This post comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson.
Fracture fixation with a plate and screws has been around for a century—and so has the problem of screw loosening. Part of the cause of screw loosening seems to be toggling caused by radial forces arising from plate micromotion. Several decades ago, locked screws were designed to prevent loosening and provide better fixation, but screws still loosen.
Two tests can predict screw loosening associated with bone microfracture and absorption: axial pullout stress and toggling radial stress. Recent studies have investigated two hypotheses: radial stress is a predominant cause of screw loosening, and bone resorption is triggered by high radial stress.
Finite Element Analyses
A finite elemental model was used to replicate fixation of a tibial fracture with a 3-mm gap using either a dynamic compression plate (DCP) or locking compression plate (LCP).1 The model included contact with bone, tension on screw insertion, and the placement of two inner screws and one outer screw on either side of the fracture for an 8-hole plate. Axial loading, torsional loading, and bending were applied. Forces exceeding 55 megapascal (MPa) were considered adequate to cause microfracture, whether by radial or axial force. (For reference, 55 MPa is just about 8,000 pounds per square inch.)
The principal finding was that more bone was damaged by radial than by axial stress in both types of plates. Both plate types had more bone damaged by radial stress at the central two screws than at the two end screws for all bending models.
A separate study evaluated clinical radiographs of fixation for humeral, radial, ulnar, femoral, and tibial shaft fractures. Researchers looked for screw migration or bone absorption of ≥1 mm around the screw. Both DCPs and LCPs were reviewed.
Researchers found that the outer screws loosened only after the inner screws loosened. There were 3 cases of bone loss with no loosening, 17 cases of bone loss with screw displacement, and no cases of screw loosening without bone loss. This strongly suggests that bone loss must occur for loosening to take place and that the earliest screw loosening occurs closer to the facture site.
Taken together, these results imply that the use of larger inner screws and/or the use of a different angle of fixation might reduce bone absorption that leads to loosening. In addition, radial stress testing might be more important than axial testing. Still, LCPs remain superior at resisting axial loading and bending moments, while DCPs remain superior at resisting torsional loading of unstable fractures.
- Feng X, Lin G, Fang CX, Lu WW, Chen B, Leung FKL. Bone resorption triggered by high radial stress: The mechanism of screw loosening in plate fixation of long bone fractures. J Orthop Res. 2019 Jul;37(7):1498-1507. doi: 10.1002/jor.24286. Epub 2019 Apr 8 PMID: 30908687
Under one name or another, The Journal of Bone & Joint Surgery has published quality orthopaedic content spanning three centuries. In 1919, our publication was called the Journal of Orthopaedic Surgery, and the first volume of that journal was Volume 1 of what we know today as JBJS.
Thus, the 24 issues we turn out in 2018 will constitute our 100th volume. To help celebrate this milestone, throughout the year we will be spotlighting 100 of the most influential JBJS articles on OrthoBuzz, making the original content openly accessible for a limited time.
Unlike the scientific rigor of Journal content, the selection of this list was not entirely scientific. About half we picked from “JBJS Classics,” which were chosen previously by current and past JBJS Editors-in-Chief and Deputy Editors. We also selected JBJS articles that have been cited more than 1,000 times in other publications, according to Google Scholar search results. Finally, we considered “activity” on the Web of Science and The Journal’s websites.
We hope you enjoy and benefit from reading these groundbreaking articles from JBJS, as we mark our 100th volume. Here are two more:
Autologous Chondrocyte Implantation Compared with Microfracture in the Knee: A Randomized Trial
G Knutsen, L Engebretsen. T C Ludvigsen, J O Drogset, T Grøntvedt, E Solheim, T Strand, S Roberts, V Isaksen, and O Johansen: JBJS, 2004 March; 86 (3): 455
In the first published randomized trial to compare these 2 methods for treating full-thickness cartilage defects, both procedures demonstrated similar clinical results at 2 years of follow-up. The authors also performed arthroscopic and histologic evaluations at 2 years and again found no significant differences between the groups. Since 2004, however, longer-term follow-ups have suggested that autologous chondrocyte implantation is more durable than microfracture (see Clinical Summary on Knee Cartilage Injuries).
The Value of the Tip-Apex Distance in Predicting Failure of Fixation of Peritrochanteric Fractures of the Hip
M R Baumgaertner, S L Curtin, D M Lindskog, and J M Keggi: JBJS, 1995 July; 77 (7): 1058
So-called “cutout” of the lag screw in sliding hip screw fixation of peritrochanteric hip fractures was a recognized cause of failure long before this landmark JBJS study was published in 1995. Twenty-three years later, when value consciousness has repopularized this reliable fixation method (especially in stable fracture patterns), the tip-apex distance as a strong predictor of cutout remains an important surgical consideration.
Every month, JBJS publishes a Specialty Update—a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz Specialty Update summaries.
This month, Chad A. Krueger, MD, JBJS Deputy Editor for Social Media, selected the most clinically compelling findings from among the more than 150 studies cited in the January 17, 2018 Specialty Update on Adult Reconstructive Knee Surgery.
Nonoperative Knee OA Treatment
—Intra-articular corticosteroid injections are commonly administered to mitigate pain and inflammation in knee osteoarthritis (OA). However, a randomized controlled trial of 140 patients found that 2 years of triamcinolone injections, when compared with saline injections, resulted in a significantly greater degree of cartilage loss without significant differences in symptoms.1
Non-Arthroplasty Operative Management
—Knee arthroscopy continues to be largely ineffective for pain relief and functional improvement in knee OA. A randomized controlled trial found no evidence that debridement of unstable chondral flaps found at the time of arthroscopic meniscectomy improves clinical outcomes.
—Cartilage restoration procedures continue to show varying degrees of success. Long-term results from a randomized trial demonstrated no significant differences in joint survivorship and function between patients undergoing microfracture versus autologous chondrocyte implantation (ACI) at 15 years of follow-up. Nearly 50% of patients in both groups had radiographic evidence of early knee OA.
Periprosthetic Joint Infection
—Periprosthetic joint infection (PJI) remains a leading cause of failure following total knee arthroplasty (TKA). Successful treatment requires accurate diagnosis, and alpha-defensin was found to be both sensitive and specific in the diagnosis of PJI. However, it was not significantly superior to leukocyte esterase (LE) in cases of obvious infection.
—Reported rates of reinfection after 2-stage reimplantation for treatment of a first PJI can be as high as 19%. A 3-month course of oral antibiotics following 2-stage procedures significantly improved infection-free survival without complications.2
Post-TKA Complications from Opioids
—Amid ongoing concerns about opioid misuse, two studies3 suggested that preoperative opioid use was found to be an independent predictor of increased length of stay, complications, readmissions, and less pain relief following TKA.
- McAlindon TE, LaValley MP, Harvey WF, Price LL, Driban JB, Zhang M,Ward RJ. Effect of intra-articular triamcinolone vs saline on knee cartilage volume and pain in patients with knee osteoarthritis: a randomized clinical trial. 2017 May 16;317(19):1967-75.
- Frank JM, Kayupov E, Moric M, Segreti J, Hansen E, Hartman C, Okroj K,Belden K, Roslund B, Silibovsky R, Parvizi J, Della Valle CJ; Knee Society Research Group. The Mark Coventry, MD, Award: oral antibiotics reduce reinfection after two-stage exchange: a multicenter, randomized controlled trial. Clin Orthop Relat Res.2017 Jan;475(1):56-61.
- Rozell JC, Courtney PM, Dattilo JR, Wu CH, Lee GC. Preoperative opiate use independently predicts narcotic consumption and complications after total joint arthroplasty. J Arthroplasty.2017 Sep;32(9):2658-62. Epub 2017 Apr 12.
Articular cartilage is a unique and complex tissue. The interactions among chondrocytes, water, and matrix macromolecules provide articular cartilage with its special properties, including the absorption and distribution of compressive loads and low-friction articulation of synovial joints. However, this complex, unique, and sophisticated tissue does not repair itself well and cartilage repair recently has become the target of numerous investigations. Indeed, the natural history of articular cartilage defects is not well defined and thus the development of treatment strategies has been limited. One technique that has gained some success is microfracture.
Microfracture is a commonly employed operative technique that is considered to be safe, relatively inexpensive, and minimally invasive as a first-line treatment for small, contained articular cartilage defects. The scientific basis of microfracture is that disruption of blood vessels in the subchondral bone will cause bleeding in the cartilage defect, leading to the formation of a fibrin clot. It has been suggested that if the clot is protected from loading, undifferentiated mesenchymal stem cells from the bone marrow will migrate into the defect, proliferate, and differentiate into fibrochondrocytes. These chondrocytes then synthesize a fibrocartilaginous matrix that fills the defects. Evidence has shown that microfracture has acceptable short-term clinical results, but those results can be expected to decline over time. What is most important for the surgeon is to determine which patients are the best candidates for this procedure and which patients should not be so treated.
Determining which patients and which cartilage defects are best treated with microfracture can be difficult. Moreover, as the results have been reported over the years, the indications for this technique have narrowed. Clinical experience has shown that lesions measuring >4 cm2 have been associated with worse outcomes. On the other hand, the minimum defect size for which microfracture should be used has not been clearly defined. Another factor is age, with younger patients having better clinical outcomes. Defect location also affects outcomes, with better results having been reported following the treatment of defects involving the femoral condyles. Finally, body mass index (BMI) is a potential risk factor for the failure of this procedure as patients with a BMI of >30 kg/m2 have had significantly lower outcomes scores and subjective ratings compared with those with a BMI below that threshold.
In the June 2016 issue of JBJS Reviews, Sommerfeldt et al. provide a critical overview of microfracture. The authors conclude that microfracture is likely to produce acceptable clinical results in the short term but that the results cannot be guaranteed over the long term. This is an important article for orthopaedic surgeons who perform this technique and for surgeons who seek to understand the basic mechanisms that support this treatment modality.
Thomas A. Einhorn, MD
Editor, JBJS Reviews
Every month, JBJS publishes a Specialty Update—a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Here is a summary of selected findings from Level I and II studies cited in the April 15, 2015 Specialty Update on sports medicine:
–A systematic review of Level-I and II studies suggests that the structural integrity of rotator cuff repairs (or lack thereof) does not correlate with validated patient subjective outcome measures.
–Authors of a randomized clinical trial comparing open and arthroscopic stabilization for recurrent anterior shoulder instability concluded that young male patients with visible Hill-Sachs lesions on radiographs may fare better with open repairs.
–A quantitative literature synthesis of 31 studies (2,813 shoulders) supported primary surgery for highly active young adults who sustain an anterior shoulder dislocation.
–Following rotator cuff surgery, patients randomized to receive a combined axillary and suprascapular nerve block experienced less pain and a lower frequency of rebound pain in the first 36 hours than those receiving only a suprascapular nerve block.
–A Level-II meta-analysis of early passive motion versus strict sling immobilization after arthroscopic rotator cuff repair found that early passive motion resulted in improved forward flexion at 6 and 12 months, with no apparent increased retear rate.
–A randomized trial comparing single- and double-bundle ACL reconstruction with the use of hamstring autograft found no differences in pivot shift or clinical scores at two years.
–Twenty patients with subacute ACL injuries were randomized to “prehabilitation” or control groups. At 12 weeks after surgery, the prehab group showed sustained improvements in single-leg hop and Cincinnati scores, but peak torque and muscle-mass gains had regressed to levels similar to those in the control group.
–A randomized study comparing contralateral versus ipsilateral hamstring tendon harvest for ACL repair identified neither drawbacks nor advantages with the contralateral approach.
–Sixty patients who’d received an isolated meniscal repair were randomized to get either a traditional rehab protocol (brace and toe-touch weigh bearing) or “free rehabilitation.” Based on MRI, partial healing or lack of healing occurred in 28% of the free rehabilitation group and in 36% of the traditional group.
–Authors of a systematic review concluded that nonirradiated allogenic tissue may be superior to radiated allografts for primary ACL reconstruction.
–A randomized controlled trail comparing microfracture alone to microfracture plus application of a novel chitosan-based device demonstrated greater lesion filling and superior repair tissue with the novel device, although there were no differences in clinical benefit and safety at 12 months.
–A randomized controlled trial comparing accelerated with conventional rehabilitation following cartilage repair found that the accelerated group reached full weight-bearing two weeks earlier than the conventional group and reported higher quality-of-life scores.
–In a Level-II study of a population with acute hamstring injuries, those who received a single autologous platelet-rich plasma injection plus rehab had significantly reduced return-to-play time than a group that received rehab without the injection.
–A randomized study of 230 patients with chronic lateral epicondylitis found that those receiving leukocyte-enriched platelet-rich plasma had “clinically meaningful improvement” in pain at 24 weeks, compared to those in an “active control” group.
Foot & Ankle
–A randomized study of 84 patients with nonsurgically treated Achilles tendon tears showed no significant differences in rerupture rates or return-to-work times between a group given a weight-bearing cast and a group given a non-weight-bearing cast.
–A randomized trial of 200 patients with Achilles ruptures compared stable surgical repair and accelerated rehabilitation to nonoperative management. Surgical repair was not found to be superior to nonoperative treatment in terms of functional results, physical activity, or quality of life.