Robotic hip replacement, from the surgeon who brought it to Hawai‘i

Robotic hip replacement is a total hip replacement planned in three dimensions from a CT scan of your own hip, then carried out with a robotic arm that holds that plan while the surgeon works — confirming cup position, implant sizes, leg length, and offset within millimeters. It suits nearly every first-time hip. In Honolulu, Dr. Paul Norio Morton — who performed Hawai‘i's first robotic hip replacement in 2022 — uses robotic assistance on every hip at Pacific Bone & Joint, through the muscle-sparing anterior approach. On Hawai‘i Island, Mako robotic hip replacement is now done at Hilo Community Surgery Center. Most patients walk the day of surgery. Individual results vary.

Robotic hip replacement starts weeks before the operating room. A CT scan of your pelvis and hip is converted into a three-dimensional model of your own anatomy, and on that model Dr. Morton plans the operation in advance: cup size and position — inclination and anteversion — stem size, leg length, and offset, set to your bone rather than a population average. On surgery day your anatomy is registered to that plan, and the robotic arm keeps reaming and cup impaction inside it while leg length and offset are displayed live. If your anatomy calls for an adjustment mid-case, the plan changes with it and the arm holds the new one.

One thing the robot does not do is operate. It holds no scalpel and makes no decisions. Think of it as a GPS with guardrails: the surgeon performs every step, and the robot keeps the execution inside the plan — and confirms it before you ever leave the operating room.

In practical terms, robotic assistance adds:

• Patient-specific planning from your own CT — every cup and stem is sized and positioned for your hip before the first incision
• Improved accuracy of component positioning, with fewer outliers than manual instrumentation
• Measured leg length and offset — the two things patients most often notice after a hip replacement, verified on screen rather than estimated
• Haptic guidance — the arm holds the reamer and the cup inside the planned boundary, so the plan and the operation stay the same thing
• Flexibility — the plan can be adjusted during the operation when your anatomy calls for it
• Minimal added trauma — the robot works through the same muscle-sparing exposure, not a bigger one

Dr. Morton performed the first robotic-assisted total hip replacement in the state of Hawai‘i in 2022, using the ROSA® platform. Earlier that same year, he performed the first robotic joint replacement on Hawai‘i Island at Kona Community Hospital — a meaningful milestone for a surgeon raised in Kea‘au.

Those firsts weren't about novelty. They were the product of fellowship training in adult hip and knee reconstruction at the University of Chicago and a conviction that patients here deserve the same technology available at major mainland centers — without flying five hours to get it. Being first also meant building the protocols, training the operating room teams, and proving the workflow so that robotic assistance could become what it is in his practice today: routine, not exceptional, across O‘ahu and Hawai‘i Island. The newest chapter is Mako: CT-planned, haptic-guided robotic hip replacement at Hilo Community Surgery Center, so a Big Island patient can have a robotic hip on the Big Island.

Precision is not a luxury in hip replacement — it determines how the joint behaves for decades. A hip replacement done freehand by an experienced surgeon is usually positioned well; robotic guidance exists to close the gap between usually and always. Three things depend directly on component position:

• Stability. Cup orientation works together with the surgical approach, soft-tissue tension, and how your spine moves your pelvis — and Dr. Morton plans for all four in every hip. It is worth the effort at the front end: revision surgery for a dislocated hip is among the more disruptive and expensive outcomes to treat. Accurate cup placement, a muscle-sparing anterior approach and spine-aware planning are how that plan gets built.
• Leg length. A hip that leaves one leg noticeably longer is one of the most common sources of dissatisfaction after surgery — especially in Hawai‘i, where people live in slippers or walk barefoot on the beach and feel every millimeter of difference. Robotic tracking measures leg length in real time so it is restored, not guessed.
• Implant wear. Components that articulate at the intended angles distribute load evenly. Malposition concentrates stress and can accelerate wear — precision protects the 20-plus-year lifespan modern implants are capable of.

Traditional instruments estimate these targets by eye and feel, and experienced hands estimate well. Robotic guidance doesn't estimate — it measures. Measurement is what turns a good plan into a reproducible result, hip after hip.

The case for robotic assistance is measurement. Here is what the published record supports:

• More accurate, more reproducible cup position. In a matched-pair laboratory study of a CT-free robotic hip platform (Kamath et al., Journal of Robotic Surgery, 2021 — 33 hips per arm, performed by 14 high-volume surgeons), 100% of robotically placed cups landed within the stricter Callanan target zone versus 73% with manual instruments, with roughly a third of the inclination error.
• Fewer leg-length outliers. The same study, and a propensity-matched clinical series (Clement et al., Bone & Joint Research, 2021), found leg length restored to plan significantly more consistently with robotic guidance.
• Better early hip scores in several studies. A systematic review and meta-analysis of 17 studies (Ng et al., The Bone & Joint Journal, 2021) found more cups in the safe zone and a modestly better Harris Hip Score at short-to-mid-term follow-up; a 2016 cohort (Bukowski et al.) reported higher patient-reported scores at one year, and a Japanese series (Shibanuma et al., 2021) reported faster early walking versus navigated surgery.
• A stable hip is built from several things at once. A Mayo Clinic analysis (Abdel et al., Clin Orthop Relat Res, 2016) is why Dr. Morton personalizes the cup target rather than aiming at the classic safe zone alone. Registry analyses of 78,098 Swedish and 42,379 Finnish hip replacements (Hailer et al., 2012; Kostensalo et al., 2013) show that surgical approach, head size, and patient factors all shape how a hip behaves over the long run — which is why Dr. Morton pairs robotic planning with the anterior approach and spine-aware cup targeting rather than leaning on any single element.

Individual results vary.

Key sources: Kamath AF et al., J Robot Surg 2021 (PMID 34709535); Ng N et al., Bone Joint J 2021;103-B(6):1009-1020 (PMID 34058875); Clement ND et al., Bone Joint Res 2021;10(1):22-30 (PMID 33380216); Shibanuma N et al., BMC Musculoskelet Disord 2021;22:314 (PMID 33781263); Bukowski BR et al., Surg Technol Int 2016;29:303-308 (PMID 27728953); Hailer NP et al., Acta Orthop 2012 (PMID 23039167); Kostensalo I et al., Acta Orthop 2013 (PMID 23799348); Abdel MP et al., Clin Orthop Relat Res 2016 (PMID 26150264).

Dr. Morton — known to many patients as The Robot Doc — is certified on all four major robotic platforms: ROSA®, Mako, CORI, and VELYS. That breadth matters. Each system takes a different route to the same goal: some build the plan from a CT scan, others from X-rays or direct anatomic mapping, and each pairs with different implant families. Surgeons certified on a single system tend to fit every patient to that system; Dr. Morton can match the platform to your anatomy, your implant, and the hospital or surgery center where your operation takes place. The technology serves the plan, not the other way around.

On Hawai‘i Island, Mako is the hip platform. Robotic hip replacements at Hilo Community Surgery Center are Mako cases: the plan is built from a CT scan of your pelvis and hip, giving a fully volumetric, millimeter-accurate map of your anatomy, and the robotic arm then holds the reamer and the cup inside that plan. It is a natural fit for complex anatomy — a shallow socket, a deformed femur, prior surgery — and it means Big Island patients get a CT-planned robotic hip without a flight to O‘ahu. ROSA® reaches the same destination from standard X-rays and live anatomic mapping. Because Dr. Morton operates at The Queen's Medical Center, Adventist Health Castle, and Hilo Community Surgery Center, he can pair the right platform with the right venue for your case.

Nearly every first-time hip replacement can be done with robotic assistance — Dr. Morton uses it routinely rather than reserving it for select cases. Age is not a limiting factor; if anything, precision matters most in the youngest patients, whose implants have the most miles ahead of them (see am I too young for hip replacement?). Robotic planning earns its keep when anatomy is less forgiving: a dysplastic (shallow) socket, a collapsed femoral head from avascular necrosis, a stiff spine that changes how the pelvis tilts, or prior surgery around the hip. Retained hardware, severe deformity, or major bone loss occasionally change the plan or the platform, and bone quality shapes fixation choices more than the decision to use the robot.

The real question is whether your hip is ready for replacement at all. Not sure where you stand? Book a consultation or call (808) 439-6201 to find out. You may be ready if you recognize yourself here:

Hip osteoarthritis is the most common culprit. Cartilage is the smooth protective surface on the ends of your bones that keeps them from rubbing together; osteoarthritis is the wear and tear of that cartilage. Once it wears away, bone grinds on bone — and basic activities like walking, sitting, even lying down can become painful.

Other causes include osteonecrosis (loss of blood supply to the femoral head, causing the bone to die), trauma, and rheumatoid arthritis.

Surgery is not the first step. Dr. Morton encourages patients to explore non-operative treatment strategies first — activity modification, physical therapy, medications, injections. When non-operative treatment has failed and the pain is dictating your life, that is when hip replacement earns its place.

Dr. Morton performs robotic hip replacement through the muscle-sparing direct anterior approach: a 3-to-6-inch incision at the front of the hip, directly over the joint, instead of the traditional 8-to-12-inch incision on the side. Because the front of the hip sits closer to the joint itself, the incision can be smaller — and more importantly, the approach follows the natural path between muscles rather than cutting through them or detaching them from bone.

That anatomical detail drives almost every recovery advantage:

• Less pain. With no muscle cut, many patients need little more than Tylenol for pain control after surgery.
• No posterior hip precautions. Traditional posterior approaches require patients to avoid internally rotating the hip or bending it past 90 degrees for weeks — no low chairs, no crossing your legs, careful getting in and out of cars. Anterior patients skip those restrictions entirely, which makes the recovery phase dramatically less limiting.
• Faster, easier recovery. Less pain plus no precautions means patients move confidently sooner — the foundation of Dr. Morton's rapid-recovery protocol.
• Early discharge. Many patients go home the day of surgery.
• Verified leg lengths. The face-up anterior position allows intraoperative X-ray verification, and robotic guidance stacks measurement on top of it.

The planning starts weeks before surgery, with imaging that turns your hip into something Dr. Morton can operate on before he operates on you.

A planning CT scan. For a Mako hip, a CT of your pelvis and hip is the foundation. It is quick and painless and needs no IV contrast, and software converts it into a three-dimensional model of your own anatomy — bone shape, socket depth, the deformity arthritis has left behind. On that model Dr. Morton sets cup size and position (inclination and anteversion), stem size, leg length, and offset before the day of surgery, so the operation begins with the decisions already made and checked.

Standing and sitting spine X-rays. These are taken whichever platform your case calls for, because they answer a question no CT can: how your pelvis tilts as you move. Arthritis of the spine changes that tilt between sitting and standing, which changes the functional orientation of your hip socket. A cup position that is textbook-perfect for one patient's spine can be wrong for another's. Understanding your specific pelvic-spine mechanics lets Dr. Morton personalize the target — not just hit a generic one.

Here is how a Mako robotic anterior hip replacement actually unfolds:

1. The plan, already built. Your CT-based 3D model comes into the room with cup size and position, stem size, leg length, and offset already set for your anatomy — the roadmap for the case.
2. Muscle-sparing exposure. The approach mirrors the standard anterior hip: superficially, the dissection passes between the sartorius and tensor fascia lata muscles; deeper, it travels between the rectus femoris and gluteus medius. No muscle is cut — which is why recovery is faster.
3. Registration. Tracking arrays, held by small pins, let the system match your actual anatomy to the CT model point by point, so the plan and your hip become the same thing. The pins are placed and removed within the same operation.
4. Haptic-guided reaming. Once the arthritic femoral head is removed, the socket is reamed with the robotic arm holding the reamer inside the planned boundary — depth and orientation stay where they were planned.
5. Controlled impaction. The cup is impacted while attached to the robotic arm, holding the planned inclination and anteversion — usually within the classic Lewinnek and Callanan target zones, and deliberately adjusted when your standing and sitting spine X-rays call for a different target.
6. Stem placement. The femoral stem is broached and sized by hand — surgical judgment and feel still matter, and the robot doesn't replace them.
7. Verification before closing. The system then displays two measurements conventional hip replacement can only estimate: leg length and offset. Offset is how far your femur sits from your pelvis — too much can tension the IT band and cause pain on the outside of the hip; too little can leave the hip unstable. Patients after traditional posterior hip replacement have long complained of exactly these two problems — a leg that feels longer and pain on the outside of the hip. Verifying both before the incision is closed is the point of the whole exercise, and it matters even more in revision and deformity surgery, where equal leg lengths are hardest to achieve.

Throughout, the plan is a starting point rather than a straitjacket: if your anatomy calls for a different cup angle, a different offset, or a different stem, Dr. Morton changes the plan and the arm holds the new one. Once the final implant is confirmed in position, you're on the road to recovery — with a hip placed using the most advanced technology and techniques available anywhere, right here in Hawai‘i.

Over 90% of people who have a total hip replacement experience a remarkable reduction in pain and a dramatic improvement in function. With normal use and activity, the plastic spacer in a modern hip replacement rarely wears out. But a replaced hip deserves long-term stewardship, and Dr. Morton builds that in:

• Annual surveillance. Dr. Morton follows every joint replacement patient with a yearly X-ray to confirm the implant is functioning at its best — for life. Small problems caught on a routine X-ray are simple; the same problems found late are not.
• Sensible activity. Increased weight or high-impact activity can accelerate wear on the plastic components and may cause the replacement to loosen or become painful. The American Academy of Orthopaedic Surgeons advises patients to avoid running, jogging, jumping, and other high-impact activities with a hip replacement. Nearly everything else — swimming, hiking, golf, cycling, surfing — is back on the table.

Most patients walk the day of surgery and many go home the same day through Dr. Morton's outpatient joint replacement pathway, with physical therapy available at his Honolulu and Kunia locations, or coordinated with a therapist near home for neighbor-island patients, working from Dr. Morton’s protocol. Individual results vary — the first year after hip replacement lays out the milestones.

Total hip replacement has a high success rate and is one of the most reliable operations in all of orthopedics. It is still major surgery, and honest counsel includes the risks:

• Blood clots — deep vein thrombosis or pulmonary embolism
• Blood loss that may require a transfusion
• Infection — one of the more serious complications, sometimes requiring multiple operations
• Implant loosening — occasionally requiring revision surgery
• Fracture — the implant changes how stress distributes across the bone, which can predispose to breaks
• Dislocation — when the ball pops out of the socket; addressed with accurate, verified cup placement, the muscle-sparing anterior approach, and spine-aware planning
• Leg-length inequality — minimized by measuring leg length during the operation rather than estimating it
• Heterotopic ossification — a rare complication in which the hip becomes increasingly stiff
• Nerve or blood vessel damage — extremely rare, but potentially serious

Dr. Morton takes great care to minimize every one of these risks and is happy to discuss any questions or concerns at your consultation — that conversation is part of the operation, not an afterthought.

Most patients who are candidates for total hip replacement are candidates for robotic assistance, and Dr. Morton uses it routinely rather than reserving it for select cases. It pairs naturally with the rest of his rapid-recovery protocol: anterior approach, opioid-sparing pain control, and same-day walking for most patients. Hawai‘i Island patients can have the whole thing at home — planning CT, Mako robotic hip replacement at Hilo Community Surgery Center, and follow-up in Hilo.

What happens next. Schedule an orthopedic consultation online or call (808) 439-6201. Pacific Bone & Joint sees patients in Honolulu (Ala Moana), West O‘ahu (Kunia), Hilo, and Kona. Bring a photo ID, your insurance card, and any prior X-rays or reports; managed-care and Medicaid/Quest plans may require a referral from your primary care physician, and the office can help you check (insurance plans accepted). When an in-person visit isn't practical, neighbor-island and mainland patients can start with a telehealth visit and existing X-rays — the 3D planning conversation travels well.