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Training and the Artificial Joint

by John Petrizzo, DPT, SSC | May 20, 2020

training with artificial joints

This article is intended to serve as a guide for those of you who may be considering having a joint replaced, are training with an artificial joint, or are responsible for the training of someone with an artificial joint.  My hope is that it will provide you with more insight into how the procedures are commonly performed, what to expect during the recovery period, and how you can successfully manage your training after a total joint replacement. 

The first thing we have to do is define what a total joint replacement actually is.  According to the American Academy of Orthopaedic Surgeons, a total joint replacement is a surgical procedure in which the parts of an arthritic or damaged joint are removed and replaced with a metal, plastic, or ceramic prosthesis which is designed to replicate the movement of a normal, healthy joint.  It is also common to see the procedure described as a “total joint arthroplasty.” 

Prevalence of Total Joint Replacement

You may be asking yourself right now, is total joint replacement really that common?  As a lifter or coach, do I really need to know about total joint replacement surgery?  In short, yes. As of 2010, 2.5 million Americans were living with a total hip replacement (1.4 million women and 1.1 million men), and an additional 4.7 million Americans were living with a total knee replacement (3.0 million women and 1.7 million men). Similarly, total shoulder replacement has increased by approximately 3,000 cases each year in the U.S. since 2004. This is compared to an annual increase of just 400 cases per year in the years prior. 

Trends indicate that we will continue to see a substantial rise in the prevalence of total joint replacement over time as well as a shift to younger people undergoing the procedure. In fact, utilization of total hip replacement is projected to grow by 174% between 2005 and 2030 and will continue to grow in the future due to the aging population and the obesity epidemic. 

The majority of people who undergo total joint replacement do so secondary to the development of osteoarthritis. In short, osteoarthritis is a condition in which the articular cartilage that lines the ends of our bones gradually erodes over time. The articular cartilage helps to distribute and disperse compressive forces to the underlying bone, and varies anywhere from 1-7 mm in thickness depending on the joint. Unfortunately for us, articular cartilage has a notoriously poor blood supply which also means that it has a relatively poor capacity to repair itself when damaged. What this means is that many of us will develop osteoarthritis in our joints to some extent as we age. The severity of the condition and whether or not it becomes symptomatic is dependent on a variety of individual factors.  

Osteoarthritis can develop in any joint in the body, although it more commonly develops in the hands, knees, hips, and spine. Osteoarthritis of the knee is the most commonly diagnosed form of the condition in the lower extremities. It is estimated that 6% of those aged 30 years and 15% of those aged 45 years have osteoarthritis of the knee and that nearly 45% of the adult population will develop osteoarthritis of the knee to some extent during their lifetime.  

Surgical History 

It may seem surprising, but total joint replacement has a history that spans over 100 years. The first attempts at hip and knee replacement occurred in Germany in the late 19th century when Professor Themistocles Gluck used ivory to replace the weight bearing surfaces of the hip and knee. Throughout the late 19th and early 20th centuries, surgeons experimented with placing various tissues such as pig bladders, submucosa, and even glass between the articulating surfaces of the arthritic hip. English surgeon George Mckee was the first to use a metal-on-metal prosthesis on a regular basis in the early 1950s. His prosthetic had a good survival rate but became unpopular in the 1970s due to the local effects of metal particles seen during revision surgery for prosthetic failure. 

Sir John Charnley is considered the father of modern hip replacement. The low-friction arthroplasty he designed in the early 1960s is identical in principle to the prostheses used today. It consisted of a metal femoral stem, a polyethylene (plastic) acetabular component, and acrylic bone cement which he borrowed from dentists. 

The “modern” era of total knee replacement began in 1954 with the launch of the first hinged prosthesis. Today, rotating-hinged prostheses allow for some rotation between the femoral and tibial implants which more closely approximates the normal motion between the joint surfaces. 

As the number of successful total joint replacements has increased over the past five decades, techniques have become more standardized and the average age of those undergoing the procedure has reduced. As a result, problems of implant failure due to wear of the weight bearing surfaces has been magnified. Thus, there are a variety of bearing options currently used in an attempt to find the combination that yields the fewest complications and the best long-term survival. 

Types of Prostheses 

Metal-on-polyethylene bearings are the most widely used of all the prostheses available today and are also the prostheses that we have the most follow-up data on. Whether you are undergoing a hip, knee, or shoulder replacement, the prosthesis that you receive will more than likely be comprised of a combination of metal and plastic (polyethylene). The main concern with this type of prosthesis is polyethylene debris which creates something called “peri-prosthetic osteolysis” which can damage the surrounding bone tissue and ultimately leads to implant failure. It is cited as the ultimate cause of most of the prosthetic failures that we see today. 

Metal-on-metal prostheses, while not widely used today, do offer several potential advantages when compared to the more common metal-on-polyethylene bearings. It has been reported that metal-on-metal prosthetic wear is 60 times less than expected with conventional metal-on-polyethylene prostheses for those with a total hip replacement. Additionally, in total hip replacement, the metal femoral heads are less brittle than other materials, thus they can have a larger diameter which increases joint stability and lowers the incidence of dislocation. Metal-on-metal implants also reduce osteolysis and peri-prosthetic inflammatory tissue compared to its polyethylene counterpart. 

However, an unknown quantity of metal-on-metal bearings is the long-term effects of liberated metal ions within the body. Cobalt and chromium ion blood levels have been reported to be 3-5x higher in those with a metal-on-metal prosthesis when compared to patients with a metal-on-polyethylene prosthesis. Carcinogenic risk exposure from these metal ions currently remains theoretical and there is currently insufficient clinical follow-up to draw firm conclusions about the ultimate safety of the new generation of metal-on-metal implants. According to the American Academy of Orthopaedic Surgeons, in 2011 the FDA ordered the manufacturers of metal-on-metal hip implant devices to further study the safety of these prostheses.   

Ceramic-on-ceramic prostheses were first introduced by the French surgeon Pierre Boutin in 1970. While not commonly used in the U.S. and U.K., approximately 50% of total hip replacements performed in central Europe use ceramic heads. The benefits of this type of prosthesis include their high level of hardness, scratch resistance, and maybe most importantly, the inert nature of their debris when compared to other implants. Unfortunately, these prostheses are costly, which is why they tend to be used less frequently than their metal-on-polyethylene counterparts.  

The Procedures: Hip 

There are several different ways in which a surgeon can perform a total hip replacement. The two most common approaches to this procedure that I see in my practice are the posterolateral approach and the anterior approach. Currently, there is still debate as to which of these options results in the best outcomes and lowest rates of complications. My experience has been that this is largely based on surgeon preference more so than any significant difference in surgical outcomes. 

The posterolateral approach gains access to the hip joint by splitting the gluteus maximus muscle, retracting the hip abductors, and then releasing the deep external rotators of the hip. The femur is then dislocated posteriorly in order for the proximal femur and acetabulum to be prepped for placement of the prosthesis. A potential disadvantage of this approach, particularly for lifters, is that for a period of time post-operatively, patients are typically placed on “hip precautions” to minimize the likelihood of the patient suffering a posterior hip dislocation. The precautions commonly prescribed following the procedure are no hip flexion beyond 90 degrees, no hip adduction past midline, and no hip internal rotation past neutral.  The amount of time that these precautions must be followed will vary depending on the surgeon’s preference. 

From a practical perspective, if you are someone who is returning to training following this type of procedure, it is important to build back your range of motion on the squat and deadlift gradually and to make sure that you are emphasizing shoving your knees out in order to avoid internal rotation and adduction of the hip during those movements. 

For the squat, I generally start people back with a partial range of motion box squat and gradually increase the range of motion over a period of several weeks.  Fellow Starting Strength Coach Andy Baker has a good video on how to progress squat range of motion for the elderly or detrained that you can check out here.

In the case of the deadlift, my preference would be to start with rack pulls or block pulls and then slowly work the bar down to the floor over the course of a few sessions. If you lack the equipment to perform rack pulls or block pulls, then a partial range of motion RDL could suffice. The only issue I have with the RDL is that it is harder to quantify the range of motion from rep to rep and from session to session in the same way that you can with the rack pull or block pull. 

Finally, I always recommend getting a copy of the surgical report for those that have undergone a posterolateral hip replacement, as I think it is important to know whether or not the deep external rotators of the hip were reattached following their release. I find that is the case for most of my patients, but not always. 

Another commonly performed approach to total hip replacement is the anterior approach.  Generally, this approach gains access to the hip joint either through the interval between the tensor fascia lata and gluteus medius or the interval between the tensor fascia lata and the sartorius. The potential benefits to a lifter from this type of procedure are that there is less overall tissue damage than the posterolateral approach and a decreased likelihood of suffering a posterior dislocation postoperatively. A potential negative of this procedure is that the surgeon may not have the same access to the joint that they do using the posterolateral approach and obese patients or those with increased soft tissue mass around the anterior hip may not be suitable candidates for this option. Additionally, depending on how the joint is accessed, a portion of the gluteus medius may need to be released from the greater trochanter, which can result in hip abductor weakness and an antalgic gait for a period of time following surgery.

It is important to note that the overwhelming majority of patients who undergo total hip replacement surgery have excellent recoveries regardless of which approach is used.  If you are a candidate for a hip replacement, it is important to discuss your options with a surgeon you are comfortable with, and come up with a plan for your surgery and recovery that you feel is best for you. 

total hip replacment x-ray (source: NIH)

Figure 1. An x-ray of a femoral prosthetic following hip replacement.

The Procedures: Knee 

Similar to total hip replacement, there are several surgical approaches that can be used to perform a total knee replacement. Depending on the type of prosthesis used, the posterior cruciate ligament is either maintained, sacrificed, or replaced with a polyethylene post. Similarly, if the patellofemoral joint is also arthritic, the patella can be resurfaced as well. However despite these possible variations in how the procedure is performed or the type of prosthetic used, the differences between these approaches are not as significant as those seen with total hip replacement and do not have a large impact on how rehab is approached postoperatively. 

Regardless of the approach used, the overwhelming majority of knee replacement surgeries involve replacing the damaged cartilaginous surfaces of the distal femur with a metal shell while the surface of the proximal tibia is most commonly replaced with polyethylene. 

Unlike the posterolateral hip replacement, there generally are no restrictions on patients following a total knee replacement. However, that does not mean that it is an easy recovery. Most patients find recovery from total knee replacements to be tougher than that of total hip replacement surgery. The primary reason for this is that the knee is often swollen and painful following the procedure. 

Additionally, the early phase of the rehab focuses on regaining range of motion in the knee which can be a painful process for many. I generally start people back using the leg press as most patients will not be able to squat to depth immediately after the surgery, and will also tend to compensate significantly while squatting by leaning towards their non-operative side. If you are curious as to how to best utilize the leg press for the goal of getting back to squatting, check out this video.

total knee replacement coronal and sagittal views

Figure 2. Coronal and sagittal x-rays of a knee prosthetic following total knee replacement.

For more information on the topic of hip and knee replacement surgery, see Starting Strength Radio #46.

What About the Shoulder? 

There are two different types of procedures offered to patients in need of a total shoulder replacement.  An anatomic total shoulder replacement, similar to knee and hip replacement, replaces the joint surfaces, but maintains the original anatomy of the joint and is frequently prescribed for patients with symptomatic degeneration of their glenohumeral joint who have an intact rotator cuff and maintained glenoid. An alternative procedure often used following failed anatomic replacement or in cases where the rotator cuff is no longer intact is referred to as Reverse Total Shoulder Replacement. In this procedure, the proximal humerus, which has a convex surface (the “ball”), is replaced with a concave prosthetic while the glenoid fossa of the scapula, which has a concave surface (the “socket”), is replaced with a convex prosthetic.  This procedure reverses the original anatomy in an attempt to increase joint stability in patients who lack the stability normally provided by the rotator cuff musculature.  Overall, complications occur in about 10% of anatomic shoulder replacements while complications from reverse total shoulder replacements have been reported as being significantly higher. 

One of the primary differences between the rehabilitation of the shoulder following a total shoulder replacement, as opposed to that of the hip and knee, is that you have to be more conservative with loading in the days and weeks immediately following the procedure. Most patients will be instructed to wear a sling for up to six weeks following surgery and initial rehab consists primarily of gentle range of motion exercises and submaximal isometric work for the surrounding musculature. I actually think that Rip’s shoulder rehab protocol detailed here, while not originally intended for patients who have undergone total shoulder replacement, actually is an excellent protocol for those looking to get back to training following these kinds of procedures, as it will help to restore range of motion and strength in a gradual and progressive manner more effectively than traditional physical therapy treatment.

shoulder prosthesis xray (Source: Lucien Monfils)

Figure 3. An x-ray of the glenohumeral component of an anatomic shoulder replacement.

Other Surgical Options 

Although not new, unicompartmental knee replacement is an alternative to total knee replacement for those with osteoarthritis on just one side of their knee. Unicompartmental knee replacement allows for preservation of bone tissue and offers patients a less invasive procedure with a faster recovery time. Good clinical results have been seen at more than 10 years post-op with prosthetic survival having been recorded at greater than 95%.

Similarly, hip resurfacing is an alternative to total hip replacement in young active patients because it spares much of the proximal femoral anatomy. Hip resurfacing first rose to prominence in the 1990s, but the prevalence of the procedure declined after several prosthetic designs were found to have unfavorable short-term results. Specific risk factors for early failure were found to include a small femoral head size, a diagnosis of avascular necrosis or dysplasia, female sex, and surgeon inexperience.  Data suggests that the ideal patient for this procedure is a male aged younger than 55 with a diagnosis of osteoarthritis. While the number of total hip resurfacing procedures has fallen in recent years, the number performed in patients aged younger than 55 with osteoarthritis rose in 2016. Direct comparisons to total hip replacement in the same demographic show similar prosthetic survivorship, clinical results, and complication rates. 

coronal and sagittal xrays unicompartmental knee replacement

total hip replacement vs resurfacing

Figure 4. Coronal and sagittal x-rays of a unicompartmental knee replacement (top) and a comparison between a resurfaced hip and a hip that has undergone a total replacement (bottom).

How Does Total Joint Replacement Impact Training? 

In short, we don’t know. A recent survey study found that only 20% of patients who underwent total hip replacement participated in “strenuous sports” regularly or frequently after surgery. However, it is important to note that sports participation was strongly correlated with motivation, not level of discomfort. 

Longitudinal research has shown a mild increase in physical activity in patients following total hip replacement, but a similar decrease in physical activity following total knee replacement. Additionally, numerous studies have found that total joint replacement alters joint biomechanics and loading patterns during activities of daily living. However, there is also evidence that these altered mechanics may be present secondary to compensatory strategies that were learned prior to surgery and not necessarily as a result of the surgery itself. 

Similarly, multiple researchers have found that the surrounding musculature following total joint replacement often remains weaker when compared to both aged-matched controls and the non-operative limb. This observation still persists even after several years and can be problematic as it has been found that subjects with weak knee extensor musculature apply greater load to the knee joint during the gait cycle when compared to subjects with stronger knee musculature. 

Unfortunately, there is very limited research examining the impact that progressive resistance training has on total joint replacements. Limited, short-term research has shown that commencing a RT protocol utilizing the leg press and leg extension at 10RM loads as soon as 1-2 days post-op had a positive impact on knee extension strength and walking speed without increasing knee joint effusion or pain. However, a larger follow-up study did not show statistically significant differences in objective or subjective outcome measures between resistance training group and traditional rehabilitation. 

Summary of Current Evidence 

I feel that the following statements accurately summarize the current state of the evidence as it relates to total joint replacement: 

  • The optimum bearing surface and approach used for hip replacement remains debatable.  Long-term follow up comparing survivorship, functional outcomes, and radiologic outcomes between different bearing surfaces and procedures used has largely been equivocal to this point.
  • Hip resurfacing and unicompartmental knee replacement both appear to be safe and effective surgical options for younger patients with osteoarthritis as they have been shown to have a similar survivorship to total joint replacement.
  • Reverse total shoulder replacement has exponentially increased the number of patients who are able to undergo shoulder replacement, but has been shown to have increased complication rates when compared to anatomic total shoulder replacement.
  • Total joint replacement has been shown to have a negligible impact on post-op physical activity, and return to more strenuous activities appears to be related more to patient’s own motivation rather than level of discomfort.
  • Research examining the impact of resistance training on total joint replacement is very limited at this time, as there is a lack of long-term studies.

Where Do We Go From Here? 

Despite the lack of research evidence to support the use of resistance training to facilitate recovery following total joint replacement, we do know the myriad of benefits that resistance training has on the body as a whole. I would also add that at this time, there is nothing currently in the literature that would suggest resistance training poses any acute risk to patients following a total joint replacement. 

Our joints deal with large compressive loads repetitively throughout our daily lives, and I see no reason why a properly implemented resistance training protocol cannot be a safe and effective way to improve one’s health and function following a total joint replacement. However, due to the lack of evidence to supports its use, I can only suggest implementing resistance training with patients and clients who have a good understanding of the risks and benefits involved, and are accepting of any potentially negative consequences that may arise.


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