MRI [7].
  • The Tönnis angle is defined by the angle of the acetabular sourcil and a line parallel to the transverse pelvis axis, with values between 0° and 10° considered normal [7].
  • The lateral center-edge angle of Wiberg is the angle between a line from the center of the femoral head perpendicular to the transverse pelvis axis and a second line from the center of the femoral head to the superolateral most point of the acetabulum, with angles of 20°–40° considered normal [7].
  • The femoral head extrusion index is defined by the length of the femoral head that lies beyond the acetabulum as a percentage of the total horizontal width of the femoral head, with values greater than 25% considered abnormal [7].
  • Coxa profunda is diagnosed when the fossa line touches or is medial to the ilioischial line on an AP pelvis radiograph [7].
  • The "crossover" sign on an AP pelvis radiograph indicates acetabular retroversion related to lateralization of the anterior acetabular wall relative to the posterior acetabular wall [7].
  • An optimal AP pelvis image requires the sacrococcygeal joint to be between 3 and 5 cm above the superior border of the symphysis pubis for neutral pelvic tilt [7].
  • Osteoarthritis of the hip can be categorized using the Kellgren-Lawrence or Tönnis classifications [7].
  • Radiographs remain integral to the assessment of fractures and can be supplemented with CT to further investigate suspected occult fractures, define fracture morphology, and assist in preoperative planning [7].

Magnetic Resonance Imaging

  • MRI is the modality of choice for patients suspected of soft tissue or intra-articular pathology, given its superior sensitivity and specificity [6].
  • Conventional MRI is effective at identifying osteochondral injuries, musculotendinous pathologies, and inflammation [6].
  • Magnetic resonance arthrography (MRA) is more appropriate than conventional MRI to determine injuries to the labrochondral structures and the ligamentum teres and to identify the presence of loose bodies and synovial chondromatosis [6].
  • The utility of MRA in the accurate detection and staging of articular cartilage lesions is reduced, with sensitivity reported to be less than 50% compared with arthroscopic findings [6].
  • Recent advances in MRI imaging techniques, such as delayed gadolinium-enhanced MR imaging and T2* mapping, allow for a more in-depth analysis of the structure of articular cartilage [6].
  • Delayed gadolinium-enhanced MR imaging and T2* mapping were effective at detecting early changes to the articular cartilage surfaces of patients with hip dysplasia and femoroacetabular impingement [6].
  • Noncontrast MRI at 3T is generally adequate for diagnosing intra-articular pathology [10].
  • If 3T imaging is unavailable, MRA can be considered at 1.5T for increased diagnostic accuracy [10].
  • MRI is helpful in identifying femoral neck stress fracture in athletes and predicting patients that may require surgical intervention [10].
  • MRI is useful for the assessment of DDH and FAI, as well as for extra-articular pathologies, stress injuries of bone, and hip arthroplasties [10].
  • MRI is helpful in assessing complications of conventional and resurfacing hip arthroplasties, particularly those with metal-on-metal bearing systems [10].
  • Major MRI findings that help predict histologic ALVAL scores include synovial thickening, synovitis, synovial volume, abductor disruption, and soft-tissue edema [10].
  • A prospective study found similar accuracies between noncontrast 3T MRI and 1.5T MRA in femoroacetabular impingement [8].
  • In a retrospective study evaluating noncontrast 3T MRI versus hip arthroscopy, accuracy for labral tears was 98% and for acetabular cartilage lesions was 90% [8].

Computed Tomography

  • CT scans are effective for examining cortical and cancellous bone and can be used to create three-dimensional reconstructions of the hip for use in surgical planning [6].
  • Measurements of femoral head coverage and acetabular and femoral impingement can be performed reliably using CT images [6].
  • CT overcomes the limitations of radiography by providing three-dimensional assessment of bony morphology and, to some degree, assessment of soft-tissue abnormalities [2].
  • Combined with arthrography, CT can evaluate chondrolabral abnormalities, specifically in patients with contraindications to MRI [2].
  • CT is helpful in fracture evaluation, particularly in the setting of negative radiographs or for further defining fracture morphology in patients requiring surgical reduction [2].
  • Low-dose CT with three-dimensional reformats is particularly useful in surgical planning of complex or borderline deformities [12].
  • 3D volume renderings from CT are useful to aid in preoperative planning in FAI and subspine impingement [10].

Ultrasonography

  • Ultrasonography provides real-time dynamic assessment of the hip and is useful in diagnosing soft-tissue abnormalities about the hip joint [2].
  • Ultrasonography is particularly useful in providing real-time guidance during diagnostic and therapeutic procedures [2].
  • Although ultrasonography is a valuable tool to examine pediatric hip conditions, its utility in evaluating the adult hip is limited [6].
  • Ultrasonography can be an effective modality to identify musculotendinous disruptions, effusions associated with intra-articular pathology, or inflammatory conditions, such as bursitis [6].
  • Ultrasonography is increasingly used for targeted injections into muscles, tendons, or intra-articularly around the hip for use with corticosteroids or biologic treatments [6].
  • Ultrasonography allows bedside evaluation of the hip and can be used to guide interventions in the office setting [10].
  • Ultrasonography cannot image inside bone because bone cortex reflects almost all sound waves [11].
  • Internal joint structures are not well visualized by ultrasonography unless they are in a superficial location [11].
  • Image quality and interpretation of ultrasonography depend on the experience of the ultrasonography technician and the radiologist [11].

General Principles

  • A thorough understanding of normal anatomy and biomechanics is necessary to identify pathology and determine the appropriate course of treatment [1].
  • Findings from imaging studies should complement clinical examination findings to provide the most accurate diagnosis [1].
  • Clinical examination tests and imaging findings should be used to confirm a suspected clinical diagnosis [1].

References

[1] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy and Biomechanics, Evaluation, Clinical Examination, and Imaging of the Hip > Summary.

[2] Orthopaedic Knowledge Update Sports Medicine 6. Imaging of the Hip > Introduction.

[6] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy and Biomechanics, Evaluation, Clinical Examination, and Imaging of the Hip > Imaging.

[7] Orthopaedic Knowledge Update Sports Medicine 6. Imaging of the Hip > Radiography.

[8] Orthopaedic Knowledge Update Sports Medicine 6. Imaging of the Hip > Annotated References.

[10] Orthopaedic Knowledge Update Sports Medicine 6. Imaging of the Hip > Summary.

[11] Aaos Comprehensive Orthopaedic Review 3. Musculoskeletal Imaging* > IV. Ultrasonography.

[12] Aaos Comprehensive Orthopaedic Review 3. Nonarthroplasty Surgical Treatment of the Hip > I. Femoroacetabular Impingement.

[16] Campbell S Operative Orthopaedics 4 Volume Set. COMBINED HIP ARTHROSCOPY AND LIMITED OPEN OSTEochondroplasty > PERIACETABULAR OSTEOTOMY.

[17] Campbell S Operative Orthopaedics 4 Volume Set. COMBINED HIP ARTHROSCOPY AND LIMITED OPEN OSTEochondroplasty > COMPLICATIONS FOLLOWING PERIACETABULAR OSTEOTOMY.

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a. UNLESS OTHERWISE SEPARATELY UNDERTAKEN BY THE LICENSOR, TO THE EXTENT POSSIBLE, THE LICENSOR OFFERS THE LICENSED MATERIAL AS-IS AND AS-AVAILABLE, AND MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND CONCERNING THE LICENSED MATERIAL, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHER. THIS INCLUDES, WITHOUT LIMITATION, WARRANTIES OF TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT, ABSENCE OF LATENT OR OTHER DEFECTS, ACCURACY, OR THE PRESENCE OR ABSENCE OF ERRORS, WHETHER OR NOT KNOWN OR DISCOVERABLE. WHERE DISCLAIMERS OF WARRANTIES ARE NOT ALLOWED IN FULL OR IN PART, THIS DISCLAIMER MAY NOT APPLY TO YOU.

b. TO THE EXTENT POSSIBLE, IN NO EVENT WILL THE LICENSOR BE LIABLE TO YOU ON ANY LEGAL THEORY (INCLUDING, WITHOUT LIMITATION, NEGLIGENCE) OR OTHERWISE FOR ANY DIRECT, SPECIAL, INDIRECT, INCIDENTAL, CONSEQUENTIAL, PUNITIVE, EXEMPLARY, OR OTHER LOSSES, COSTS, EXPENSES, OR DAMAGES ARISING OUT OF THIS PUBLIC LICENSE OR USE OF THE LICENSED MATERIAL, EVEN IF THE LICENSOR HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH LOSSES, COSTS, EXPENSES, OR DAMAGES. WHERE A LIMITATION OF LIABILITY IS NOT ALLOWED IN FULL OR IN PART, THIS LIMITATION MAY NOT APPLY TO YOU.

c. The disclaimer of warranties and limitation of liability provided above shall be interpreted in a manner that, to the extent possible, most closely approximates an absolute disclaimer and waiver of all liability.

Section 6 -- Term and Termination.

a. This Public License applies for the term of the Copyright and Similar Rights licensed here. However, if You fail to comply with this Public License, then Your rights under this Public License terminate automatically.

b. Where Your right to use the Licensed Material has terminated under Section 6(a), it reinstates:

1. automatically as of the date the violation is cured, provided it is cured within 30 days of Your discovery of the violation; or

2. upon express reinstatement by the Licensor.

For the avoidance of doubt, this Section 6(b) does not affect any right the Licensor may have to seek remedies for Your violations of this Public License.

c. For the avoidance of doubt, the Licensor may also offer the Licensed Material under separate terms or conditions or stop distributing the Licensed Material at any time; however, doing so will not terminate this Public License.

d. Sections 1, 5, 6, 7, and 8 survive termination of this Public License.

Section 7 -- Other Terms and Conditions.

a. The Licensor shall not be bound by any additional or different terms or conditions communicated by You unless expressly agreed.

b. Any arrangements, understandings, or agreements regarding the Licensed Material not stated herein are separate from and independent of the terms and conditions of this Public License.

Section 8 -- Interpretation.

a. For the avoidance of doubt, this Public License does not, and shall not be interpreted to, reduce, limit, restrict, or impose conditions on any use of the Licensed Material that could lawfully be made without permission under this Public License.

b. To the extent possible, if any provision of this Public License is deemed unenforceable, it shall be automatically reformed to the minimum extent necessary to make it enforceable. If the provision cannot be reformed, it shall be severed from this Public License without affecting the enforceability of the remaining terms and conditions.

c. No term or condition of this Public License will be waived and no failure to comply consented to unless expressly agreed to by the Licensor.

d. Nothing in this Public License constitutes or may be interpreted as a limitation upon, or waiver of, any privileges and immunities that apply to the Licensor or You, including from the legal processes of any jurisdiction or authority.

Creative Commons is not a party to its public licenses. Notwithstanding, Creative Commons may elect to apply one of its public licenses to material it publishes and in those instances will be considered the “Licensor.” The text of the Creative Commons public licenses is dedicated to the public domain under the CC0 Public Domain Dedication. Except for the limited purpose of indicating that material is shared under a Creative Commons public license or as otherwise permitted by the Creative Commons policies published at creativecommons.org/policies, Creative Commons does not authorize the use of the trademark "Creative Commons" or any other trademark or logo of Creative Commons without its prior written consent including, without limitation, in connection with any unauthorized modifications to any of its public licenses or any other arrangements, understandings, or agreements concerning use of licensed material. For the avoidance of doubt, this paragraph does not form part of the public licenses.

Creative Commons may be contacted at creativecommons.org.