"Anterior total hip replacement has the fastest recovery."

There is no difference in recovery between the anterior and posterior approaches in THR. Neither is there any between hip resurfacing and THR. But there is a better final recovery with hip resurfacing. As discussed in the previous section, hip resurfacing patients regain more normal hip function.

My recovery protocol for both operations depends on the patient’s bone strength. All reasonably healthy people can have surgery as an outpatient at our surgery center. They go home or to a hotel within several hours after their surgery. They walk in the surgery center with crutches and learn to climb stairs. Costly hospitals filled with resistant bacteria and sick patients can be avoided altogether.

Narcotic medications are usually only needed for 3-4 days. Once patients are off these, they may resume driving and resume some remote work. Most people return to desk work in an office within 1-2 weeks. They may also resume upper body exercises including weightlifting. The only therapy required is a progressive walking program. Crutches for 1-2 weeks, cane for 1-2 weeks. Walking 1 mile without an assistive device in 6 weeks. Stairs are one leg at a time for 4 weeks, foot-over foot with the rail at 4-6 weeks. Most people still have a slight limp at 6 weeks, but none at 3 months. They no longer need a rail at 3 months. Walking more than a mile, swimming, golf exercise bike, elliptical, and light leg weightlifting is OK after 6 weeks. These light aerobic activities are continued until 6 months at which time full unrestricted activities are allowed including impact sports and heavy lifting.

Range of motion (ROM) is restricted past 90 degrees for 6 weeks. Full ROM is allowed after 6 months including kayaking, yoga, gymnastics, and ballet.

At 1 year, extreme activities such as contact sports, slide tackling in soccer, and rock climbing are approved.

People with weak bones require more restrictions in the first 6 months to prevent fracture but are also back to full activity by 6 months.

Many of the restrictions are required to allow adequate healing of the muscles and bone. The bone is weakened by surgery and returns to baseline by 6 months. Bone ingrowth into the implant is 90% complete by 6 months. The ligaments and muscles cut are also fairly well-healed by 6 months.

Most patients are better than pre-op by 6 weeks, 90% healed by 6 months, 95% healed by 1 year, and as good as they are going to get by 2 years.

In most patients near normal strength and ROM is achieved. Unless they have another limiting condition or are deconditioned, virtually all patients can return to their premorbid (before the hip arthritis became limiting) activity or sports activity including running 1-3 miles. Many, but not all patients desiring to return to distance running are able to do so. But some are limited to 1-3 miles due to residual discomfort with running.

I encourage full and unrestricted activity because, unlike THR, hip resurfacing does not fail with extreme use. The advantage of an anterior approach for THR is a faster operation and lower dislocation risk than posterior THR (but still higher than hip resurfacing). The disadvantage is a higher femoral fracture and infection rate. There is no difference in the recovery rate. Also, the function is no different for an anterior vs posterior THR, but THR has a lower final functional outcome than hip resurfacing.

The remaining question is whether hip resurfacing done through an anterior approach would lead to better ultimate function than one done through a posterior approach. This is not known. The only abnormal muscles we see after healing with a posterior approach are the 4 short external rotators (piriformis, obturator internus and externus and quadratus femoris). I detach these 4 muscles from the bone and repair them back to bone at the end of the operation. Nevertheless, they do not usually heal and function completely normally. But they are minor muscles in the hip and most people function at a very high level even though these are abnormal.

I do recommend exercises for these muscles after they have fully healed in 6 months. The other major muscles around the hip return to completely normal (as evidenced by anecdotal MRI comparison of both hips 1-year postop). Theoretically, an anterior approach avoids the rotators. But this is not exactly true either, because if you observe an anterior hip approach, the "tissue" at the posterior edge of the greater trochanter is released to allow the femur to be pulled out of the wound. This "tissue" is the rotator. They are not dissected off as completely as in a posterior approach, but they also are not repaired. Which is better? Nobody knows. It seems to be more difficult to perform a hip resurfacing through an anterior approach.

Many years ago an excellent surgeon I know reported a 9% intraoperative femoral neck fracture rate, and subsequently gave up resurfacing. There is now one recent publication of mid-term outcomes with anterior hip resurfacing and the implant survivorship is 93% @ 10 years. My implant survivorship currently is 99% @ 17 years. Clearly, at this point, durability is greater when done posteriorly. My suggested explanation is that the operation is so much more difficult from the front, that the surgeon has a much tougher time getting it right. But this is durability data.

What about function? How would we document the superior function of an anterior approach? Gait studies show normal fast gait with posterior resurfacing, so gait studies would be unhelpful. Maybe we could take a matched cohort of distance runners and see if one group is more likely to return to distance running after 1 year. Because the failure rate is so much lower with the posterior approach, and there is no clear evidence on function, I will stick with the posterior approach.