Jelle P. van der List

Why Do Medial Unicompartmental Knee Arthroplasties Fail Today

BACKGROUND Failure rates are higher in medial unicompartmental knee arthroplasty (UKA) than total knee arthroplasty. To improve these failure rates, it is important to understand why medial UKA fail. Because individual studies lack power to show failure modes, a systematic review was performed to assess medial UKA failure modes. Furthermore, we compared cohort studies with registry-based studies, early with midterm and late failures and fixed-bearing with mobile-bearing implants. METHODS Databases of PubMed, EMBASE, and Cochrane and annual registries were searched for medial UKA failures. Studies were included when they reported >25 failures or when they reported early (<5 years), midterm (5-10 years), or late failures (>10 years). RESULTS Thirty-seven cohort studies (4 level II studies and 33 level III studies) and 2 registry-based studies were included. A total of 3967 overall failures, 388 time-dependent failures, and 1305 implant design failures were identified. Aseptic loosening (36%) and osteoarthritis (OA) progression (20%) were the most common failure modes. Aseptic loosening (26%) was most common early failure mode, whereas OA progression was more commonly seen in midterm and late failures (38% and 40%, respectively). Polyethylene wear (12%) and instability (12%) were more common in fixed-bearing implants, whereas pain (14%) and bearing dislocation (11%) were more common in mobile-bearing implants. CONCLUSION This level III systematic review identified aseptic loosening and OA progression as the major failure modes. Aseptic loosening was the main failure mode in early years and mobile-bearing implants, whereas OA progression caused most failures in late years and fixed-bearing implants.

Primary repair of the anterior cruciate ligament: A paradigm shift

Over the last century, many surgical treatments have been developed in the orthopedic field, including treatments of anterior cruciate ligament (ACL) injuries. These treatments ideally evolve in a process of trial and error with prospective comparison of new treatments to the current treatment standard. However, these evolutions are sometimes not linear and periodically undergo paradigm shifts. In this article, we review the evolution of ACL treatment and explain how it underwent a paradigm shift. Open primary ACL repair was the most common treatment in the 1970s and 1980s, but because multiple studies noted deterioration of outcomes at mid-term follow-up, in addition to several randomized clinical trials (RCTs) that noted better outcomes following ACL reconstruction, the open primary repair technique was abandoned. At the end of the primary repair era, however, several studies showed that outcomes of open primary repair were good to excellent and did not deteriorate when this technique was selectively performed in patients with proximal ACL tears, whereas primary repair led to disappointing and unpredictable results in patients with mid-substance tears. Unfortunately, enrollment of patients in the aforementioned RCTs was already finished, ultimately leading to abandoning of open primary repair, despite the advantages of ligament preservation. In this review, we discuss (I) why the evolution of ACL treatment underwent a paradigm shift, (II) which factors may have played a role in this and (III) what the future role of arthroscopic primary ACL repair is in the evolution of ACL treatments.

The Location of Anterior Cruciate Ligament Tears: A Prevalence Study Using Magnetic Resonance Imaging:

Background: Over the past decade, there has been a resurgence of interest in anterior cruciate ligament (ACL) preservation. Proximal and distal avulsion tears have been treated with arthroscopic primary repair, while augmented repair, remnant tensioning, primary repair with biological scaffold, and remnant preservation have been proposed for different types of midsubstance tears. Currently, the incidence of these different tear types is unknown. Purpose: To propose a magnetic resonance imaging (MRI) classification system for different tear types based on clinical relevance and to assess the distribution of these different ACL tear types. Study Design: Case series; Level of evidence, 4. Methods: A retrospective search in an institutional radiographic database was performed for patients who underwent knee MRI at our institution between June 2014 and June 2016. Patients younger than 18 years and those with reports of chronic tears, partial tears, multiligamentous injuries, were excluded. Tear types were graded as proximal avulsion (distal remnant length >90% of total ligament length, type I), proximal (75%-90%, type II), midsubstance (25%-75%, type III), distal (10%-25%, type IV), and distal avulsion (<10%, type V). An orthopaedic surgeon, a radiologist, and a research fellow graded the tear type on 30 MRIs to determine reliability, and the research fellow graded all MRIs. Inter- and intraobserver reliability were measured using kappa statistics. Results: A total of 353 patients (57% male; mean age, 37.1 years; range, 18.1-81.2 years) were included. Interobserver reliability was 0.670 (95% confidence interval, 0.505-0.836), and intraobserver reliability ranged from 0.741 to 0.934. Incidence of type I tears was 16%, type II tears 27%, type III tears 52%, type IV tears 1%, and type V tears 3% (2.5% with bony avulsion). Type I tears were more common in patients older than 35 years compared with those younger than 35 years (23% vs 8%; P < .001). Conclusion: This classification system was reliable in assessing tear location in acute ACL injuries. Type I tears were seen in 16%, type II in 27%, and type III in 52% of patients in our cohort. These data suggest that there may be greater potential application for ACL preservation techniques.

Medial unicompartmental knee arthroplasty improves congruence and restores joint space width of the lateral compartment

BACKGROUND Osteoarthritic progression of the lateral compartment remains a leading indication for medial unicompartmental knee arthroplasty (UKA) revision. Therefore, the purpose of this study was to evaluate the alterations of the lateral compartment congruence and joint space width (JSW) following medial UKA. METHODS Retrospectively, lateral compartment congruence and JSW were evaluated in 174 knees (74 females, 85 males, mean age 65.5years; SD±10.1) preoperatively and six weeks postoperatively, and compared to 41 healthy knees (26 men, 15 women, mean age 33.7years; SD±6.4). Congruence (CI) was calculated using validated software that evaluates the geometric relationship between surfaces and calculates a congruence index (CI). JSW was measured on three sides (inner, middle, outer) by subdividing the lateral compartment into four quarters. RESULTS The CI of the control group was 0.98 (SD±0.01). The preoperative CI was 0.88 (SD±0.01), which improved significantly to 0.93 (SD±0.03) postoperatively (p<0.001). In 82% of knees, CI improved after surgery, while in 18% it decreased. The preoperative significant JSW differences of the inner (p<0.001) and outer JSW (p<0.001) were absent postoperatively. CONCLUSION Our data suggests that a well-conducted medial UKA not only resurfaces the medial compartment but also improves congruence and restores the JSW of the lateral compartment.

Annual revision rates of partial versus total knee arthroplasty: A comparative meta-analysis

BACKGROUND Utilization of unicompartmental knee arthroplasty (UKA) and patellofemoral arthroplasty (PFA) as alternatives to total knee arthroplasty (TKA) for unicompartmental knee osteoarthritis (OA) has increased. However, no single resource consolidates survivorship data between TKA and partial resurfacing options for each variant of unicompartmental OA. This meta-analysis compared survivorship between TKA and medial UKA (MUKA), lateral UKA (LUKA) and PFA using annual revision rate as a standardized metric. METHODS A systematic literature search was performed for studies quantifying TKA, MUKA, LUKA and/or PFA implant survivorship. Studies were classified by evidence level and assessed for bias using the MINORS and PEDro instruments. Annual revision rates were calculated for each arthroplasty procedure as percentages/observed component-year, based on a Poisson-normal model with random effects using the R-statistical software package. RESULTS One hundred and twenty-four studies (113 cohort and 11 registry-based studies) met inclusion/exclusion criteria, providing data for 374,934 arthroplasties and 14,991 revisions. The overall evidence level was low, with 96.7% of studies classified as level III-IV. Annual revision rates were lowest for TKA (0.49%, CI 0.41 to 0.58), followed by MUKA (1.07%, CI 0.87 to 1.31), LUKA (1.13%, CI 0.69 to 1.83) and PFA (1.75%, CI 1.19 to 2.57). No difference was detected between revision rates for MUKA and LUKA (p=0.222). CONCLUSIONS Revisions of MUKA, LUKA and PFA occur at an annual rate of 2.18, 2.31 and 3.57-fold that of TKA, respectively. These estimates may be used to inform clinical decision-making, guide patient expectations and evaluate the cost-effectiveness of total versus partial knee replacement in the setting of unicompartmental OA.

Gap formation following primary repair of the anterior cruciate ligament: A biomechanical evaluation

BACKGROUND Historically, inconsistent and unpredictable results of open primary anterior cruciate ligament (ACL) repair were reported. Recently, however, good results of arthroscopic primary ACL repair of proximal tears have been reported. Purpose of this study was to assess the direct postoperative gap formation and maximum failure load following simulated knee motion after primary ACL repair. METHODS Six matched-paired human cadaveric knees (mean age: 52years, range: 48 to 56years) were used. After primary proximal ACL repair with either suture button fixation or suture anchor fixation, knees were cycled five, 50 and 100 times with a simulated active quadriceps force. Gap formation between the femoral wall and ligament was measured using a digital caliper and maximum failure load was tested. RESULTS Gap formation after five, 50 and 100cycles of the knee were 0.30mm (±0.23), 0.75mm (±0.55) and 0.97mm (±0.70), respectively, with no significant differences between both fixation techniques. The overall maximum failure load was 243N (±143) with no difference between both techniques. Most common failure mode was slipping of suture from the fixation. CONCLUSION Following proximal ACL repair, gap formation of approximately one millimeter was measured after repetitious knee cycling with mean maximum failure load of 243N. These findings are likely to be sufficient for careful early active range of motion (ROM) when extrapolating from other available studies. Future studies with second-look arthroscopy are necessary to assess the gap formation and healing in patients treated with primary repair.

Range of motion and complications following primary repair versus reconstruction of the anterior cruciate ligament

INTRODUCTION Recently, there has been a resurgence of interest in primary anterior cruciate ligament (ACL) repair. The procedure is less invasive than ACL reconstruction, yet studies assessing early postoperative course are lacking. Goal therefore was to assess postoperative range of motion (ROM), complications and operative times following primary repair and compare this to the gold standard of reconstruction. METHODS A retrospective study was performed for which 52 repair and 90 reconstruction patients could be included. Patients were examined at one week and one, three and six months. Rehabilitation protocol consisted of early ROM and was equal for both groups. Outcomes were compared using independent t-tests and chi-square tests, and reported in mean±standard deviation. RESULTS Repair had more ROM than reconstruction patients at one week (89°±18 vs. 61°±21, p<0.01) and one month (125°±14 vs. 116°±18, p < 0.01) postoperatively. Fewer repair patients had 90° ROM at one week (23% vs. 84%, p<0.01), and more repair patients had full ROM at one month (57% vs. 30%, p<0.01). Treatment of meniscal lesions, but not chondral lesions, influenced ROM. Trends towards fewer complications (2% vs. 9%, p=0.19) and infections (0% vs. 6%, p=0.20) were noted following primary repair, and the procedure was significantly shorter. CONCLUSIONS Following primary repair, patients had better ROM, and trends towards fewer complications than reconstruction. Primary repair is a safe, brief procedure with early ROM and low complication rates.

Role of tear location on outcomes of open primary repair of the anterior cruciate ligament: A systematic review of historical studies

BACKGROUND The general opinion is that outcomes of open primary repair of the anterior cruciate ligament (ACL) in the historical literature were disappointing. Since good outcomes of primary repair of proximal tears have recently been reported, we aimed to assess the role of tear location on open primary repair outcomes in the historical literature. METHODS All studies reporting outcomes of open primary ACL repair published between the inception of PubMed, Embase and Cochrane and 2000 were identified. Studies were included if tear location was reported. Outcome scores, return to sports, stability examinations, failures and patient satisfaction were collected and reviewed in the total study cohort and in a subgroup of studies treating only proximal tears. Spearman correlation analysis was performed between the percentage of proximal tears in the studies and all outcomes. RESULTS Twenty-nine studies were included reporting outcomes of open primary in 1457 patients of which 72% had proximal and 23% midsubstance tears. Mean age was 30years, 65% were males, and mean follow-up was 3.6years. Good outcomes were noted in the total cohort, and excellent outcomes were noted following repair of proximal tears. Positive correlation was found between the percentage proximal tears in the studies and percentage satisfied patients (p=0.010). CONCLUSION Tear location seems to have played a role on the outcomes of open primary ACL repair. Outcomes of open primary repair in patients with proximal tears were excellent, which confirms there may be a potential role for primary repair as treatment for proximal ACL tears.

Outcomes of cementless unicompartmental and total knee arthroplasty: A systematic review

BACKGROUND Aseptic loosening is a common failure mode in cemented unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). This led to the development of cementless designs but the historical outcomes were poor. Recent developments in cementless designs have improved outcomes, but the current status is unknown. Therefore, a systematic review was performed to assess recent outcomes of cementless knee arthroplasty. METHODS A search was performed using PubMed, Embase and Cochrane systems and national registries for studies reporting outcomes since 2005. Fifty-two cohort studies and four registries reported survivorship, failure modes or functional outcomes of cementless UKA and TKA. RESULTS Nine level I studies, six level II studies, three level III studies, 34 level IV studies and four registries were included. Three hundred eighteen failures in 10,309 cementless TKA procedures and 62 failures in 2218 cementless UKA procedures resulted in extrapolated five-year, 10-year and 15-year survivorship of cementless TKAs of 97.7%, 95.4% and 93.0%, respectively, and cementless UKA of 96.4%, 92.9% and 89.3%, respectively. Aseptic loosening was more common in cementless TKA (25%) when compared to UKA (13%). Functional outcomes of cementless TKA and UKA were excellent with 84.3% and 84.5% of the maximum possible scores, respectively. CONCLUSIONS This systematic review showed that good to excellent extrapolated survivorship and functional outcomes are seen following modern cementless UKA and TKA, with a low incidence of aseptic loosening following cementless UKA. LEVEL OF EVIDENCE Level IV.

Different optimal alignment but equivalent functional outcomes in medial and lateral unicompartmental knee arthroplasty

INTRODUCTION Several differences in kinematics, functional outcomes and alignment exist between medial and lateral unicompartmental knee arthroplasty (UKA). Therefore, the purpose of this study was (1) to compare functional outcomes between both procedures with the hypothesis that both have equivalent outcomes and (2) to assess the role of preoperative and postoperative alignment on functional outcomes in both procedures. METHODS Patients who underwent UKA were included when overall function - using Western Ontario and McMaster Universities Arthritis (WOMAC) score - and joint awareness - using Forgotten Joint Score (FJS) - were available preoperatively and at minimum two-year follow-up. A total of 143 medial UKA and 36 lateral UKA patients reported outcomes at mean 2.4-years follow-up (range 2.0 to 5.0year). RESULTS Preoperatively and postoperatively, no differences were seen between medial and lateral UKA in overall function (89.8±11.7 vs. 90.2±12.4, respectively, p=0.855) and joint awareness (71.2±24.5 vs. 70.9±28.2, respectively, p=0.956). With neutral postoperative alignment (-1° to three degrees), less joint awareness was noted following medial UKA than lateral UKA (72.6±22.6 vs. 55.3±28.5, p=0.024). With undercorrection (three degrees to seven degrees), however, following lateral UKA less joint awareness (85.3±19.5 vs. 68.2±26.8, p=0.020) and better functional outcomes (96.0±5.4 vs. 88.5±11.6, p=0.001) were noted than medial UKA. CONCLUSION Equivalent functional outcomes were noted between medial and lateral UKA at short-term follow-up but different optimal alignment angles seem to exist for both procedures. LEVEL OF EVIDENCE Level III therapeutic study.