Periprosthetic infections - how do we know when our treatment has been successful?

Definition of Successful Infection Management and Guidelines for Reporting of Outcomes After Surgical Treatment of Periprosthetic Joint Infection

These authors have defined four tiers of outcome after treatment of periprosthetic infections:

Tier 1. Infection control with no continued antibiotic therapy (“infection control” defined as  a patient not having or needing any additional surgery and not meeting the MSIS criteria for a PJI (New Definition for Periprosthetic Joint Infection: From the Workgroup of the Musculoskeletal Infection Society)

Tier 2. Infection control with the patient on suppressive antibiotic therapy

Tier 3. Need for reoperation and/or revision and/or spacer retention (assigned to subgroups A, B, C, D, E, and F basedon the type of reoperation)
   A. Aseptic revision at >1 year from initiation of PJI treatment
   B. Septic revision (including debridement, antibiotics, and implant retention [DAIR]) at >1 year from initiation of PJI treatment (excluding amputation, resection arthroplasty, and arthrodesis)
   C. Aseptic revision at 1 year or less from initiation of PJI treatment
   D. Septic revision (including DAIR) at 1 year or less from initiation of PJI treatment (excluding amputation, resection arthroplasty, and arthrodesis)
   E. Amputation, resection arthroplasty, or arthrodesis
   F. Retained spacer

Tier 4. Death (assigned to subgroups A or B).
   A. Death 1 year or less from initiation of PJI treatment
   B. Death >1 year from initiation of PJI treatment

Comment: These are well thought-out definitions of outcomes after the treatment of periprosthetic infections. The challenge we face as shoulder surgeons is that patients meeting the criteria for Tier 1 "Infection Control" (see above) after treatment of Cutibacterium periprosthetic shoulder infection may have persistent or recurrent pain and stiffness - in these situations one cannot be sure if the symptoms are due to persistence of Cutibacterium in the wound. As stated in the MSIS criteria "PJI may be present if fewer than four of these criteria are met." This is particularly the case for Cutibacterium infections that are known for their "stealth" presentations months or years after a procedure.

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Cost-effectiveness and health-care value analysis - the elephant in the room

Patient-Reported Outcome Measures and Health-Related Quality-of-Life Scores of Patients Undergoing Anatomic Total Shoulder Arthroplasty

These authors evaluated Health-related quality-of-life (HRQoL) scores and patient-reported outcome measures (PROMs) in 93 patients at year after anatomic shoulder arthroplasty for advanced glenohumeral osteoarthritis to establish values of HRQoL scores that can be used for cost effectiveness and value analysis and to assess relationships between HRQoL scores and shoulder and upper-extremity PROMs. 

Preoperative and postoperative functional outcomes were assessed with the Disabilities of the Arm, Shoulder and Hand (DASH) score, the American Shoulder and Elbow Surgeons (ASES) score, the Simple Shoulder Test (SST), and a visual analog scale (VAS) for shoulder pain and function. Health utility was assessed with the EuroQol-5 Dimensions (EQ-5D), Short Form-6 Dimensions (SF-6D), and VAS Quality of Life (VAS QoL). 

There were significant improvements in all PROMs and HRQoL scores (p < 0.001) at 1 year after the surgical procedure. 

Each of the metrics showed a large effect size and standardized response mean

The changes in VAS QoL and EQ-5D were significantly correlated with the changes in most PROMs, but the correlation was only weak to moderate.

The authors concluded that PROMs and HRQoL scores are not interchangeable, and studies of the cost-effectiveness and value of shoulder arthroplasty should incorporate both shoulder and upper-extremity PROMs and HRQoL scores. 

Comment: The value of a treatment is defined as the benefit to the patient divided by the cost of rendering that treatment. This article demonstrates that we have robust tools for evaluating the benefit to the patient of shoulder arthroplasty, both with respect to the improvement in patient self-assessed comfort and function (PROMS) and in the quality of life (HRQoL).

For determining the cost-effectiveness and value of treatment, the challenge is the difficulty in measuring the cost of care, the denominator of the value equation.

One recent study demonstrated the complexity of this assessment: Preparing for the bundled-payment initiative: the cost and clinical outcomes of total shoulder arthroplasty for the surgical treatment of glenohumeral arthritis at an average 4-year follow-up

The pre-hospitalization, hospitalization, and posthospitalization periods accounted for 3.5%, 88.4%, and 8.1% of the 4-year total cost of TSA, respectively. Within the pre-hospitalization period, the shoulder computed tomography scan was the most expensive component of care (37% of pre-hospitalization cost). During the hospitalization period, as well as during the entire 4-year study period, the operating room was the most expensive area (81% of hospitalization cost and 71% of total cost). Within the operating room, the implants were the single most expensive component of care (43% of hospitalization cost and 38% of total cost). The surgeon’s fee was $1,470 and was responsible for 8% of total cost. In the post-hospitalization period, home health care was the most expensive component of care (70% of post-hospitalization cost).

What emerges from that study is that 38% of the total cost is the cost of the implants used.

In a recent article, An analysis of costs associated with shoulder arthroplasty, the authors pointed out that the implant brand was a major factor the the cost of shoulder arthroplasty, however, as they stated "Because actual implant costs were the result of confidential contractual negotiations, actual dollar amounts could not be published nor could the brand names be published adjacent to their relative costs."

The most modifiable variable in the value of shoulder arthroplasty is the cost of the implant, yet because of the confidentiality of contract negotiations, the actual cost data are not available for analysis. We are aware of a major medical center that requires that implant vendors offer implant charges that are at the 25th percentile of the charges across the country. This means that, all other things being equal, the value of shoulder arthroplasty at that medical center would be substantially higher than average because their costs are less.

We conclude that we have a good tool-set for measuring the effectiveness of shoulder arthroplasty, but as a specialty, we do not have a meaningful way of measuring the cost of providing this procedure, especially with respect to implant costs, the elephant in the room.

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We have a new set of shoulder youtubes about the shoulder, check them out at this link.

Be sure to visit "Ream and Run - the state of the art"  regarding this radically conservative approach to shoulder arthritis at this link and this link

Use the "Search" box to the right to find other topics of interest to you.

How you can support progress in shoulder surgery

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Irreparable rotator cuff tears

Surgical Management of Irreparable Rotator Cuff Tears

These authors introduce the term "functionally irreparable rotator cuff tear (FIRCT)" to capture patients who would experience failure of an attempted primary rotator cuff repair because of the extent of cuff muscle and tendon damage and other patient-related factors.

Their "bullet points" are listed below.

*Debridement, biceps tenodesis, and/or partial repair of the torn rotator cuff may reduce pain and improve function for selected patients with a FIRCT.

*Static soft-tissue restraints to abnormal glenohumeral head translation, such as implantation of an absorbable balloon in the subacromial space or superior capsular reconstruction (SCR), appear to reduce pain and improve function, although some have reported a relatively high structural failure rate with SCR. (It is of note that neither the balloon or SCR are included in the authors' recommended  methods (see their figure below)).

*When improvement of strength is the primary goal of treatment, tendon transfers provide a viable treatment alternative; most tendon transfers for management of a FIRCT are currently performed with arthroscopically assisted techniques.

*Transfer of the lower portion of the trapezius has emerged as a successful alternative to transfer of the latissimus dorsi, whereas transfer of the latissimus dorsi to the lesser tuberosity is being explored as an alternative to transfer of the pectoralis major for functionally irreparable subscapularis tears.

Comment: This article provides some thoughts on managing irreparable cuff tears. These authors are particularly experienced in the use of tendon transfers.

We use the guidelines below for discussing rotator cuff tear treatment options with our patients (we are not experienced with the tendon transfers described).

We recognize that the presence of a cuff tear is not in and of itself an indication for surgery in that many cuff tears are either asymptomatic or responsive to non operative management.

Acute traumatic reparable rotator cuff tear

   - consider acute rotator cuff repair (see this link)

Chronic cuff tear without arthritis

   - gentle progressive stretching and strengthening (see this link)

   - if unsatisfactory response to non-operative program:

      - if tear is reparable - consider attempting repair (see this link)

       -if tear is irreparable

          -if patient can actively elevate arm above horizontal, consider smooth and move (see this link)

          -if patient is unable to actively raise arm above horizontal, consider reverse total shoulder (see this link)

Chronic rotator cuff tear with arthritis

   - gentle progressive stretching and strengthening (see this link)

   - if unsatisfactory response to non-operative program:

        -if patient can elevate arm above horizontal and if coracoacromial arch is intact, consider CTA arthroplasty (see this link)

        -if patient is unable to actively raise arm above horizontal, consider reverse total shoulder (see this link)

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We have a new set of shoulder youtubes about the shoulder, check them out at this link.

Be sure to visit "Ream and Run - the state of the art"  regarding this radically conservative approach to shoulder arthritis at this link and this link

Use the "Search" box to the right to find other topics of interest to you.

How you can support progress in shoulder surgery

You may be interested in some of our most visited web pages   arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Glenoid component failure in total shoulder arthroplasty.

Glenoid component failure in total shoulder arthroplasty. JBJS

In 2008 we published this article, the findings of which seem as applicable today as they were 4 years ago. Glenoid component failure remains the most common complication of total shoulder arthroplasty. "Glenoid components fail as a result of their inability to replicate essential properties of the normal glenoid articular surface to achieve durable fixation to the underlying bone, to withstand repeated eccentric loads and glenohumeral translation, and to resist wear and deformation. The possibility of glenoid component failure should be considered whenever a total shoulder arthroplasty has an unsatisfactory result. High-quality radiographs made in the plane of the scapula and in the axillary projection are usually sufficient to evaluate the status of the glenoid component. Failures of prosthetic glenoid arthroplasty can be understood in terms of failure of the component itself, failure of seating, failure of fixation, failure of the glenoid bone, and failure to effectively manage eccentric loading. An understanding of these modes of failure leads to strategies to minimize complications related to prosthetic glenoid arthroplasty."At the time of the writing of this article, however, we did not appreciate the possible role of low grade bacterial infection in glenoid component loosening.

We did note particular problems with metal-backed glenoid components, including  the risk of dissociation of the polyethylene surface from its metal backing and accelerated glenoid polyethylene wear. 

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Results of Cemented Total Shoulder Replacement with a Minimum Follow-up of Ten Years JBJS

Results of Cemented Total Shoulder Replacement with a Minimum Follow-up of Ten Years JBJS

While most journals require a minimum of two years of followup for reconstructive procedures, patients are interested in knowing longer term outcomes as well. This study is a Level IV followup of 39 out of 60 arthroplasties performed between June 1995 and October 2000 at a minimum of 10 years after a 'third generation' Tornier total shoulder arthroplasty with keeled flat-back glenoid components.  Glenoid anatomy was characterized by standardized anteroposterior and axillary radiographs of the shoulders obtained preoperatively and postoperatively. The morphology of the glenoid was recorded according to the classification described by Walch. The glenoid was type A2 in eleven cases, type B1 in sixteen, type B2 in ten, and type C in two. Loosening was defined as a radiolucent line score of over 12 (out of a maximum of 18), tilting over 5 degrees or subsidence. The authors observed that some shoulders showed loosening only on the AP view, some only on the axillary and some on both. Over a third of the glenoid components were radiographically loose at the time of followup. The mean radiolucent line score for the B2 and C glenoids was significantly greater than that for the A2 and B1 glenoids.

Superior migration of the humeral component was observed in over two thirds of the cases. None of the glenoid components required revision and the Constant scores showed significant improvement.

The high radiographic loosening rates observed in this study for keeled components are consistent with two previous long term result reports, here and here.

So again, glenoid component fixation, especially when the glenoid is biconcave or retroverted, remains a challenge. While shoulders with loose glenoids may remain functional, this loosening remains a concern that has not been resolved by later generation prostheses.

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Prognostic Factors and Limitations of Anatomic Shoulder Arthroplasty for the Treatment of Posttraumatic Cephalic Collapse or Necrosis (Type-1 Proximal Humeral Fracture Sequelae) JBJS

Prognostic Factors and Limitations of Anatomic Shoulder Arthroplasty for the Treatment of Posttraumatic Cephalic Collapse or Necrosis (Type-1 Proximal Humeral Fracture Sequelae) JBJS

This is an important paper because it demonstrates the need to stratify the analysis of the results of shoulder arthroplasty. Post-traumatic arthritis is not the same as osteoarthritis! The authors provide a minimum of two years of followup on 55 patients with post-traumatic deformity, 44 of which had total shoulder arthroplasty and the remainder hemiarthroplasty. The worst results were in shoulders with cuff degeneration and those with proximal humeral deformity, especially varus malunion of the humerus as shown below

In such cases a standard stemmed humeral component cannot be properly replaced. While tuberosity osteotomy may be tempting, we agree with the authors that it is not a good idea because of problems with non-union and excessive tension on the repositioned cuff. Such situations can sometimes be addressed with resurfacing prostheses.

Even in these expert hands, the results for shoulders with post-traumatic arthritis are inferior to those for osteoarthritis (thus the case for analyzing these results separately). The authors emphasize the technical difficulty of these cases and the fact that each reconstruction must be highly individualized. Care in preoperative templating, subscapularis management, release of contractures, biceps tenodesis/tenotomy, avoiding greater tuberosity osteotomy, broaching, use of smaller stems, cementing (rather than press-fit fixation),  and  consideration of the status of the glenoid surface are all important elements of the procedure.

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Comparison of Patient-Specific Instruments with Standard Surgical Instruments in Determining Glenoid Component Position: A Randomized Prospective Clinical Trial JBJS

Comparison of Patient-Specific Instruments with Standard Surgical Instruments in Determining Glenoid Component Position: A Randomized Prospective Clinical Trial JBJS

This study compared surgeons' ability to achieve a preoperatively determined glenoid position with either (1) novel three-dimensional computed tomographic scan planning software combined with patient-specific instrumentation* (the glenoid positioning system group), or (2) conventional computed tomographic scan, preoperative planning, and surgical technique, utilizing instruments provided by the implant manufacturer (the standard surgical group).  Postoperatively, a second computed tomographic scan was used to define and compare the actual implant location with the preoperative plan.

The average deviation in version was 6.9° in the standard surgical group and 4.3° in the glenoid positioning system group. The average deviation in inclination was 11.6° in the standard surgical group and 2.9° in the glenoid positioning system group.

Once again we come to the value equation: what was the incremental benefit and what was the incremental cost? With respect to the former (benefit), while the results between the two methods were statistically different, it is difficult to know if these differences are of clinical significance in that clinical outcomes are not available for the two groups. With respect to the latter (cost), the data are not provided. The 'Novel simulator' requires reformatting of CT images to produce new two-dimensional images.

The question is 'did the patients having arthroplasty with the patient-specific instruments achieve better clinical results than those with standard instruments?

Our practice is to use standardized two-dimensional images in the form of plain radiographs, saving the costs (and radiation) of CT scans, the proprietary software, the processing costs, and the production of patient-specific instruments.

*ArthroPlan (invented by one of the authors of this paper)

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Pain and smoking JBJS

Smoking Cessation Related to Improved Patient-Reported Pain Scores Following Spinal Care

This article concerns the results for care (predominantly non-operative) of spinal disorders over 8 months, comparing smokers and non-smokers. At the time of entry to care and at the time of discharge from care, smokers reported more pain than nonsmokers did. Smoking cessation prior to treatment or even acutely during the course of care was related to a greater improvement in reported pain. Patients who continued smoking during treatment had no clinically important improvement in reported pain. In the experience of the authors in the context of care by a surgeon for painful spinal disorders, up to 36% of patients are able to quit smoking with an appropriately structured program and education. This study points to a strong association between improved patient-reported pain and smoking cessation.

There seems to be every reason to expect similar results for our management of shoulder disorders. Bottom line: smoking is associated with persistent pain and smoking behavior is modifiable.

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Computer-Navigated Versus Conventional Total Knee Arthroplasty: A Prospective Randomized Trial JBJS

Computer-Navigated Versus Conventional Total Knee Arthroplasty: A Prospective Randomized Trial JBJS

This is a remarkable study: a single surgeon, prospective randomized trial of conventional versus computer navigated total knee arthroplasty - all 520 patients had one of each - the average followup of over 10 years. The bottom line is that there were no differences in clinical or radiographic outcome between the two approaches. The computer assisted knees had 16% longer OR times and 40% longer tourniquet times.

8 knees with the computer-navigated technique and four knees with the conventional technique were revised as a result of aseptic loosening of the femoral component. Twenty-six knees  had anterior femoral notching in the navigation group and six in the conventional group. Five knees in the navigation group had excessive resection of the tibia. Both infections were in the navigation group.

The only shortcoming is that, aside from the surgical times, we were not provided with the incremental costs of computer navigation. Even without these data, this study did not establish value of computer navigation in knee arthroplasty.

There has been some interest in computer navigation in shoulder arthroplasty with studies showing its value in vitro, however, we suspect that clinical studies are likely to yield the same result as the current study regarding total knee. In some respects, shoulder arthroplasty may be even more challenging: the errors made in the total knee series reported here were attributed to 'registration errors', that is failure to properly align the navigation system - the deep location of the glenohumeral joint may make this even more difficult in the shoulder.

Unless the value of computer navigation can be robustly demonstrated in clinical practice, we must question if this is a way that we wish to spend our precious health care dollars.

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Ultrasound-Guided Interscalene Block Anesthesia for Shoulder Arthroscopy JBJS

Ultrasound-Guided Interscalene Block Anesthesia for Shoulder Arthroscopy JBJS

This paper reviews 1319 patients having outpatient arthroscopic surgery and ultrasound-guided interscalene blocks. In the introduction, the authors emphasize the importance of cost control and suggest that interscalene blocks facilitate outpatient procedures by providing muscle relaxation and lessening the need for high-dose opiates and paralytics. Furthermore they point to the postoperative analgesia, which may reduce the need for pain medication after surgery. They also point to the risks of neuropathy and other potential complications of interscalene blocks. They propose that ultrasound guidance may reduce the risk of brachial plexus block and improve its success rate.

In their study patients received both ultrasound-guided interscalene blocks and laryngeal mask airway general anesthesia –distinguishing it from studies in which brachial plexus blocks are used alone without supplementation.

It is important to note that the authors carefully excluded patients with diabetes, patients having manipulations, and patients having capsular releases from this cohort because they were felt to be at high risk for neurological complications. One might extrapolate that these authors would be similarly reluctant to use these blocks in patients having shoulder arthroplasty for the same reasons. Importantly, the authors also carefully excluded patients with any neurologic issues (cervical radiculopathy, multiple sclerosis etc.), infection, coagulopathy, and chronic obstructive pulmonary disease (because of the temporary phrenic nerve paralysis that often results from a plexus block). Only patients of American Society of Anesthesiologists grade 1 or 2 (ASA 1 or 2) were included. The blocks were performed with attending anesthesiologists with more than 50 ultrasound-guided interscalene blocks under their belt. Bottom line is that this study was conducted to optimize both the patients included and the experience of the anesthesiologists.

Patients were discharged 1.5 hours after the end of the arthroscopy and experienced 14 hours of pain relief. The authors carefully documented the complications, very few of which could be attributed to the plexus block. 38 adverse events were noted; three patients had permanent sequelae (an MI, transverse myelitis, and persistent plexopathy). All other cases plexopathy and neuropathy resolved within four months. All but 2.2% of the patients were satisfied to the point that they would choose this anesthetic approach again.

While the authors conclude “Our study strongly supports the use of interscalene block for operative anesthesia and postoperative analgesia in patients undergoing shoulder arthroscopy.”, enthusiasts would be well advised (1) to recognize that “The levels of training and experience of the anesthesiologist are directly proportional to success and safety of regional anesthesia” and (2) to carefully exclude, as these authors admonish, patients at increased risk for complications.

Bottom line: in the hands of highly experienced anesthesiologists, the combination of ultrasound guided plexus block and general anesthesia is a highly attractive option for healthy patients having outpatient arthroscopy. The caveat is that the high degree of success reported here cannot be used to support the application of this anesthetic approach to less healthy patients having more complex surgical procedures and cannot be generalized to less experienced anesthesiologists as we have previously demonstrated.

As explained in previous posts, we avoid the use of brachial plexus blocks in patients having shoulder arthroplasty; they surely do not meet the criteria listed for inclusion in the study discussed above.

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Long-Term Follow-up of Shoulder Hemiarthroplasty for Glenohumeral Osteoarthritis JBJS

Long-Term Follow-up of Shoulder Hemiarthroplasty for Glenohumeral Osteoarthritis JBJS

This Level IV study reports results at an average of 17 years on 25 of 31 shoulders having hemiarthroplasty for glenohumeral arthritis between June 1990 and December 1994. Eight of these shoulders had revisions (three with concentric glenoid wear and five with eccentric glenoid anatomy). Patients having revision were younger than those not having revision surgery. Patients with secondary arthritis (post-traumatic arthritis, capsulorrhaphy arthropathy, osteonecrosis and post-septic arthritis) had poorer functional outcomes than those with primary osteoarthritis.

This paper brings up some questions of interest. The center in which this study was generated is one of the major centers performing total shoulder arthroplasty in the world, so what factors led the surgeons to perform hemiarthroplasty on these patients? Since glenohumeral arthritis affects both sides of the joint, under what circumstances is a hemiarthroplasty the preferred treatment? Twenty-one of the thirty patients (70%) were treated for conditions such as post-traumatic arthritis, capsulorrhaphy arthropathy, osteonecrosis and post-septic arthritis – all of which are associated with a poor prognosis; is there evidence that a total shoulder would have been more effective in these shoulders? Did the patients having conversion of the hemiarthroplasty to total shoulder arthroplasty improve afterwards?

We can conclude from this study that the shoulders of younger patients who often have complex forms of arthritis – especially those with distorted glenoid bony anatomy - are likely to have poor results with humeral hemiarthroplasty. In the absence of a comparable group of patients having other forms of management, we cannot conclude on how these difficult shoulders can best be managed. The paper does not address what the authors describe in the Introduction as the 'major controversy surrounding the use of hemiarthroplasty as compared to total shoulder arthroplasty for glenohumeral osteoarthritis' in that it did not report the results for the similar patients with similar diagnoses having total shoulder arthroplasty between 1990 and 1994 at this institution.

Wouldn't it be more interesting if these authors had included of all patients with the different types of secondary arthritis having either hemiarthroplasty or total shoulder arthroplasty between 1990 and 1994 so that the pretreatment characteristics (including glenoid anatomy) and post-treatment results of each could be compared?

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Prognostic Factors for Bacterial Cultures Positive for Propionibacterium acnes and Other Organisms in a Large Series of Revision Shoulder Arthroplasties Performed for Stiffness, Pain, or Loosening JBJS

Prognostic Factors for Bacterial Cultures Positive for Propionibacterium acnes and Other Organisms in a Large Series of Revision Shoulder Arthroplasties Performed for Stiffness, Pain, or Loosening JBJS

This article from our team at the University of Washington points out the very high incidence of positive cultures for Propionibacterium from tissues and explants cultured at the time of surgical revision of failed arthroplasties that have none of the usual clinical manifestations of infection. This finding has been overlooked in many past investigations because (1) cultures were not obtained due to a lack of clinical suspicion of infection, (2) cultures were not observed long enough for Propionibacterium to manifest itself, or (3) positive cultures were dismissed as contaminants.

Our clinical practice has the opportunity to evaluate and manage a large number of failed shoulder arthroplasties from the Western U.S., most of which had problems of stiffness, pain, or component loosening without redness, swelling, drainage, or abnormal lab results (CBC, sed rate, C reactive protein). Five years ago we reported that in these shoulders the positive culture rate was unexpectedly high. As a result, we intensified our efforts to seek Propionibacterium in specimens harvested from each revision arthroplasty we performed.

We found that 103 of 193 revised shoulders had positive cultures, even though they had none of the traditional clinical evidences of infection. 70% of these positive cultures grew Propionibacterium.  The ability to detect this organism increased when more specimens were cultured and when the cultures were observed for longer periods of time. Using univariate and multivariate statistics, we observed that male gender, humeral osteolysis, humeral component loosening, glenoid wear, cloudy joint fluid and the formation of a membrane between the humeral component and the humeral bone each significantly increased the chances of a positive culture for Propionibacterium. These findings are helpful in that steps to eradicate  Propionibacterium from a surgical site, such as prosthesis exchange and immediate implementation of specific antibiotic treatment, need to be determined at the time of revision surgery - before the results of cultures become known.

We invite the interested reader to use the "Topics" function to find previous posts on Propionibacterium.  In case you are wondering why we don't refer to this organism as P. Acnes, the answer may be found here.

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